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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/12490-0.txt b/12490-0.txt new file mode 100644 index 0000000..3c79bea --- /dev/null +++ b/12490-0.txt @@ -0,0 +1,3981 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 12490 *** + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 492 + + + + +NEW YORK, JUNE 6, 1885. + +Scientific American Supplement. Vol. XIX, No. 492. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + + * * * * * + + +TABLE OF CONTENTS. + +I. ENGINEERING AND MECHANICS.--The New Spanish Artillery.--2 + engravings. + + Qualitative Tests for Steel Rails.--By L. TETMAJER. + + A New Form of Small Bessemer Plant.--By A. TRAPPEN. + + Triple Compound Engines.--A paper read by A.E. SEATON + before the Institution of Naval Architects. + + Early History of the Steam Jack. + + Bridge over the River Adige, at Verona.--13 figures. + + Pumping Machinery.--Mine pumps.--Direct acting steam pumps. + By E.D. LEAVITT. + + Improved Gun Pressure Gauge.--2 figures. + + Measuring the Thickness of Boiler Plates. + + On an Express Engine. + + +II. TECHNOLOGY.--Improved Plaiting Machine.--With engraving. + + Self-acting Shuttle Guard.--1 figure. + + Ruler and Triangle for Hatching. + + The Distillation of Sea Water.--1 figure. + + Aids to Correct Exposure on Photographic Plates.--An + interesting paper by W. GOODMAN. + + Isochromatic Photography.--By FRED. E. IVES.--2 figures. + + Distortion from Expansion of the Paper in Photography. + + +III. ELECTRICITY, ETC.--On the Fritts Selenium Cells and + Batteries.--A paper read before the American Association + by C.E. FRITTS. + + Electricity Applied to the Manufacture of Varnish.--2 figures. + + Naglo Brothers' Telephone System.--3 figures. + + The Gerard Electric Lamp.--1 figure. + + A New Reflecting Galvanometer.--3 figures. + + +IV. ART AND ARCHITECTURE.--Groups of Statuary for the Pediment + of the House of Parliament in Vienna.--2 engravings. + + The Casino at Monte Carlo.--An engraving. + + +V. PHYSICS.--Determining the Density of the Earth.--1 figure. + + Physics without Apparatus.--The Porosity and Permeability of + Bodies.--A Hot Air Balloon.--2 engravings. + + +VI. NATURAL HISTORY.--Winter and the Insects.--An engraving. + + Silk Worm Eggs.--With engraving. + + +VII. HORTICULTURE.--The Melleco.--Ullucus tuberosa.--With + engraving. + + +VIII. PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section + cutting machines.--Methods of preserving the + tissues.--Preservative media.--Preparation for mounting + tissues.--1 figure. + + Life History of a New Septic Organism. + + Erythroxylon Coca as a Therapeutic Agent.--By Dr. E.R. SQUIBB. + + * * * * * + + + + +NEW SPANISH ARTILLERY. + + +The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +We give engravings from photographs, as presented in _La Illustracion +Española_. These guns are breech loaders, of steel, 30½ centimeters +caliber, or 12 inches, 49 tons weight. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness. + + * * * * * + + + + +QUALITATIVE TESTS FOR STEEL RAILS. + +By Mr. L. TETMAJER. + + +This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice. + +The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same. + +The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensücherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.--_Stahl und Eisen_, vol. iv., page 608; through +_Proc. Inst. Civ. Eng_. + + * * * * * + + + + +A NEW FORM OF SMALL BESSEMER PLANT. + +By Mr. A. TRAPPEN. + + +The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift. + +The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure. + +The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at £2,050 +to £2,100; and that of the steam boiler, £325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.--_Stahl und +Eisen_, vol. iv., page 524; through _Proc. Inst. Civ. Eng_. + + * * * * * + + + + +TRIPLE COMPOUND ENGINES. + +[Footnote: Paper read before the Institution of Naval Architects, March +27, 1885.] + +By Mr. A.E. SEATON. + + +My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small. + +The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows: + + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 + +And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment. + +After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent. + +In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day. + +The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure. + +So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 20½ inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear. + +I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +½ knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other. + +We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 11½ inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen. + +I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands. + + * * * * * + + + + +EARLY HISTORY OF THE STEAM JACK. + +_To the Editor of the Scientific American:_ + + +A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack." + +Says Mr. J.G. Briggs, in the _American Engineer:_ "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.--a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country--if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment _patent_, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the _Hub_, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston. + +Trusting I have not wearied you, I am, + +ANNA M. BAILEY. + +Bleak House, Lynn, Mass., May 12. + + +COPY OF PATENT. + +_United States_. + +To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. Go. WASHINGTON. + +By the President, + +TH. JEFFERSON. + + +CITY OF PHILADELPHIA, February 23, 1792. + +I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act. + +EDM. RANDOLPH, + +_Attorney-General of the U.S._ + +[SEAL.] + + * * * * * + + + + +BRIDGE AT VERONA. + + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge: + + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 9¾ +Width of bridge 37 4¾ +Depth of arched girders 4 7 + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 _l._; the abutments cost 3,600_l._, +making the total outlay on the structure 12,000_l_. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.--_Engineering_. + + * * * * * + + + + +PUMPING MACHINERY. + +[Footnote: A paper read at the Montreal Meeting of the British +Association.] + +By E.D. LEAVITT, JR., Cambridgeport, Mass. + +MINE PUMPING MACHINERY. + + +One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine. + +At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia Water Works; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines. + +In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well. + +The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States. + +A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned. + +Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet. + +The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps. + +The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 22½ feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine. + +In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 4½ inches thickness of metal. The pump rock shaft +is 39 feet 4½ inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine. + +The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft. + +The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to ½ inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute. + +The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 17½ inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same. + +The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections. + +The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links. + +The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 5¼ inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity. + +The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory. + + +DIRECT ACTING STEAM PUMPS. + +This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined. + +The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish. + + * * * * * + + + + +IMPROVED GUN PRESSURE GAUGE. + + +The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor. + +[Illustration: IMPROVED GUN PRESSURE GAUGE.] + +Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb. + +It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with. + +The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds. + +The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice. + +This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder. + + * * * * * + + + + +IMPROVED PLAITING MACHINE. + + +The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length. + +[Illustration: IMPROVED PLAITING MACHINE.] + +To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner: + +Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G¹ G¹. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires. + +It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.--_Tex. Manfr._ + + * * * * * + + + + +SELF-ACTING SHUTTLE GUARD. + + +[Illustration: SELF-ACTING SHUTTLE GUARD.] + +The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers. + + * * * * * + + + + +RULER AND TRIANGLE FOR HATCHING. + + +The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45°, but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former. + +[Illustration: RULER AND TRIANGLE FOR HATCHING.] + +The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.--_Chronique Industrielle_. + + * * * * * + + + + +THE DISTILLATION OF SEA WATER. + + +The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service. + +Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process. + +In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried. + +Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 4½ cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes--in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser. + +[Illustration] + +Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order. + +As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +2¼ gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance. + +Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is _said_ are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.--_The Engineer_. + + * * * * * + + + + +AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES. + +[Footnote: We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.] + + +With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative. + + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ + +The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum. + +The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done. + +Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed. + +The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both. + +The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens. + +The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size. + +First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch. + +Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 7½ in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two. + +We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table. + +We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium _nitrite_ (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough. + +However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass. + +Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done--kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer. + +When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right. + +Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table. + +You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only. + +On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures. + +I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous. + +The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you _may_ make a negative of an overexposed plate, but never +of an underexposed one. + + * * * * * + + + + +ISOCHROMATIC PHOTOGRAPHY. + +[Footnote: Read at the stated meeting of the Franklin Institute, March +18, 1885.] + +By FRED. E. IVES. + + +It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography. + +Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process. + +In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, _why_ it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives--blue, yellow, and red--would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow. + +Having succeeded perfectly in my undertakings, I published my discovery +in 1879,[1] explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.[2] + +[Footnote 1: _Philadelphia Photographer_, December, 1879, p. 365.] + +[Footnote 2: I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the _Photo. News_, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +_Photo. News_, Nov. 1883, p. 747.] + +So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,[3] +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness. + +[Footnote 3: _Photo. News_, London, September 5, 1884, p. 566, and _Year +Book of Photography_ for 1885, p. 111.] + +My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.[4] A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure. + +[Footnote 4: I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from _fresh_ +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.] + +My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement. + +The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer. + +[Illustration: IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.] + +In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank. + +I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them. + +To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered. + +Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness. + +I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination. + +Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but _comparatively insensitive to +red_, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process. + + * * * * * + + + + +DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY. + + +The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper. + +When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears. + +If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness--owing to +this particular distortion--of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied. + +Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby. + +To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight--perhaps imperceptible--compared with that existing +when the prints are mounted wet. I may mention, _en passant_, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system. + +The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion. + +For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there. + +Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion. + +A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass. + +Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled. + +The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.--_W.E. +Debenham, in Br. Jour. of Photography_. + + * * * * * + + + + +MEASURING THE THICKNESS OF BOILER PLATES. + + +An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy. + + * * * * * + + + + +GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA. + + +The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--SCIENCE +AND LITERATURE. (GROUP TO THE LEFT.)] + +The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government. + +Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows. + +A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry. + +Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--INDUSTRY +AND COMMERCE. (GROUP TO THE RIGHT.)] + +The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.--_Illustrirte Zeitung_. + + * * * * * + + + + +ON THE FRITTS SELENIUM CELLS AND BATTERIES. + +[Footnote: Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.] + +By C.E. FRITTS, 42 Nassau St., New York, N.Y. + + +In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface. + +My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure. + +During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a _transparent conductor of electricity_, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.[5] My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired. + +[Footnote 5: The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.] + +By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following: + +1. _Their sensitiveness to light_ is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells. + +It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 _per cent_. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained _less than 3/10 of 1 per cent_. of the original +resistance of the selenium in dark. + +In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act +through the gold, in conjunction, their forces are united; and, as every +atom of the selenium is affected by the light, owing to the extreme +thinness of the plate, we have the full effect shown in the measurements. + + TABLE A. + + SENSITIVENESS TO LIGHT. + +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23[6]|5 " | 14,000 | 170 | 82.3 " " + " 24[7]|5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129[6]|5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- + +[Footnote 6: Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.] + +[Footnote 7: No. 24 was measured with a bridge multiplier of 6 to 1.] + +Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not. + +_Mode of measuring cells_.--So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently. + +The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison. + +2. _The kind of battery employed_ has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the _resistance_ +of a cell, but it is not clear how or why it should affect the +_sensitiveness of selenium to light_. + +"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?" + +One year ago I made the foregoing suggestion in a paper on _A New Form of +Selenium Cell_, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells. + +3. _The two surfaces of the selenium act differently toward currents_ +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results. + + TABLE B. + + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. + +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- + +The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark. + +4. _Sensitiveness to change of battery power_.--My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified-- + +(a) By changing the potential or electromotive force of the current +through the cell. + +(b) By changing the "quantity" of the battery or current. + +(c) By putting more or less resistance in the circuit. + +(d) By dividing the current, by one or more branch circuits or shunts +around the cell. + +(e) By varying the resistance in any or all of said circuits. + +A cell whose resistance becomes greater as the battery power becomes +greater, and _vice versa_, I call an "L B cell" signifying _Like the +Battery power_. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and _vice +versa_, being _Unlike the Battery power_, or current strength. + +These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change. + +The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms. + + TABLE C. + + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123[8] | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- + +[Footnote 8: This measurement was obtained with 8 elements.] + +The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark. + +5. _Dual state of selenium_.--My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable. + +In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another. + +The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed? + +6. _Radio-electric current generators_.--My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means. + +The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted. + +I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required. + +7. _Singing and speaking cells_.--When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current--and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit. + +My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation. + +GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS. + +From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells." + +The property of sensitiveness to light is independent of the power to +generate current by exposure to light--the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat. + +The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light--their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them. + +The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light. + +_Constancy of the resistance_.--A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms--sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant. + +As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness. + +_Practical applications_.--There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale. + +The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my + +_Photometer_.--The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights--the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light. + +This arrangement leaves untouched the old difficulty in photometry, that +arising from the different _colors_ of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration. + +_Photo-electric regulator_.--My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small. + +In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries. + + * * * * * + + + + +ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH. + + +Messrs. Müthel & Lütche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on. + +The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures. + +The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever. + +[Illustration: FIGS. 1 AND 2.] + +The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60° and 80°. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone. + +When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.--_La Lumiere +Electrique._ + + * * * * * + + + + +NAGLO BROTHERS' TELEPHONE SYSTEM. + + +We borrow from the _Elektrotechnische Zeitung_ the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f_{2}. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f_{1}. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle. + +[Illustration: FIG. 1.] + +Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve. + +This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f_{2} p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling. + +[Illustration: FIGS. 2 AND 3.] + +Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.--_La Lumiere Electrique_. + + * * * * * + + + + +THE GERARD ELECTRIC LAMP. + + +In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage. + +This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp: + + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 + +[Illustration: GERARD'S INCANDESCENT LAMP.] + +It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example--this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps. + +The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature. + +The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.--_Le Genie +Civil_. + + * * * * * + + + + +A NEW REFLECTING GALVANOMETER. + + +Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106° with each other, so that the planes containing the axes of the +bobbins make an angle of about 74°. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated. + +[Illustration: FIG. 1. GRAY'S GALVANOMETER.] + +The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections. + +In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite. + +[Illustration: FIG. 2.] + +The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread. + +The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T¹, T², and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite. + +Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation. + +In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10^{4} to 10^{5} megohms could be +measured by the use of a pile of 120 daniells. + +The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier. + +The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one. + +We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane. + +Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.--_La Lumiere Electrique_. + + * * * * * + + + + +HISTOLOGICAL METHODS. + + +A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required. + +Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly. + +Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol. + +The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol. + +_Section cutting_ machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument. + +A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal. + +When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed. + +With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose. + +[Illustration: FIG. 1.] + +_To out a section by hand_, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush. + +When the object is too small to hold, it is usually _embedded_ in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it. + +Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive. + +Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues. + +Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes. + +Much practice will be required before dexterity is attained. + +_Methods of preserving the tissues_.--All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote. + +The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium. + +The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off. + +_Preservative media_.--Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150°; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine. + +Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased. + +Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained. + +Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts. + +When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement. + +_Preparation for mounting the different tissues_.--To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine. + +Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting. + +The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach. + +The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly. + +The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution. + +Every slide should be of uniform size, and labeled. The usual size is 3×1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required. + + * * * * * + + + + +LIFE HISTORY OF A NEW SEPTIC ORGANISM. + + +At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice +versa_, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form--extending over four years--he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of _Bacterium termo_, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms--one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90° to 95° F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements. + +The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146° F., the highest point endured +by the germs was 190° F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the _modus operandi_ was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law. + + * * * * * + + + + +WINTER AND THE INSECTS. + + +For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellae, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick. + +[Illustration: GREEN WOODPECKER SEARCHING FOR INSECTS.] + +The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line--this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil. + +I now come to the effects of this severe cold upon the insects. + +The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellae, in view of the +previous rarity of the individuals belonging to this family. + +We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvae, pass this season upon the earth +enveloped in a silken envelope, or, like the larvae of the Noctuellae, +between dead leaves or upon the ground itself. + +On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvae and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvae of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera. + +It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvae. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulae are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvae and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans--the wood lice. + +During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvae and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvae are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared. + +In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvae feed and hibernate in the open air a few species of +Noctuellae, whose larvae live buried in the earth, are always abundant. The +country is relatively rich in spices of _Tortrix_, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.--_C.G. Barret, in Science et Nature_. + + * * * * * + + + + +SILK WORM EGGS. + + +Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called _flacherie_, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs: + +[Illustration] + +For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennae, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths. + +There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3×6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room. + +The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day. + +When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered. + + * * * * * + + +Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine. + + * * * * * + +[NATURE.] + + + + +DETERMINING THE MEAN DENSITY OF THE EARTH. + + +In _Nature_ for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the _Nature_ (Jan. 15. p. 260) report of the +_Proceedings_ of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method. + +Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings. + +A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G. + +[Illustration] + +In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance. + +The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary. + +ARTHUR KONIG. + +FRANZ RICHARZ. + +Berlin, Physical Institute of the University, March 15. + + * * * * * + + + + +PHYSICS WITHOUT APPARATUS. + + +_The Porosity and Permeability of Bodies._--Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are _impermeable_, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so _penetrating_. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action. + +[Illustration: Fig. 1.--EXPERIMENT UPON THE PERMEABILITY OF BODIES.] + +_A Hot Air Balloon_.--Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.--_La Nature_. + +[Illustration: Fig. 2.--PRINCIPLE OF THE HOT AIR BALLOON.] + + * * * * * + + + + +THE CASINO AT MONTE CARLO. + + +The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea. + +[Illustration: THE CASINO AT MONTE CARLO.] + +Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces. + +But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player. + +It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined. + + * * * * * + + + + +ON AN EXPRESS ENGINE. + + +It is a somewhat unpromising morning--the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance. + +So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead--the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed--it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades--for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart--where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.--_Saturday Review_. + + * * * * * + + +The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process. + + * * * * * + + + + +ERYTHROXYLON. + +[Footnote: From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.] + + +COCA. + +The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics. + +The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied. + +Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago. + +The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in _The Lancet_ of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body." + +Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages. + +There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.[9] + +[Footnote 9: An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.] + +The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle--namely, caffeine--could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons. + +In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by. + +An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence. + +Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him. + +The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect. + +Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 2½ grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning. + +This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken. + +The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 2½ drachms did give a +definite effect, and a subsequent dose of 2½ fluid drachms of a well made +fluid extract of coca gave about the same effect as 2½ grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine. + +Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained. + +The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the _American Journal of +Pharmacy_, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows: + +Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent. + +Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory. + +Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid. + +From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process. + +Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle. + + * * * * * + + + + +THE MELLOCO. + + +ULLUCUS TUBEROSA.--Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were. + +[Illustration: MELLOCO TUBERS.] + +We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the _Gardeners' Chronicle_ for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49°." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50° in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements. + +Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers--such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the _Gardeners' Chronicle_ for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.--_W. Waston, Kew; +The Gardeners' Chronicle_. + + * * * * * + + +A catalogue, containing brief notices of many important scientific papers +heretofore published in the SUPPLEMENT, may be had gratis at this office. + + + * * * * * + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + +PUBLISHED WEEKLY. + +TERMS OF SUBSCRIPTION, $5 A YEAR. + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of THE SUPPLEMENT, from the commencement, January 1, +1876, can be had. Price, 10 cents each. + +All the back volumes of THE SUPPLEMENT can likewise be supplied. Two +volumes are issued yearly. 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By the immense circulation thus given, public attention is +directed to the merits of the new patent, and sales or introduction often +easily effected. + +Any person who has made a new discovery or invention can ascertain, free +of charge, whether a patent can probably be obtained, by writing to MUNN +& Co. + +We also send free our Hand Book about the Patent Laws, Patents, Caveats, +Trade Marks, their costs, and how procured. Address + +MUNN & CO., 361 Broadway, New York. + +Branch Office, cor. F and 7th Sts., Washington, D.C. + + + + + + + +End of the Project Gutenberg EBook of Scientific American Supplement, No. +492, June 6, 1885, by Various + +*** END OF THE PROJECT GUTENBERG EBOOK 12490 *** diff --git a/12490-8.txt b/12490-8.txt new file mode 100644 index 0000000..fe12baa --- /dev/null +++ b/12490-8.txt @@ -0,0 +1,4400 @@ +The Project Gutenberg EBook of Scientific American Supplement, No. 492, +June 6, 1885, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 492, June 6, 1885 + +Author: Various + +Release Date: June 2, 2004 [EBook #12490] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 492 + + + + +NEW YORK, JUNE 6, 1885. + +Scientific American Supplement. Vol. XIX, No. 492. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + + * * * * * + + +TABLE OF CONTENTS. + +I. ENGINEERING AND MECHANICS.--The New Spanish Artillery.--2 + engravings. + + Qualitative Tests for Steel Rails.--By L. TETMAJER. + + A New Form of Small Bessemer Plant.--By A. TRAPPEN. + + Triple Compound Engines.--A paper read by A.E. SEATON + before the Institution of Naval Architects. + + Early History of the Steam Jack. + + Bridge over the River Adige, at Verona.--13 figures. + + Pumping Machinery.--Mine pumps.--Direct acting steam pumps. + By E.D. LEAVITT. + + Improved Gun Pressure Gauge.--2 figures. + + Measuring the Thickness of Boiler Plates. + + On an Express Engine. + + +II. TECHNOLOGY.--Improved Plaiting Machine.--With engraving. + + Self-acting Shuttle Guard.--1 figure. + + Ruler and Triangle for Hatching. + + The Distillation of Sea Water.--1 figure. + + Aids to Correct Exposure on Photographic Plates.--An + interesting paper by W. GOODMAN. + + Isochromatic Photography.--By FRED. E. IVES.--2 figures. + + Distortion from Expansion of the Paper in Photography. + + +III. ELECTRICITY, ETC.--On the Fritts Selenium Cells and + Batteries.--A paper read before the American Association + by C.E. FRITTS. + + Electricity Applied to the Manufacture of Varnish.--2 figures. + + Naglo Brothers' Telephone System.--3 figures. + + The Gerard Electric Lamp.--1 figure. + + A New Reflecting Galvanometer.--3 figures. + + +IV. ART AND ARCHITECTURE.--Groups of Statuary for the Pediment + of the House of Parliament in Vienna.--2 engravings. + + The Casino at Monte Carlo.--An engraving. + + +V. PHYSICS.--Determining the Density of the Earth.--1 figure. + + Physics without Apparatus.--The Porosity and Permeability of + Bodies.--A Hot Air Balloon.--2 engravings. + + +VI. NATURAL HISTORY.--Winter and the Insects.--An engraving. + + Silk Worm Eggs.--With engraving. + + +VII. HORTICULTURE.--The Melleco.--Ullucus tuberosa.--With + engraving. + + +VIII. PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section + cutting machines.--Methods of preserving the + tissues.--Preservative media.--Preparation for mounting + tissues.--1 figure. + + Life History of a New Septic Organism. + + Erythroxylon Coca as a Therapeutic Agent.--By Dr. E.R. SQUIBB. + + * * * * * + + + + +NEW SPANISH ARTILLERY. + + +The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +We give engravings from photographs, as presented in _La Illustracion +Española_. These guns are breech loaders, of steel, 30½ centimeters +caliber, or 12 inches, 49 tons weight. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness. + + * * * * * + + + + +QUALITATIVE TESTS FOR STEEL RAILS. + +By Mr. L. TETMAJER. + + +This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice. + +The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same. + +The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensücherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.--_Stahl und Eisen_, vol. iv., page 608; through +_Proc. Inst. Civ. Eng_. + + * * * * * + + + + +A NEW FORM OF SMALL BESSEMER PLANT. + +By Mr. A. TRAPPEN. + + +The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift. + +The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure. + +The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at £2,050 +to £2,100; and that of the steam boiler, £325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.--_Stahl und +Eisen_, vol. iv., page 524; through _Proc. Inst. Civ. Eng_. + + * * * * * + + + + +TRIPLE COMPOUND ENGINES. + +[Footnote: Paper read before the Institution of Naval Architects, March +27, 1885.] + +By Mr. A.E. SEATON. + + +My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small. + +The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows: + + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 + +And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment. + +After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent. + +In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day. + +The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure. + +So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 20½ inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear. + +I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +½ knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other. + +We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 11½ inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen. + +I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands. + + * * * * * + + + + +EARLY HISTORY OF THE STEAM JACK. + +_To the Editor of the Scientific American:_ + + +A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack." + +Says Mr. J.G. Briggs, in the _American Engineer:_ "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.--a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country--if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment _patent_, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the _Hub_, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston. + +Trusting I have not wearied you, I am, + +ANNA M. BAILEY. + +Bleak House, Lynn, Mass., May 12. + + +COPY OF PATENT. + +_United States_. + +To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. Go. WASHINGTON. + +By the President, + +TH. JEFFERSON. + + +CITY OF PHILADELPHIA, February 23, 1792. + +I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act. + +EDM. RANDOLPH, + +_Attorney-General of the U.S._ + +[SEAL.] + + * * * * * + + + + +BRIDGE AT VERONA. + + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge: + + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 9¾ +Width of bridge 37 4¾ +Depth of arched girders 4 7 + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 _l._; the abutments cost 3,600_l._, +making the total outlay on the structure 12,000_l_. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.--_Engineering_. + + * * * * * + + + + +PUMPING MACHINERY. + +[Footnote: A paper read at the Montreal Meeting of the British +Association.] + +By E.D. LEAVITT, JR., Cambridgeport, Mass. + +MINE PUMPING MACHINERY. + + +One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine. + +At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia Water Works; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines. + +In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well. + +The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States. + +A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned. + +Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet. + +The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps. + +The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 22½ feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine. + +In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 4½ inches thickness of metal. The pump rock shaft +is 39 feet 4½ inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine. + +The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft. + +The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to ½ inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute. + +The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 17½ inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same. + +The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections. + +The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links. + +The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 5¼ inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity. + +The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory. + + +DIRECT ACTING STEAM PUMPS. + +This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined. + +The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish. + + * * * * * + + + + +IMPROVED GUN PRESSURE GAUGE. + + +The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor. + +[Illustration: IMPROVED GUN PRESSURE GAUGE.] + +Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb. + +It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with. + +The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds. + +The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice. + +This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder. + + * * * * * + + + + +IMPROVED PLAITING MACHINE. + + +The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length. + +[Illustration: IMPROVED PLAITING MACHINE.] + +To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner: + +Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G¹ G¹. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires. + +It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.--_Tex. Manfr._ + + * * * * * + + + + +SELF-ACTING SHUTTLE GUARD. + + +[Illustration: SELF-ACTING SHUTTLE GUARD.] + +The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers. + + * * * * * + + + + +RULER AND TRIANGLE FOR HATCHING. + + +The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45°, but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former. + +[Illustration: RULER AND TRIANGLE FOR HATCHING.] + +The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.--_Chronique Industrielle_. + + * * * * * + + + + +THE DISTILLATION OF SEA WATER. + + +The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service. + +Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process. + +In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried. + +Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 4½ cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes--in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser. + +[Illustration] + +Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order. + +As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +2¼ gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance. + +Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is _said_ are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.--_The Engineer_. + + * * * * * + + + + +AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES. + +[Footnote: We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.] + + +With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative. + + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ + +The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum. + +The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done. + +Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed. + +The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both. + +The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens. + +The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size. + +First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch. + +Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 7½ in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two. + +We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table. + +We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium _nitrite_ (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough. + +However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass. + +Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done--kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer. + +When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right. + +Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table. + +You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only. + +On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures. + +I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous. + +The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you _may_ make a negative of an overexposed plate, but never +of an underexposed one. + + * * * * * + + + + +ISOCHROMATIC PHOTOGRAPHY. + +[Footnote: Read at the stated meeting of the Franklin Institute, March +18, 1885.] + +By FRED. E. IVES. + + +It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography. + +Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process. + +In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, _why_ it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives--blue, yellow, and red--would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow. + +Having succeeded perfectly in my undertakings, I published my discovery +in 1879,[1] explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.[2] + +[Footnote 1: _Philadelphia Photographer_, December, 1879, p. 365.] + +[Footnote 2: I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the _Photo. News_, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +_Photo. News_, Nov. 1883, p. 747.] + +So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,[3] +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness. + +[Footnote 3: _Photo. News_, London, September 5, 1884, p. 566, and _Year +Book of Photography_ for 1885, p. 111.] + +My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.[4] A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure. + +[Footnote 4: I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from _fresh_ +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.] + +My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement. + +The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer. + +[Illustration: IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.] + +In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank. + +I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them. + +To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered. + +Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness. + +I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination. + +Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but _comparatively insensitive to +red_, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process. + + * * * * * + + + + +DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY. + + +The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper. + +When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears. + +If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness--owing to +this particular distortion--of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied. + +Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby. + +To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight--perhaps imperceptible--compared with that existing +when the prints are mounted wet. I may mention, _en passant_, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system. + +The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion. + +For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there. + +Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion. + +A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass. + +Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled. + +The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.--_W.E. +Debenham, in Br. Jour. of Photography_. + + * * * * * + + + + +MEASURING THE THICKNESS OF BOILER PLATES. + + +An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy. + + * * * * * + + + + +GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA. + + +The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--SCIENCE +AND LITERATURE. (GROUP TO THE LEFT.)] + +The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government. + +Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows. + +A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry. + +Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--INDUSTRY +AND COMMERCE. (GROUP TO THE RIGHT.)] + +The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.--_Illustrirte Zeitung_. + + * * * * * + + + + +ON THE FRITTS SELENIUM CELLS AND BATTERIES. + +[Footnote: Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.] + +By C.E. FRITTS, 42 Nassau St., New York, N.Y. + + +In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface. + +My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure. + +During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a _transparent conductor of electricity_, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.[5] My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired. + +[Footnote 5: The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.] + +By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following: + +1. _Their sensitiveness to light_ is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells. + +It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 _per cent_. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained _less than 3/10 of 1 per cent_. of the original +resistance of the selenium in dark. + +In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act +through the gold, in conjunction, their forces are united; and, as every +atom of the selenium is affected by the light, owing to the extreme +thinness of the plate, we have the full effect shown in the measurements. + + TABLE A. + + SENSITIVENESS TO LIGHT. + +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23[6]|5 " | 14,000 | 170 | 82.3 " " + " 24[7]|5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129[6]|5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- + +[Footnote 6: Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.] + +[Footnote 7: No. 24 was measured with a bridge multiplier of 6 to 1.] + +Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not. + +_Mode of measuring cells_.--So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently. + +The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison. + +2. _The kind of battery employed_ has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the _resistance_ +of a cell, but it is not clear how or why it should affect the +_sensitiveness of selenium to light_. + +"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?" + +One year ago I made the foregoing suggestion in a paper on _A New Form of +Selenium Cell_, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells. + +3. _The two surfaces of the selenium act differently toward currents_ +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results. + + TABLE B. + + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. + +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- + +The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark. + +4. _Sensitiveness to change of battery power_.--My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified-- + +(a) By changing the potential or electromotive force of the current +through the cell. + +(b) By changing the "quantity" of the battery or current. + +(c) By putting more or less resistance in the circuit. + +(d) By dividing the current, by one or more branch circuits or shunts +around the cell. + +(e) By varying the resistance in any or all of said circuits. + +A cell whose resistance becomes greater as the battery power becomes +greater, and _vice versa_, I call an "L B cell" signifying _Like the +Battery power_. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and _vice +versa_, being _Unlike the Battery power_, or current strength. + +These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change. + +The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms. + + TABLE C. + + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123[8] | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- + +[Footnote 8: This measurement was obtained with 8 elements.] + +The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark. + +5. _Dual state of selenium_.--My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable. + +In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another. + +The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed? + +6. _Radio-electric current generators_.--My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means. + +The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted. + +I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required. + +7. _Singing and speaking cells_.--When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current--and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit. + +My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation. + +GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS. + +From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells." + +The property of sensitiveness to light is independent of the power to +generate current by exposure to light--the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat. + +The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light--their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them. + +The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light. + +_Constancy of the resistance_.--A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms--sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant. + +As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness. + +_Practical applications_.--There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale. + +The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my + +_Photometer_.--The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights--the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light. + +This arrangement leaves untouched the old difficulty in photometry, that +arising from the different _colors_ of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration. + +_Photo-electric regulator_.--My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small. + +In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries. + + * * * * * + + + + +ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH. + + +Messrs. Müthel & Lütche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on. + +The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures. + +The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever. + +[Illustration: FIGS. 1 AND 2.] + +The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60° and 80°. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone. + +When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.--_La Lumiere +Electrique._ + + * * * * * + + + + +NAGLO BROTHERS' TELEPHONE SYSTEM. + + +We borrow from the _Elektrotechnische Zeitung_ the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f_{2}. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f_{1}. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle. + +[Illustration: FIG. 1.] + +Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve. + +This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f_{2} p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling. + +[Illustration: FIGS. 2 AND 3.] + +Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.--_La Lumiere Electrique_. + + * * * * * + + + + +THE GERARD ELECTRIC LAMP. + + +In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage. + +This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp: + + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 + +[Illustration: GERARD'S INCANDESCENT LAMP.] + +It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example--this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps. + +The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature. + +The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.--_Le Genie +Civil_. + + * * * * * + + + + +A NEW REFLECTING GALVANOMETER. + + +Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106° with each other, so that the planes containing the axes of the +bobbins make an angle of about 74°. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated. + +[Illustration: FIG. 1. GRAY'S GALVANOMETER.] + +The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections. + +In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite. + +[Illustration: FIG. 2.] + +The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread. + +The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T¹, T², and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite. + +Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation. + +In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10^{4} to 10^{5} megohms could be +measured by the use of a pile of 120 daniells. + +The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier. + +The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one. + +We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane. + +Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.--_La Lumiere Electrique_. + + * * * * * + + + + +HISTOLOGICAL METHODS. + + +A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required. + +Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly. + +Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol. + +The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol. + +_Section cutting_ machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument. + +A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal. + +When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed. + +With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose. + +[Illustration: FIG. 1.] + +_To out a section by hand_, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush. + +When the object is too small to hold, it is usually _embedded_ in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it. + +Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive. + +Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues. + +Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes. + +Much practice will be required before dexterity is attained. + +_Methods of preserving the tissues_.--All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote. + +The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium. + +The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off. + +_Preservative media_.--Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150°; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine. + +Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased. + +Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained. + +Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts. + +When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement. + +_Preparation for mounting the different tissues_.--To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine. + +Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting. + +The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach. + +The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly. + +The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution. + +Every slide should be of uniform size, and labeled. The usual size is 3×1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required. + + * * * * * + + + + +LIFE HISTORY OF A NEW SEPTIC ORGANISM. + + +At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice +versa_, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form--extending over four years--he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of _Bacterium termo_, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms--one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90° to 95° F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements. + +The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146° F., the highest point endured +by the germs was 190° F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the _modus operandi_ was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law. + + * * * * * + + + + +WINTER AND THE INSECTS. + + +For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellae, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick. + +[Illustration: GREEN WOODPECKER SEARCHING FOR INSECTS.] + +The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line--this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil. + +I now come to the effects of this severe cold upon the insects. + +The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellae, in view of the +previous rarity of the individuals belonging to this family. + +We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvae, pass this season upon the earth +enveloped in a silken envelope, or, like the larvae of the Noctuellae, +between dead leaves or upon the ground itself. + +On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvae and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvae of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera. + +It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvae. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulae are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvae and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans--the wood lice. + +During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvae and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvae are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared. + +In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvae feed and hibernate in the open air a few species of +Noctuellae, whose larvae live buried in the earth, are always abundant. The +country is relatively rich in spices of _Tortrix_, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.--_C.G. Barret, in Science et Nature_. + + * * * * * + + + + +SILK WORM EGGS. + + +Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called _flacherie_, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs: + +[Illustration] + +For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennae, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths. + +There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3×6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room. + +The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day. + +When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered. + + * * * * * + + +Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine. + + * * * * * + +[NATURE.] + + + + +DETERMINING THE MEAN DENSITY OF THE EARTH. + + +In _Nature_ for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the _Nature_ (Jan. 15. p. 260) report of the +_Proceedings_ of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method. + +Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings. + +A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G. + +[Illustration] + +In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance. + +The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary. + +ARTHUR KONIG. + +FRANZ RICHARZ. + +Berlin, Physical Institute of the University, March 15. + + * * * * * + + + + +PHYSICS WITHOUT APPARATUS. + + +_The Porosity and Permeability of Bodies._--Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are _impermeable_, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so _penetrating_. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action. + +[Illustration: Fig. 1.--EXPERIMENT UPON THE PERMEABILITY OF BODIES.] + +_A Hot Air Balloon_.--Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.--_La Nature_. + +[Illustration: Fig. 2.--PRINCIPLE OF THE HOT AIR BALLOON.] + + * * * * * + + + + +THE CASINO AT MONTE CARLO. + + +The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea. + +[Illustration: THE CASINO AT MONTE CARLO.] + +Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces. + +But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player. + +It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined. + + * * * * * + + + + +ON AN EXPRESS ENGINE. + + +It is a somewhat unpromising morning--the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance. + +So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead--the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed--it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades--for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart--where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.--_Saturday Review_. + + * * * * * + + +The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process. + + * * * * * + + + + +ERYTHROXYLON. + +[Footnote: From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.] + + +COCA. + +The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics. + +The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied. + +Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago. + +The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in _The Lancet_ of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body." + +Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages. + +There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.[9] + +[Footnote 9: An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.] + +The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle--namely, caffeine--could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons. + +In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by. + +An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence. + +Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him. + +The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect. + +Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 2½ grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning. + +This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken. + +The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 2½ drachms did give a +definite effect, and a subsequent dose of 2½ fluid drachms of a well made +fluid extract of coca gave about the same effect as 2½ grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine. + +Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained. + +The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the _American Journal of +Pharmacy_, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows: + +Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent. + +Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory. + +Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid. + +From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process. + +Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle. + + * * * * * + + + + +THE MELLOCO. + + +ULLUCUS TUBEROSA.--Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were. + +[Illustration: MELLOCO TUBERS.] + +We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the _Gardeners' Chronicle_ for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49°." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50° in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements. + +Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers--such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the _Gardeners' Chronicle_ for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.--_W. Waston, Kew; +The Gardeners' Chronicle_. + + * * * * * + + +A catalogue, containing brief notices of many important scientific papers +heretofore published in the SUPPLEMENT, may be had gratis at this office. + + + * * * * * + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + +PUBLISHED WEEKLY. + +TERMS OF SUBSCRIPTION, $5 A YEAR. + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of THE SUPPLEMENT, from the commencement, January 1, +1876, can be had. Price, 10 cents each. + +All the back volumes of THE SUPPLEMENT can likewise be supplied. Two +volumes are issued yearly. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 492, June 6, 1885 + +Author: Various + +Release Date: June 2, 2004 [EBook #12490] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team + + + + + +</pre> + +<p class="ctr"><a href="./illustrations/1a.png"><img src="./illustrations/1a_th.jpg" alt="TITLE"></a></p> + +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 492</h1> +<h2>NEW YORK, JUNE 6, 1885</h2> +<h4>Scientific American Supplement. Vol. XIX, No. 492.</h4> +<h4>Scientific American established 1845</h4> +<h4>Scientific American Supplement, $5 a year.</h4> +<h4>Scientific American and Supplement, $7 a year.</h4> +<hr> +<table summary="Contents" border="0" cellspacing="5"> +<tr> +<th colspan="2">TABLE OF CONTENTS.</th> +</tr> +<tr> +<td valign="top">I.</td> +<td><a href="#1"> +ENGINEERING AND MECHANICS.—The New Spanish Artillery.—2 + engravings. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#2"> +Qualitative Tests for Steel Rails.—By L. TETMAJER. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#3"> +A New Form of Small Bessemer Plant.—By A. TRAPPEN. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#4"> +Triple Compound Engines.—A paper read by A.E. SEATON + before the Institution of Naval Architects. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#5"> +Early History of the Steam Jack. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#6"> +Bridge over the River Adige, at Verona.—13 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#7"> +Pumping Machinery.—Mine pumps.—Direct acting steam pumps. + By E.D. LEAVITT. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#8"> + Improved Gun Pressure Gauge.—2 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#9"> +Measuring the Thickness of Boiler Plates. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#32"> + On an Express Engine. +</a></td> +</tr> +<tr> +<td valign="top">II.</td> +<td><a href="#10"> +TECHNOLOGY.—Improved Plaiting Machine.—With engraving. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#11"> + Self-acting Shuttle Guard.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#12"> +Ruler and Triangle for Hatching. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#13"> +The Distillation of Sea Water.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#14"> +Aids to Correct Exposure on Photographic Plates.—An + interesting paper by W. GOODMAN. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#15"> +Isochromatic Photography.—By FRED. E. IVES.—2 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#16"> +Distortion from Expansion of the Paper in Photography. +</a></td> +</tr> +<tr> +<td valign="top">III.</td> +<td><a href="#17"> +ELECTRICITY, ETC.—On the Fritts Selenium Cells and + Batteries.—A paper read before the American Association + by C.E. FRITTS. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#18"> +Electricity Applied to the Manufacture of Varnish.—2 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#19"> +Naglo Brothers' Telephone System.—3 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#20"> +The Gerard Electric Lamp.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#21"> +A New Reflecting Galvanometer.—3 figures. +</a></td> +</tr> +<tr> +<td valign="top">IV.</td> +<td><a href="#22"> +ART AND ARCHITECTURE.—Groups of Statuary for the Pediment + of the House of Parliament in Vienna.—2 engravings. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#23"> +The Casino at Monte Carlo.—An engraving. +</a></td> +</tr> +<tr> +<td valign="top">V.</td> +<td><a href="#24"> +PHYSICS.—Determining the Density of the Earth.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#25"> +Physics without Apparatus.—The Porosity and Permeability of + Bodies.—A Hot Air Balloon.—2 engravings. +</a></td> +</tr> +<tr> +<td valign="top">VI.</td> +<td><a href="#26"> +NATURAL HISTORY.—Winter and the Insects.—An engraving. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#27"> +Silk Worm Eggs.—With engraving. +</a></td> +</tr> +<tr> +<td valign="top">VII.</td> +<td><a href="#28"> +HORTICULTURE.—The Melleco.—Ullucus tuberosa.—With + engraving. +</a></td> +</tr> +<tr> +<td valign="top">VIII.</td> +<td><a href="#29"> +PHYSIOLOGY, MEDICINE, ETC.—Histological Methods.—Section + cutting machines.—Methods of preserving the + tissues.—Preservative media.—Preparation for mounting + tissues.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#30"> + Life History of a New Septic Organism. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#31"> +Erythroxylon Coca as a Therapeutic Agent.—By Dr. E.R. SQUIBB. +</a></td> +</tr> +</table> + +<hr> + +<p><a name="1"></a></p> +<h2>NEW SPANISH ARTILLERY.</h2> + +<p>The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon.</p> + +<p class="ctr"><a href="./illustrations/1b.png"><img src="./illustrations/1b_th.jpg" alt=" NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS."></a></p><p class="ctr"> NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.</p> + +<p>We give engravings from photographs, as presented in <i>La Illustracion +Española</i>. These guns are breech loaders, of steel, 30½ centimeters +caliber, or 12 inches, 49 tons weight.</p> + +<p class="ctr"><a href="./illustrations/1c.png"><img src="./illustrations/1c_th.jpg" alt=" NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS."></a></p><p class="ctr"> NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.</p> + +<p>One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness.</p> + +<hr> + +<p><a name="2"></a></p> +<h2>QUALITATIVE TESTS FOR STEEL RAILS.</h2> + +<h3>By Mr. L. TETMAJER.</h3> + +<p>This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice.</p> + +<p>The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same.</p> + +<p>The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensücherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.—<i>Stahl und Eisen</i>, vol. iv., page 608; through +<i>Proc. Inst. Civ. Eng</i>.</p> + +<hr> + +<p><a name="3"></a></p> +<h2>A NEW FORM OF SMALL BESSEMER PLANT.</h2> + +<h3>By Mr. A. TRAPPEN.</h3> + +<p>The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift.</p> + +<p>The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure.</p> + +<p>The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at £2,050 +to £2,100; and that of the steam boiler, £325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.—<i>Stahl und +Eisen</i>, vol. iv., page 524; through <i>Proc. Inst. Civ. Eng</i>.</p> + +<hr> + +<p><a name="4"></a></p> +<h2>TRIPLE COMPOUND ENGINES.<a name="FNanchor1"></a><a href="#Footnote_1"><sup>[1]</sup></a></h2> + +<h3>By Mr. A.E. SEATON.</h3> + +<p>My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small.</p> + +<p>The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows:</p> + +<pre> + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 +</pre> + +<p>And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment.</p> + +<p>After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent.</p> + +<p>In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day.</p> + +<p>The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure.</p> + +<p>So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 20½ inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear.</p> + +<p>I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +½ knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other.</p> + +<p>We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 11½ inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen.</p> + +<p>I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands.</p> + +<a name="Footnote_1"></a><a href="#FNanchor1">[1]</a><div class=note>Paper read before the Institution of Naval Architects, March +27, 1885.</div> + +<hr> + +<p><a name="5"></a></p> +<h2>EARLY HISTORY OF THE STEAM JACK.</h2> + +<p><i>To the Editor of the Scientific American:</i></p> + +<p>A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack."</p> + +<p>Says Mr. J.G. Briggs, in the <i>American Engineer:</i> "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.—a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country—if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment <i>patent</i>, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the <i>Hub</i>, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston.</p> + +<p>Trusting I have not wearied you, I am,</p> + +<p>ANNA M. BAILEY.</p> + +<p>Bleak House, Lynn, Mass., May 12.</p> + +<h3>COPY OF PATENT.</h3> + +<p><i>United States</i>.</p> + +<p>To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. G<sup>o</sup>. WASHINGTON.</p> + +<p>By the President,</p> + +<p>TH. JEFFERSON.</p> + +<p>CITY OF PHILADELPHIA, February 23, 1792.</p> + +<p>I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act.</p> + +<p>EDM. RANDOLPH,</p> + +<p><i>Attorney-General of the U.S.</i></p> + +<p>[SEAL.]</p> + +<hr> + +<p><a name="6"></a></p> +<h2>BRIDGE AT VERONA.</h2> + +<p class="ctr"><a href="./illustrations/3a.png"><img src="./illustrations/3a_th.jpg" alt=" BRIDGE OVER THE RIVER ADIGE, AT VERONA."></a></p><p class="ctr"> BRIDGE OVER THE RIVER ADIGE, AT VERONA.</p> + +<p>The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge:</p> + +<pre> + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 9¾ +Width of bridge 37 4¾ +Depth of arched girders 4 7 +</pre> + +<p>The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 <i>l.</i>; the abutments cost 3,600<i>l.</i>, +making the total outlay on the structure 12,000<I>l</I>. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.—<i>Engineering</i>.</p> + +<p class="ctr"><a href="./illustrations/3b.png"><img src="./illustrations/3b_th.jpg" alt=" BRIDGE OVER THE RIVER ADIGE, AT VERONA."></a></p><p class="ctr"> BRIDGE OVER THE RIVER ADIGE, AT VERONA.</p> + +<hr> + +<p><a name="7"></a></p> +<h2>PUMPING MACHINERY.<a name="FNanchor2"></a><a href="#Footnote_2"><sup>[1]</sup></a></h2> + +<h3>By E.D. LEAVITT, JR., Cambridgeport, Mass.</h3> + +<h3>MINE PUMPING MACHINERY.</h3> + +<p>One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine.</p> + +<p>At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia WaterWorks; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines.</p> + +<p>In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well.</p> + +<p>The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States.</p> + +<p>A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned.</p> + +<p>Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet.</p> + +<p>The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps.</p> + +<p>The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 22½ feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine.</p> + +<p>In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 4½ inches thickness of metal. The pump rock shaft +is 39 feet 4½ inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine.</p> + +<p>The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft.</p> + +<p>The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to ½ inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute.</p> + +<p>The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 17½ inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same.</p> + +<p>The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections.</p> + +<p>The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links.</p> + +<p>The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 5¼ inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity.</p> + +<p>The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory.</p> + +<h3>DIRECT ACTING STEAM PUMPS.</h3> + +<p>This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined.</p> + +<p>The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish.</p> + +<a name="Footnote_2"></a><a href="#FNanchor2">[1]</a><div class=note>A paper read at the Montreal Meeting of the British +Association.</div> + +<hr> + +<p><a name="8"></a></p> +<h2>IMPROVED GUN PRESSURE GAUGE.</h2> + +<p>The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor.</p> + +<p class="ctr"><a href="./illustrations/4a.png"><img src="./illustrations/4a_th.jpg" alt=" IMPROVED GUN PRESSURE GAUGE."></a></p><p class="ctr"> IMPROVED GUN PRESSURE GAUGE.</p> + +<p>Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb.</p> + +<p>It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with.</p> + +<p>The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds.</p> + +<p>The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice.</p> + +<p>This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder.</p> + +<hr> + +<p><a name="10"></a></p> +<h2>IMPROVED PLAITING MACHINE.</h2> + +<p>The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length.</p> + +<p class="ctr"><a href="./illustrations/5a.png"><img src="./illustrations/5a_th.jpg" alt=" IMPROVED PLAITING MACHINE."></a></p><p class="ctr"> IMPROVED PLAITING MACHINE.</p> + +<p>To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner:</p> + +<p>Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G<sup>1</sup> G<sup>1</sup>. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires.</p> + +<p>It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.—<i>Tex. Manfr</i>.</p> + +<hr> + +<p><a name="11"></a></p> +<h2>SELF-ACTING SHUTTLE GUARD.</h2> + +<p class="ctr"><a href="./illustrations/5b.png"><img src="./illustrations/5b_th.jpg" alt=" SELF-ACTING SHUTTLE GUARD."></a></p><p class="ctr"> SELF-ACTING SHUTTLE GUARD.</p> + +<p>The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers.</p> + +<hr> + +<p><a name="12"></a></p> +<h2>RULER AND TRIANGLE FOR HATCHING.</h2> + +<p>The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45°, but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former.</p> + +<p class="ctr"><a href="./illustrations/5c.png"><img src="./illustrations/5c_th.jpg" alt=" RULER AND TRIANGLE FOR HATCHING."></a></p><p class="ctr"> RULER AND TRIANGLE FOR HATCHING.</p> + +<p>The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.—<i>Chronique Industrielle</i>.</p> + +<hr> + +<p><a name="13"></a></p> +<h2>THE DISTILLATION OF SEA WATER.</h2> + +<p>The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service.</p> + +<p>Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process.</p> + +<p>In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried.</p> + +<p>Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 4½ cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes—in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser.</p> + +<p class="ctr"><a href="./illustrations/6a.png"><img src="./illustrations/6a_th.jpg" alt=""></a></p> + +<p>Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order.</p> + +<p>As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +2¼ gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance.</p> + +<p>Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is <i>said</i> are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.—<i>The Engineer</i>.</p> + +<hr> + +<p><a name="14"></a></p> +<h2>AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES.<a name="FNanchor3"></a><a href="#Footnote_3"><sup>[1]</sup></a></h2> + +<p>With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative.</p> + +<pre> + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +</pre> + +<p>The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum.</p> + +<p>The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done.</p> + +<p>Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed.</p> + +<p>The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both.</p> + +<p>The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens.</p> + +<p>The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size.</p> + +<p>First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch.</p> + +<p>Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 7½ in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two.</p> + +<p>We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table.</p> + +<p>We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium <i>nitrite</i> (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough.</p> + +<p>However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass.</p> + +<p>Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done—kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer.</p> + +<p>When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right.</p> + +<p>Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table.</p> + +<p>You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only.</p> + +<p>On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures.</p> + +<p>I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous.</p> + +<p>The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you <i>may</i> make a negative of an overexposed plate, but never +of an underexposed one.</p> + +<a name="Footnote_3"></a><a href="#FNanchor3">[1]</a><div class=note> We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.</div> + +<hr> + +<p><a name="15"></a></p> +<h2>ISOCHROMATIC PHOTOGRAPHY.<a name="FNanchor4"></a><a href="#Footnote_4"><sup>[1]</sup></a></h2> + +<h3>By FRED. E. IVES.</h3> + +<p>It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography.</p> + +<p>Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process.</p> + +<p>In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, <i>why</i> it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives—blue, yellow, and red—would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow.</p> + +<p>Having succeeded perfectly in my undertakings, I published my discovery +in 1879,<a name="FNanchor5"></a><a href="#Footnote_5"><sup>[2]</sup></a> explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.<a name="FNanchor6"></a><a href="#Footnote_6"><sup>[3]</sup></a></p> + +<p>So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,<a name="FNanchor7"></a><a href="#Footnote_7"><sup>[4]</sup></a> +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness.</p> + +<p>My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.<a name="FNanchor8"></a><a href="#Footnote_8"><sup>[5]</sup></a> A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure.</p> + +<p>My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement.</p> + +<p>The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer.</p> + +<p class="ctr"><a href="./illustrations/7a.png"><img src="./illustrations/7a_th.jpg" alt=" IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY."></a></p><p class="ctr"> IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.</p> + +<p>In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank.</p> + +<p>I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them.</p> + +<p>To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered.</p> + +<p>Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness.</p> + +<p>I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination.</p> + +<p>Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but <i>comparatively insensitive to +red</i>, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process.</p> + +<a name="Footnote_4"></a><a href="#FNanchor4">[1]</a><div class=note>Read at the stated meeting of the Franklin Institute, March +18, 1885.</div> + +<a name="Footnote_5"></a><a href="#FNanchor5">[2]</a><div class=note><i>Philadelphia Photographer</i>, December, 1879, p. 365.</div> + +<a name="Footnote_6"></a><a href="#FNanchor6">[3]</a><div class=note> I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the <i>Photo. News</i>, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +<i>Photo. News</i>, Nov. 1883, p. 747.</div> + +<a name="Footnote_7"></a><a href="#FNanchor7">[4]</a><div class=note><i>Photo. News</i>, London, September 5, 1884, p. 566, and <i>Year +Book of Photography</i> for 1885, p. 111.</div> + +<a name="Footnote_8"></a><a href="#FNanchor8">[5]</a><div class=note>I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from <i>fresh</i> +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.</div> + +<hr> + +<p><a name="16"></a></p> +<h2>DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY.</h2> + +<p>The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper.</p> + +<p>When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears.</p> + +<p>If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness—owing to +this particular distortion—of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied.</p> + +<p>Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby.</p> + +<p>To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight—perhaps imperceptible—compared with that existing +when the prints are mounted wet. I may mention, <i>en passant</i>, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system.</p> + +<p>The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion.</p> + +<p>For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there.</p> + +<p>Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion.</p> + +<p>A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass.</p> + +<p>Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled.</p> + +<p>The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.—<i>W.E. +Debenham, in Br. Jour. of Photography</i>.</p> + +<hr> + +<p><a name="9"></a></p> +<h2>MEASURING THE THICKNESS OF BOILER PLATES.</h2> + +<p>An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy.</p> + +<hr> + +<p><a name="22"></a></p> +<h2>GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA.</h2> + +<p>The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer.</p> + +<p class="ctr"><a href="./illustrations/8a.png"><img src="./illustrations/8a_th.jpg" alt=" STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—SCIENCE AND LITERATURE. (GROUP TO THE LEFT.)"></a></p><p class="ctr"> STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—SCIENCE AND LITERATURE. (GROUP TO THE LEFT.)</p> + +<p>The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government.</p> + +<p>Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows.</p> + +<p>A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry.</p> + +<p>Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce.</p> + +<p class="ctr"><a href="./illustrations/9a.png"><img src="./illustrations/9a_th.jpg" alt=" STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—INDUSTRY AND COMMERCE. (GROUP TO THE RIGHT.)"></a></p><p class="ctr"> STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—INDUSTRY AND COMMERCE. (GROUP TO THE RIGHT.)</p> + +<p>The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.—<i>Illustrirte Zeitung</i>.</p> + +<hr> + +<p><a name="17"></a></p> +<h2>ON THE FRITTS SELENIUM CELLS AND BATTERIES.<a name="FNanchor9"></a><a href="#Footnote_9"><sup>[1]</sup></a></h2> + +<h3>By C.E. FRITTS, 42 Nassau St., New York, N.Y.</h3> + +<p>In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface.</p> + +<p>My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure.</p> + +<p>During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a <i>transparent conductor of electricity</i>, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.<a name="FNanchor10"></a><a href="#Footnote_10"><sup>[2]</sup></a> My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired.</p> + +<p>By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following:</p> + +<p>1. <i>Their sensitiveness to light</i> is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells.</p> + +<p>It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 <i>per cent</i>. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained <i>less than 3/10 of 1 per cent</i>. of the original +resistance of the selenium in dark.</p> + +<p>In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act through +the gold, in conjunction, their forces are united; and, as every atom of +the selenium is affected by the light, owing to the extreme thinness of +the plate, we have the full effect shown in the measurements.</p> + +<pre> +----------------------------------------------------------------- + TABLE A. + SENSITIVENESS TO LIGHT. +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23<a name="FNanchor11"></a><a href="#Footnote_11">³</a> |5 " | 14,000 | 170 | 82.3 " " + " 24<a name="FNanchor12"></a><a href="#Footnote_12">⁴</a> |5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129<a href="#Footnote_11">³</a> |5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- +</pre> + +<p>Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not.</p> + +<p><i>Mode of measuring cells</i>.—So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently.</p> + +<p>The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison.</p> + +<p>2. <i>The kind of battery employed</i> has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the <i>resistance</i> +of a cell, but it is not clear how or why it should affect the +<i>sensitiveness of selenium to light</i>.</p> + +<p>"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?"</p> + +<p>One year ago I made the foregoing suggestion in a paper on <i>A New Form of +Selenium Cell</i>, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells.</p> + +<p>3. <i>The two surfaces of the selenium act differently toward currents</i> +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results.</p> + +<pre> +------------------------------------------------------------------- + TABLE B. + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- +</pre> + +<p>The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark.</p> + +<p>4. <i>Sensitiveness to change of battery power</i>.—My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified—</p> + +<p>(a) By changing the potential or electromotive force of the current +through the cell.</p> + +<p>(b) By changing the "quantity" of the battery or current.</p> + +<p>(c) By putting more or less resistance in the circuit.</p> + +<p>(d) By dividing the current, by one or more branch circuits or shunts +around the cell.</p> + +<p>(e) By varying the resistance in any or all of said circuits.</p> + +<p>A cell whose resistance becomes greater as the battery power becomes +greater, and <i>vice versa</i>, I call an "L B cell" signifying <i>Like the +Battery power</i>. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and <i>vice +versa</i>, being <i>Unlike the Battery power</i>, or current strength.</p> + +<p>These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change.</p> + +<p>The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms.</p> + +<pre> +--------------------------------------------------------------- + TABLE C. + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123<a name="FNanchor13"></a><a href="#Footnote_13">⁵</a> | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- +</pre> + +<p>The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark.</p> + +<p>5. <i>Dual state of selenium</i>.—My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable.</p> + +<p>In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another.</p> + +<p>The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed?</p> + +<p>6. <i>Radio-electric current generators</i>.—My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means.</p> + +<p>The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted.</p> + +<p>I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required.</p> + +<p>7. <i>Singing and speaking cells</i>.—When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current—and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit.</p> + +<p>My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation.</p> + +<h3>GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS.</h3> + +<p>From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells."</p> + +<p>The property of sensitiveness to light is independent of the power to +generate current by exposure to light—the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat.</p> + +<p>The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light—their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them.</p> + +<p>The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light.</p> + +<p><i>Constancy of the resistance</i>.—A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms—sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant.</p> + +<p>As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness.</p> + +<p><i>Practical applications</i>.—There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale.</p> + +<p>The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my</p> + +<p><i>Photometer</i>.—The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights—the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light.</p> + +<p>This arrangement leaves untouched the old difficulty in photometry, that +arising from the different <i>colors</i> of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration.</p> + +<p><i>Photo-electric regulator</i>.—My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small.</p> + +<p>In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries.</p> + +<a name="Footnote_9"></a><a href="#FNanchor9">[1]</a><div class=note>Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.</div> + +<a name="Footnote_10"></a><a href="#FNanchor10">[2]</a><div class=note>The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.</div> + +<a name="Footnote_11"></a><a href="#FNanchor11">[3]</a><div class=note>Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.</div> + +<a name="Footnote_12"></a><a href="#FNanchor12">[4]</a><div class=note>No. 24 was measured with a bridge multiplier of 6 to 1.</div> + +<a name="Footnote_13"></a><a href="#FNanchor13">[5]</a><div class=note>This measurement was obtained with 8 elements.</div> + +<hr> + +<p><a name="18"></a></p> +<h2>ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH.</h2> + +<p>Messrs. Müthel & Lütche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on.</p> + +<p>The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures.</p> + +<p>The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever.</p> + +<p class="ctr"><a href="./illustrations/11a.png"><img src="./illustrations/11a_th.jpg" alt=" FIGS. 1 AND 2."></a></p><p class="ctr"> FIGS. 1 AND 2.</p> + +<p>The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60° and 80°. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone.</p> + +<p>When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.—<i>La Lumiere +Electrique.</i></p> + +<hr> + +<p><a name="19"></a></p> +<h2>NAGLO BROTHERS' TELEPHONE SYSTEM.</h2> + +<p>We borrow from the <i>Elektrotechnische Zeitung</i> the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f<sub>2</sub>. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f<sub>1</sub>. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle.</p> + +<p class="ctr"><a href="./illustrations/11b.png"><img src="./illustrations/11b_th.jpg" alt=" FIG. 1."></a></p><p class="ctr"> FIG. 1.</p> + +<p>Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve.</p> + +<p>This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f<sub>2</sub> p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling.</p> + +<p class="ctr"><a href="./illustrations/11c.png"><img src="./illustrations/11c_th.jpg" alt=" FIGS. 2 AND 3."></a></p><p class="ctr"> FIGS. 2 AND 3.</p> + +<p>Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.—<i>La Lumiere Electrique</i>.</p> + +<hr> + +<p><a name="20"></a></p> +<h2>THE GERARD ELECTRIC LAMP.</h2> + +<p>In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage.</p> + +<p>This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp:</p> + +<pre> + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 +</pre> + +<p>It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example—this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps.</p> + +<p class="ctr"><a href="./illustrations/11d.png"><img src="./illustrations/11d_th.jpg" alt=" GERARD'S INCANDESCENT LAMP."></a></p><p class="ctr"> GERARD'S INCANDESCENT LAMP.</p> + +<p>The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature.</p> + +<p>The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.—<i>Le Genie +Civil</i>.</p> + +<hr> + +<p><a name="21"></a></p> +<h2>A NEW REFLECTING GALVANOMETER.</h2> + +<p>Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106° with each other, so that the planes containing the axes of the +bobbins make an angle of about 74°. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated.</p> + +<p class="ctr"><a href="./illustrations/11e.png"><img src="./illustrations/11e_th.jpg" alt=" FIG. 1. GRAY'S GALVANOMETER."></a></p><p class="ctr"> FIG. 1. GRAY'S GALVANOMETER.</p> + +<p>The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections.</p> + +<p>In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite.</p> + +<p class="ctr"><a href="./illustrations/11f.png"><img src="./illustrations/11f_th.jpg" alt=" FIG. 2."></a></p><p class="ctr"> FIG. 2.</p> + +<p>The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread.</p> + +<p>The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T<sup>1</sup>, T<sub>2</sub>, and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite.</p> + +<p>Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation.</p> + +<p>In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10<sup>4</sup> to 10<sup>5</sup> megohms could be measured +by the use of a pile of 120 daniells.</p> + +<p>The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier.</p> + +<p>The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one.</p> + +<p>We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane.</p> + +<p>Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.—<i>La Lumiere Electrique</i>.</p> + +<hr> + +<p><a name="29"></a></p> +<h2>HISTOLOGICAL METHODS.</h2> + +<p>A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required.</p> + +<p>Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly.</p> + +<p>Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol.</p> + +<p>The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol.</p> + +<p><i>Section cutting</i> machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument.</p> + +<p>A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal.</p> + +<p>When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed.</p> + +<p>With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose.</p> + +<p class="ctr"><a href="./illustrations/12a.png"><img src="./illustrations/12a_th.jpg" alt=" FIG. 1."></a></p><p class="ctr"> FIG. 1.</p> + +<p><i>To out a section by hand</i>, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush.</p> + +<p>When the object is too small to hold, it is usually <i>embedded</i> in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it.</p> + +<p>Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive.</p> + +<p>Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues.</p> + +<p>Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes.</p> + +<p>Much practice will be required before dexterity is attained.</p> + +<p><i>Methods of preserving the tissues</i>.—All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote.</p> + +<p>The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium.</p> + +<p>The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off.</p> + +<p><i>Preservative media</i>.—Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150°; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine.</p> + +<p>Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased.</p> + +<p>Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained.</p> + +<p>Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts.</p> + +<p>When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement.</p> + +<p><i>Preparation for mounting the different tissues</i>.—To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine.</p> + +<p>Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting.</p> + +<p>The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach.</p> + +<p>The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly.</p> + +<p>The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution.</p> + +<p>Every slide should be of uniform size, and labeled. The usual size is 3×1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required.</p> + +<hr> + +<p><a name="30"></a></p> +<h2>LIFE HISTORY OF A NEW SEPTIC ORGANISM.</h2> + +<p>At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of <i>Bacillus anthracis</i> and <i>Bacillus subtilis</i>, and <i>vice +versa</i>, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form—extending over four years—he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of <i>Bacterium termo</i>, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms—one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90° to 95° F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements.</p> + +<p>The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146° F., the highest point endured +by the germs was 190° F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the <i>modus operandi</i> was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law.</p> + +<hr> + +<p><a name="26"></a></p> +<h2>WINTER AND THE INSECTS.</h2> + +<p>For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellæ, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick.</p> + +<p class="ctr"><a href="./illustrations/13a.png"><img src="./illustrations/13a_th.jpg" alt=" GREEN WOODPECKER SEARCHING FOR INSECTS."></a></p><p class="ctr"> GREEN WOODPECKER SEARCHING FOR INSECTS.</p> + +<p>The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line—this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil.</p> + +<p>I now come to the effects of this severe cold upon the insects.</p> + +<p>The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellæ, in view of the +previous rarity of the individuals belonging to this family.</p> + +<p>We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvæ, pass this season upon the earth +enveloped in a silken envelope, or, like the larvæ of the Noctuellæ, +between dead leaves or upon the ground itself.</p> + +<p>On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvæ and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvæ of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera.</p> + +<p>It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvæ. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulæ are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvæ and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans—the wood lice.</p> + +<p>During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvæ and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvæ are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared.</p> + +<p>In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvæ feed and hibernate in the open air a few species of +Noctuellæ, whose larvæ live buried in the earth, are always abundant. The +country is relatively rich in spices of <i>Tortrix</i>, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.—<i>C.G. Barret, in Science et Nature</i>.</p> + +<hr> + +<p><a name="27"></a></p> +<h2>SILK WORM EGGS.</h2> + +<p>Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called <i>flacherie</i>, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs:</p> + +<p class="ctr"><a href="./illustrations/13b.png"><img src="./illustrations/13b_th.jpg" alt=""></a></p> + +<p>For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennæ, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths.</p> + +<p>There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3×6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room.</p> + +<p>The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day.</p> + +<p>When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered.</p> + +<hr> + +<p>Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine.</p> + +<hr> + +<h3>[NATURE.]</h3> + +<p><a name="24"></a></p> +<h2>DETERMINING THE MEAN DENSITY OF THE EARTH.</h2> + +<p>In <i>Nature</i> for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the <i>Nature</i> (Jan. 15. p. 260) report of the +<i>Proceedings</i> of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method.</p> + +<p>Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings.</p> + +<p>A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G.</p> + +<p class="ctr"><a href="./illustrations/14a.png"><img src="./illustrations/14a_th.jpg" alt=""></a></p> + +<p>In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance.</p> + +<p>The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary.</p> + +<p>ARTHUR KONIG.</p> + +<p>FRANZ RICHARZ.</p> + +<p>Berlin, Physical Institute of the University, March 15.</p> + +<hr> + +<p><a name="25"></a></p> +<h2>PHYSICS WITHOUT APPARATUS.</h2> + +<p><i>The Porosity and Permeability of Bodies.</i>—Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are <i>impermeable</i>, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so <i>penetrating</i>. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action.</p> + +<p class="ctr"><a href="./illustrations/14b.png"><img src="./illustrations/14b_th.jpg" alt=" Fig. 1.—EXPERIMENT UPON THE PERMEABILITY OF BODIES."></a></p><p class="ctr"> Fig. 1.—EXPERIMENT UPON THE PERMEABILITY OF BODIES.</p> + +<p><i>A Hot Air Balloon</i>.—Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.—<i>La Nature</i>.</p> + +<p class="ctr"><a href="./illustrations/14c.png"><img src="./illustrations/14c_th.jpg" alt=" Fig. 2.—PRINCIPLE OF THE HOT AIR BALLOON."></a></p><p class="ctr"> Fig. 2.—PRINCIPLE OF THE HOT AIR BALLOON.</p> + +<hr> + +<p><a name="23"></a></p> +<h2>THE CASINO AT MONTE CARLO.</h2> + +<p>The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea.</p> + +<p class="ctr"><a href="./illustrations/14d.png"><img src="./illustrations/14d_th.jpg" alt=" THE CASINO AT MONTE CARLO."></a></p><p class="ctr"> THE CASINO AT MONTE CARLO.</p> + +<p>Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces.</p> + +<p>But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player.</p> + +<p>It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined.</p> + +<hr> + +<p><a name="32"></a></p> +<h2>ON AN EXPRESS ENGINE.</h2> + +<p>It is a somewhat unpromising morning—the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance.</p> + +<p>So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead—the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed—it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades—for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart—where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.—<i>Saturday Review</i>.</p> + +<hr> + +<p>The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process.</p> + +<hr> + +<p><a name="31"></a></p> +<h2>ERYTHROXYLON.<a name="FNanchor14"></a><a href="#Footnote_14"><sup>[1]</sup></a></h2> + +<h3>COCA.</h3> + +<p>The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics.</p> + +<p>The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied.</p> + +<p>Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago.</p> + +<p>The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in <i>The Lancet</i> of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body."</p> + +<p>Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages.</p> + +<p>There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.<a name="FNanchor15"></a><a href="#Footnote_15"><sup>[2]</sup></a></p> + +<p>The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle—namely, caffeine—could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons.</p> + +<p>In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by.</p> + +<p>An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence.</p> + +<p>Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him.</p> + +<p>The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect.</p> + +<p>Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 2½ grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning.</p> + +<p>This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken.</p> + +<p>The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 2½ drachms did give a +definite effect, and a subsequent dose of 2½ fluid drachms of a well made +fluid extract of coca gave about the same effect as 2½ grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine.</p> + +<p>Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained.</p> + +<p>The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the <i>American Journal of +Pharmacy</i>, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows:</p> + +<p>Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent.</p> + +<p>Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory.</p> + +<p>Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid.</p> + +<p>From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process.</p> + +<p>Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle.</p> + +<a name="Footnote_14"></a><a href="#FNanchor14">[1]</a><div class=note>From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.</div> + +<a name="Footnote_15"></a><a href="#FNanchor15">[2]</a><div class=note>An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.</div> + +<hr> + +<p><a name="28"></a></p> +<h2>THE MELLOCO.</h2> + +<p>ULLUCUS TUBEROSA.—Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were.</p> + +<p class="ctr"><a href="./illustrations/16a.png"><img src="./illustrations/16a_th.jpg" alt=" MELLOCO TUBERS."></a></p><p class="ctr"> MELLOCO TUBERS.</p> + +<p>We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the <i>Gardeners' Chronicle</i> for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49°." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50° in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements.</p> + +<p>Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers—such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the <i>Gardeners' Chronicle</i> for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.—<i>W. 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cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 492, June 6, 1885 + +Author: Various + +Release Date: June 2, 2004 [EBook #12490] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 492 + + + + +NEW YORK, JUNE 6, 1885. + +Scientific American Supplement. Vol. XIX, No. 492. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + + * * * * * + + +TABLE OF CONTENTS. + +I. ENGINEERING AND MECHANICS.--The New Spanish Artillery.--2 + engravings. + + Qualitative Tests for Steel Rails.--By L. TETMAJER. + + A New Form of Small Bessemer Plant.--By A. TRAPPEN. + + Triple Compound Engines.--A paper read by A.E. SEATON + before the Institution of Naval Architects. + + Early History of the Steam Jack. + + Bridge over the River Adige, at Verona.--13 figures. + + Pumping Machinery.--Mine pumps.--Direct acting steam pumps. + By E.D. LEAVITT. + + Improved Gun Pressure Gauge.--2 figures. + + Measuring the Thickness of Boiler Plates. + + On an Express Engine. + + +II. TECHNOLOGY.--Improved Plaiting Machine.--With engraving. + + Self-acting Shuttle Guard.--1 figure. + + Ruler and Triangle for Hatching. + + The Distillation of Sea Water.--1 figure. + + Aids to Correct Exposure on Photographic Plates.--An + interesting paper by W. GOODMAN. + + Isochromatic Photography.--By FRED. E. IVES.--2 figures. + + Distortion from Expansion of the Paper in Photography. + + +III. ELECTRICITY, ETC.--On the Fritts Selenium Cells and + Batteries.--A paper read before the American Association + by C.E. FRITTS. + + Electricity Applied to the Manufacture of Varnish.--2 figures. + + Naglo Brothers' Telephone System.--3 figures. + + The Gerard Electric Lamp.--1 figure. + + A New Reflecting Galvanometer.--3 figures. + + +IV. ART AND ARCHITECTURE.--Groups of Statuary for the Pediment + of the House of Parliament in Vienna.--2 engravings. + + The Casino at Monte Carlo.--An engraving. + + +V. PHYSICS.--Determining the Density of the Earth.--1 figure. + + Physics without Apparatus.--The Porosity and Permeability of + Bodies.--A Hot Air Balloon.--2 engravings. + + +VI. NATURAL HISTORY.--Winter and the Insects.--An engraving. + + Silk Worm Eggs.--With engraving. + + +VII. HORTICULTURE.--The Melleco.--Ullucus tuberosa.--With + engraving. + + +VIII. PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section + cutting machines.--Methods of preserving the + tissues.--Preservative media.--Preparation for mounting + tissues.--1 figure. + + Life History of a New Septic Organism. + + Erythroxylon Coca as a Therapeutic Agent.--By Dr. E.R. SQUIBB. + + * * * * * + + + + +NEW SPANISH ARTILLERY. + + +The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +We give engravings from photographs, as presented in _La Illustracion +Espanola_. These guns are breech loaders, of steel, 301/2 centimeters +caliber, or 12 inches, 49 tons weight. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness. + + * * * * * + + + + +QUALITATIVE TESTS FOR STEEL RAILS. + +By Mr. L. TETMAJER. + + +This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice. + +The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same. + +The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensuecherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.--_Stahl und Eisen_, vol. iv., page 608; through +_Proc. Inst. Civ. Eng_. + + * * * * * + + + + +A NEW FORM OF SMALL BESSEMER PLANT. + +By Mr. A. TRAPPEN. + + +The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift. + +The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure. + +The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at L2,050 +to L2,100; and that of the steam boiler, L325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.--_Stahl und +Eisen_, vol. iv., page 524; through _Proc. Inst. Civ. Eng_. + + * * * * * + + + + +TRIPLE COMPOUND ENGINES. + +[Footnote: Paper read before the Institution of Naval Architects, March +27, 1885.] + +By Mr. A.E. SEATON. + + +My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small. + +The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows: + + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 + +And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment. + +After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent. + +In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day. + +The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure. + +So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 201/2 inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear. + +I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +1/2 knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other. + +We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 111/2 inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen. + +I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands. + + * * * * * + + + + +EARLY HISTORY OF THE STEAM JACK. + +_To the Editor of the Scientific American:_ + + +A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack." + +Says Mr. J.G. Briggs, in the _American Engineer:_ "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.--a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country--if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment _patent_, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the _Hub_, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston. + +Trusting I have not wearied you, I am, + +ANNA M. BAILEY. + +Bleak House, Lynn, Mass., May 12. + + +COPY OF PATENT. + +_United States_. + +To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. Go. WASHINGTON. + +By the President, + +TH. JEFFERSON. + + +CITY OF PHILADELPHIA, February 23, 1792. + +I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act. + +EDM. RANDOLPH, + +_Attorney-General of the U.S._ + +[SEAL.] + + * * * * * + + + + +BRIDGE AT VERONA. + + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge: + + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 93/4 +Width of bridge 37 43/4 +Depth of arched girders 4 7 + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 _l._; the abutments cost 3,600_l._, +making the total outlay on the structure 12,000_l_. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.--_Engineering_. + + * * * * * + + + + +PUMPING MACHINERY. + +[Footnote: A paper read at the Montreal Meeting of the British +Association.] + +By E.D. LEAVITT, JR., Cambridgeport, Mass. + +MINE PUMPING MACHINERY. + + +One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine. + +At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia Water Works; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines. + +In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well. + +The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States. + +A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned. + +Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet. + +The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps. + +The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 221/2 feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine. + +In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 41/2 inches thickness of metal. The pump rock shaft +is 39 feet 41/2 inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine. + +The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft. + +The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to 1/2 inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute. + +The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 171/2 inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same. + +The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections. + +The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links. + +The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 51/4 inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity. + +The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory. + + +DIRECT ACTING STEAM PUMPS. + +This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined. + +The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish. + + * * * * * + + + + +IMPROVED GUN PRESSURE GAUGE. + + +The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor. + +[Illustration: IMPROVED GUN PRESSURE GAUGE.] + +Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb. + +It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with. + +The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds. + +The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice. + +This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder. + + * * * * * + + + + +IMPROVED PLAITING MACHINE. + + +The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length. + +[Illustration: IMPROVED PLAITING MACHINE.] + +To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner: + +Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G' G'. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires. + +It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.--_Tex. Manfr._ + + * * * * * + + + + +SELF-ACTING SHUTTLE GUARD. + + +[Illustration: SELF-ACTING SHUTTLE GUARD.] + +The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers. + + * * * * * + + + + +RULER AND TRIANGLE FOR HATCHING. + + +The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45 deg., but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former. + +[Illustration: RULER AND TRIANGLE FOR HATCHING.] + +The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.--_Chronique Industrielle_. + + * * * * * + + + + +THE DISTILLATION OF SEA WATER. + + +The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service. + +Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process. + +In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried. + +Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 41/2 cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes--in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser. + +[Illustration] + +Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order. + +As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +21/4 gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance. + +Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is _said_ are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.--_The Engineer_. + + * * * * * + + + + +AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES. + +[Footnote: We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.] + + +With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative. + + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ + +The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum. + +The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done. + +Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed. + +The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both. + +The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens. + +The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size. + +First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch. + +Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 71/2 in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two. + +We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table. + +We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium _nitrite_ (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough. + +However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass. + +Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done--kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer. + +When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right. + +Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table. + +You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only. + +On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures. + +I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous. + +The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you _may_ make a negative of an overexposed plate, but never +of an underexposed one. + + * * * * * + + + + +ISOCHROMATIC PHOTOGRAPHY. + +[Footnote: Read at the stated meeting of the Franklin Institute, March +18, 1885.] + +By FRED. E. IVES. + + +It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography. + +Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process. + +In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, _why_ it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives--blue, yellow, and red--would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow. + +Having succeeded perfectly in my undertakings, I published my discovery +in 1879,[1] explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.[2] + +[Footnote 1: _Philadelphia Photographer_, December, 1879, p. 365.] + +[Footnote 2: I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the _Photo. News_, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +_Photo. News_, Nov. 1883, p. 747.] + +So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,[3] +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness. + +[Footnote 3: _Photo. News_, London, September 5, 1884, p. 566, and _Year +Book of Photography_ for 1885, p. 111.] + +My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.[4] A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure. + +[Footnote 4: I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from _fresh_ +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.] + +My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement. + +The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer. + +[Illustration: IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.] + +In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank. + +I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them. + +To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered. + +Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness. + +I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination. + +Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but _comparatively insensitive to +red_, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process. + + * * * * * + + + + +DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY. + + +The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper. + +When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears. + +If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness--owing to +this particular distortion--of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied. + +Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby. + +To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight--perhaps imperceptible--compared with that existing +when the prints are mounted wet. I may mention, _en passant_, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system. + +The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion. + +For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there. + +Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion. + +A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass. + +Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled. + +The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.--_W.E. +Debenham, in Br. Jour. of Photography_. + + * * * * * + + + + +MEASURING THE THICKNESS OF BOILER PLATES. + + +An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy. + + * * * * * + + + + +GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA. + + +The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--SCIENCE +AND LITERATURE. (GROUP TO THE LEFT.)] + +The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government. + +Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows. + +A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry. + +Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--INDUSTRY +AND COMMERCE. (GROUP TO THE RIGHT.)] + +The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.--_Illustrirte Zeitung_. + + * * * * * + + + + +ON THE FRITTS SELENIUM CELLS AND BATTERIES. + +[Footnote: Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.] + +By C.E. FRITTS, 42 Nassau St., New York, N.Y. + + +In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface. + +My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure. + +During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a _transparent conductor of electricity_, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.[5] My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired. + +[Footnote 5: The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.] + +By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following: + +1. _Their sensitiveness to light_ is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells. + +It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 _per cent_. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained _less than 3/10 of 1 per cent_. of the original +resistance of the selenium in dark. + +In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act +through the gold, in conjunction, their forces are united; and, as every +atom of the selenium is affected by the light, owing to the extreme +thinness of the plate, we have the full effect shown in the measurements. + + TABLE A. + + SENSITIVENESS TO LIGHT. + +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23[6]|5 " | 14,000 | 170 | 82.3 " " + " 24[7]|5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129[6]|5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- + +[Footnote 6: Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.] + +[Footnote 7: No. 24 was measured with a bridge multiplier of 6 to 1.] + +Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not. + +_Mode of measuring cells_.--So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently. + +The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison. + +2. _The kind of battery employed_ has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the _resistance_ +of a cell, but it is not clear how or why it should affect the +_sensitiveness of selenium to light_. + +"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?" + +One year ago I made the foregoing suggestion in a paper on _A New Form of +Selenium Cell_, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells. + +3. _The two surfaces of the selenium act differently toward currents_ +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results. + + TABLE B. + + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. + +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- + +The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark. + +4. _Sensitiveness to change of battery power_.--My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified-- + +(a) By changing the potential or electromotive force of the current +through the cell. + +(b) By changing the "quantity" of the battery or current. + +(c) By putting more or less resistance in the circuit. + +(d) By dividing the current, by one or more branch circuits or shunts +around the cell. + +(e) By varying the resistance in any or all of said circuits. + +A cell whose resistance becomes greater as the battery power becomes +greater, and _vice versa_, I call an "L B cell" signifying _Like the +Battery power_. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and _vice +versa_, being _Unlike the Battery power_, or current strength. + +These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change. + +The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms. + + TABLE C. + + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123[8] | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- + +[Footnote 8: This measurement was obtained with 8 elements.] + +The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark. + +5. _Dual state of selenium_.--My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable. + +In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another. + +The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed? + +6. _Radio-electric current generators_.--My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means. + +The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted. + +I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required. + +7. _Singing and speaking cells_.--When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current--and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit. + +My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation. + +GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS. + +From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells." + +The property of sensitiveness to light is independent of the power to +generate current by exposure to light--the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat. + +The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light--their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them. + +The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light. + +_Constancy of the resistance_.--A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms--sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant. + +As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness. + +_Practical applications_.--There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale. + +The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my + +_Photometer_.--The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights--the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light. + +This arrangement leaves untouched the old difficulty in photometry, that +arising from the different _colors_ of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration. + +_Photo-electric regulator_.--My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small. + +In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries. + + * * * * * + + + + +ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH. + + +Messrs. Muethel & Luetche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on. + +The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures. + +The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever. + +[Illustration: FIGS. 1 AND 2.] + +The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60 deg. and 80 deg.. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone. + +When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.--_La Lumiere +Electrique._ + + * * * * * + + + + +NAGLO BROTHERS' TELEPHONE SYSTEM. + + +We borrow from the _Elektrotechnische Zeitung_ the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f_{2}. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f_{1}. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle. + +[Illustration: FIG. 1.] + +Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve. + +This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f_{2} p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling. + +[Illustration: FIGS. 2 AND 3.] + +Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.--_La Lumiere Electrique_. + + * * * * * + + + + +THE GERARD ELECTRIC LAMP. + + +In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage. + +This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp: + + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 + +[Illustration: GERARD'S INCANDESCENT LAMP.] + +It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example--this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps. + +The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature. + +The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.--_Le Genie +Civil_. + + * * * * * + + + + +A NEW REFLECTING GALVANOMETER. + + +Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106 deg. with each other, so that the planes containing the axes of the +bobbins make an angle of about 74 deg.. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated. + +[Illustration: FIG. 1. GRAY'S GALVANOMETER.] + +The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections. + +In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite. + +[Illustration: FIG. 2.] + +The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread. + +The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T', T squared, and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite. + +Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation. + +In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10^{4} to 10^{5} megohms could be +measured by the use of a pile of 120 daniells. + +The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier. + +The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one. + +We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane. + +Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.--_La Lumiere Electrique_. + + * * * * * + + + + +HISTOLOGICAL METHODS. + + +A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required. + +Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly. + +Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol. + +The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol. + +_Section cutting_ machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument. + +A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal. + +When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed. + +With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose. + +[Illustration: FIG. 1.] + +_To out a section by hand_, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush. + +When the object is too small to hold, it is usually _embedded_ in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it. + +Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive. + +Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues. + +Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes. + +Much practice will be required before dexterity is attained. + +_Methods of preserving the tissues_.--All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote. + +The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium. + +The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off. + +_Preservative media_.--Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150 deg.; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine. + +Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased. + +Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained. + +Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts. + +When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement. + +_Preparation for mounting the different tissues_.--To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine. + +Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting. + +The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach. + +The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly. + +The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution. + +Every slide should be of uniform size, and labeled. The usual size is 3x1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required. + + * * * * * + + + + +LIFE HISTORY OF A NEW SEPTIC ORGANISM. + + +At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice +versa_, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form--extending over four years--he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of _Bacterium termo_, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms--one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90 deg. to 95 deg. F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements. + +The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146 deg. F., the highest point endured +by the germs was 190 deg. F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the _modus operandi_ was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law. + + * * * * * + + + + +WINTER AND THE INSECTS. + + +For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellae, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick. + +[Illustration: GREEN WOODPECKER SEARCHING FOR INSECTS.] + +The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line--this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil. + +I now come to the effects of this severe cold upon the insects. + +The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellae, in view of the +previous rarity of the individuals belonging to this family. + +We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvae, pass this season upon the earth +enveloped in a silken envelope, or, like the larvae of the Noctuellae, +between dead leaves or upon the ground itself. + +On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvae and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvae of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera. + +It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvae. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulae are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvae and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans--the wood lice. + +During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvae and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvae are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared. + +In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvae feed and hibernate in the open air a few species of +Noctuellae, whose larvae live buried in the earth, are always abundant. The +country is relatively rich in spices of _Tortrix_, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.--_C.G. Barret, in Science et Nature_. + + * * * * * + + + + +SILK WORM EGGS. + + +Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called _flacherie_, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs: + +[Illustration] + +For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennae, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths. + +There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3x6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room. + +The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day. + +When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered. + + * * * * * + + +Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine. + + * * * * * + +[NATURE.] + + + + +DETERMINING THE MEAN DENSITY OF THE EARTH. + + +In _Nature_ for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the _Nature_ (Jan. 15. p. 260) report of the +_Proceedings_ of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method. + +Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings. + +A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G. + +[Illustration] + +In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance. + +The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary. + +ARTHUR KONIG. + +FRANZ RICHARZ. + +Berlin, Physical Institute of the University, March 15. + + * * * * * + + + + +PHYSICS WITHOUT APPARATUS. + + +_The Porosity and Permeability of Bodies._--Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are _impermeable_, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so _penetrating_. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action. + +[Illustration: Fig. 1.--EXPERIMENT UPON THE PERMEABILITY OF BODIES.] + +_A Hot Air Balloon_.--Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.--_La Nature_. + +[Illustration: Fig. 2.--PRINCIPLE OF THE HOT AIR BALLOON.] + + * * * * * + + + + +THE CASINO AT MONTE CARLO. + + +The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea. + +[Illustration: THE CASINO AT MONTE CARLO.] + +Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces. + +But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player. + +It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined. + + * * * * * + + + + +ON AN EXPRESS ENGINE. + + +It is a somewhat unpromising morning--the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance. + +So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead--the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed--it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades--for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart--where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.--_Saturday Review_. + + * * * * * + + +The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process. + + * * * * * + + + + +ERYTHROXYLON. + +[Footnote: From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.] + + +COCA. + +The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics. + +The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied. + +Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago. + +The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in _The Lancet_ of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body." + +Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages. + +There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.[9] + +[Footnote 9: An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.] + +The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle--namely, caffeine--could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons. + +In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by. + +An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence. + +Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him. + +The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect. + +Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 21/2 grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning. + +This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken. + +The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 21/2 drachms did give a +definite effect, and a subsequent dose of 21/2 fluid drachms of a well made +fluid extract of coca gave about the same effect as 21/2 grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine. + +Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained. + +The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the _American Journal of +Pharmacy_, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows: + +Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent. + +Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory. + +Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid. + +From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process. + +Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle. + + * * * * * + + + + +THE MELLOCO. + + +ULLUCUS TUBEROSA.--Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were. + +[Illustration: MELLOCO TUBERS.] + +We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the _Gardeners' Chronicle_ for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49 deg.." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50 deg. in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements. + +Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers--such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the _Gardeners' Chronicle_ for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.--_W. 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Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..55e3e3e --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #12490 (https://www.gutenberg.org/ebooks/12490) diff --git a/old/12490-8.txt b/old/12490-8.txt new file mode 100644 index 0000000..fe12baa --- /dev/null +++ b/old/12490-8.txt @@ -0,0 +1,4400 @@ +The Project Gutenberg EBook of Scientific American Supplement, No. 492, +June 6, 1885, by Various + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 492, June 6, 1885 + +Author: Various + +Release Date: June 2, 2004 [EBook #12490] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 492 + + + + +NEW YORK, JUNE 6, 1885. + +Scientific American Supplement. Vol. XIX, No. 492. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + + * * * * * + + +TABLE OF CONTENTS. + +I. ENGINEERING AND MECHANICS.--The New Spanish Artillery.--2 + engravings. + + Qualitative Tests for Steel Rails.--By L. TETMAJER. + + A New Form of Small Bessemer Plant.--By A. TRAPPEN. + + Triple Compound Engines.--A paper read by A.E. SEATON + before the Institution of Naval Architects. + + Early History of the Steam Jack. + + Bridge over the River Adige, at Verona.--13 figures. + + Pumping Machinery.--Mine pumps.--Direct acting steam pumps. + By E.D. LEAVITT. + + Improved Gun Pressure Gauge.--2 figures. + + Measuring the Thickness of Boiler Plates. + + On an Express Engine. + + +II. TECHNOLOGY.--Improved Plaiting Machine.--With engraving. + + Self-acting Shuttle Guard.--1 figure. + + Ruler and Triangle for Hatching. + + The Distillation of Sea Water.--1 figure. + + Aids to Correct Exposure on Photographic Plates.--An + interesting paper by W. GOODMAN. + + Isochromatic Photography.--By FRED. E. IVES.--2 figures. + + Distortion from Expansion of the Paper in Photography. + + +III. ELECTRICITY, ETC.--On the Fritts Selenium Cells and + Batteries.--A paper read before the American Association + by C.E. FRITTS. + + Electricity Applied to the Manufacture of Varnish.--2 figures. + + Naglo Brothers' Telephone System.--3 figures. + + The Gerard Electric Lamp.--1 figure. + + A New Reflecting Galvanometer.--3 figures. + + +IV. ART AND ARCHITECTURE.--Groups of Statuary for the Pediment + of the House of Parliament in Vienna.--2 engravings. + + The Casino at Monte Carlo.--An engraving. + + +V. PHYSICS.--Determining the Density of the Earth.--1 figure. + + Physics without Apparatus.--The Porosity and Permeability of + Bodies.--A Hot Air Balloon.--2 engravings. + + +VI. NATURAL HISTORY.--Winter and the Insects.--An engraving. + + Silk Worm Eggs.--With engraving. + + +VII. HORTICULTURE.--The Melleco.--Ullucus tuberosa.--With + engraving. + + +VIII. PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section + cutting machines.--Methods of preserving the + tissues.--Preservative media.--Preparation for mounting + tissues.--1 figure. + + Life History of a New Septic Organism. + + Erythroxylon Coca as a Therapeutic Agent.--By Dr. E.R. SQUIBB. + + * * * * * + + + + +NEW SPANISH ARTILLERY. + + +The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +We give engravings from photographs, as presented in _La Illustracion +Española_. These guns are breech loaders, of steel, 30½ centimeters +caliber, or 12 inches, 49 tons weight. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness. + + * * * * * + + + + +QUALITATIVE TESTS FOR STEEL RAILS. + +By Mr. L. TETMAJER. + + +This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice. + +The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same. + +The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensücherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.--_Stahl und Eisen_, vol. iv., page 608; through +_Proc. Inst. Civ. Eng_. + + * * * * * + + + + +A NEW FORM OF SMALL BESSEMER PLANT. + +By Mr. A. TRAPPEN. + + +The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift. + +The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure. + +The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at £2,050 +to £2,100; and that of the steam boiler, £325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.--_Stahl und +Eisen_, vol. iv., page 524; through _Proc. Inst. Civ. Eng_. + + * * * * * + + + + +TRIPLE COMPOUND ENGINES. + +[Footnote: Paper read before the Institution of Naval Architects, March +27, 1885.] + +By Mr. A.E. SEATON. + + +My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small. + +The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows: + + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 + +And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment. + +After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent. + +In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day. + +The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure. + +So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 20½ inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear. + +I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +½ knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other. + +We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 11½ inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen. + +I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands. + + * * * * * + + + + +EARLY HISTORY OF THE STEAM JACK. + +_To the Editor of the Scientific American:_ + + +A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack." + +Says Mr. J.G. Briggs, in the _American Engineer:_ "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.--a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country--if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment _patent_, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the _Hub_, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston. + +Trusting I have not wearied you, I am, + +ANNA M. BAILEY. + +Bleak House, Lynn, Mass., May 12. + + +COPY OF PATENT. + +_United States_. + +To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. Go. WASHINGTON. + +By the President, + +TH. JEFFERSON. + + +CITY OF PHILADELPHIA, February 23, 1792. + +I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act. + +EDM. RANDOLPH, + +_Attorney-General of the U.S._ + +[SEAL.] + + * * * * * + + + + +BRIDGE AT VERONA. + + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge: + + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 9¾ +Width of bridge 37 4¾ +Depth of arched girders 4 7 + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 _l._; the abutments cost 3,600_l._, +making the total outlay on the structure 12,000_l_. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.--_Engineering_. + + * * * * * + + + + +PUMPING MACHINERY. + +[Footnote: A paper read at the Montreal Meeting of the British +Association.] + +By E.D. LEAVITT, JR., Cambridgeport, Mass. + +MINE PUMPING MACHINERY. + + +One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine. + +At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia Water Works; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines. + +In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well. + +The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States. + +A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned. + +Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet. + +The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps. + +The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 22½ feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine. + +In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 4½ inches thickness of metal. The pump rock shaft +is 39 feet 4½ inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine. + +The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft. + +The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to ½ inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute. + +The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 17½ inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same. + +The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections. + +The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links. + +The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 5¼ inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity. + +The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory. + + +DIRECT ACTING STEAM PUMPS. + +This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined. + +The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish. + + * * * * * + + + + +IMPROVED GUN PRESSURE GAUGE. + + +The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor. + +[Illustration: IMPROVED GUN PRESSURE GAUGE.] + +Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb. + +It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with. + +The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds. + +The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice. + +This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder. + + * * * * * + + + + +IMPROVED PLAITING MACHINE. + + +The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length. + +[Illustration: IMPROVED PLAITING MACHINE.] + +To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner: + +Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G¹ G¹. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires. + +It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.--_Tex. Manfr._ + + * * * * * + + + + +SELF-ACTING SHUTTLE GUARD. + + +[Illustration: SELF-ACTING SHUTTLE GUARD.] + +The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers. + + * * * * * + + + + +RULER AND TRIANGLE FOR HATCHING. + + +The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45°, but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former. + +[Illustration: RULER AND TRIANGLE FOR HATCHING.] + +The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.--_Chronique Industrielle_. + + * * * * * + + + + +THE DISTILLATION OF SEA WATER. + + +The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service. + +Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process. + +In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried. + +Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 4½ cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes--in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser. + +[Illustration] + +Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order. + +As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +2¼ gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance. + +Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is _said_ are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.--_The Engineer_. + + * * * * * + + + + +AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES. + +[Footnote: We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.] + + +With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative. + + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ + +The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum. + +The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done. + +Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed. + +The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both. + +The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens. + +The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size. + +First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch. + +Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 7½ in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two. + +We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table. + +We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium _nitrite_ (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough. + +However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass. + +Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done--kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer. + +When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right. + +Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table. + +You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only. + +On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures. + +I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous. + +The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you _may_ make a negative of an overexposed plate, but never +of an underexposed one. + + * * * * * + + + + +ISOCHROMATIC PHOTOGRAPHY. + +[Footnote: Read at the stated meeting of the Franklin Institute, March +18, 1885.] + +By FRED. E. IVES. + + +It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography. + +Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process. + +In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, _why_ it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives--blue, yellow, and red--would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow. + +Having succeeded perfectly in my undertakings, I published my discovery +in 1879,[1] explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.[2] + +[Footnote 1: _Philadelphia Photographer_, December, 1879, p. 365.] + +[Footnote 2: I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the _Photo. News_, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +_Photo. News_, Nov. 1883, p. 747.] + +So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,[3] +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness. + +[Footnote 3: _Photo. News_, London, September 5, 1884, p. 566, and _Year +Book of Photography_ for 1885, p. 111.] + +My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.[4] A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure. + +[Footnote 4: I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from _fresh_ +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.] + +My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement. + +The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer. + +[Illustration: IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.] + +In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank. + +I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them. + +To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered. + +Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness. + +I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination. + +Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but _comparatively insensitive to +red_, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process. + + * * * * * + + + + +DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY. + + +The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper. + +When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears. + +If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness--owing to +this particular distortion--of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied. + +Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby. + +To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight--perhaps imperceptible--compared with that existing +when the prints are mounted wet. I may mention, _en passant_, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system. + +The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion. + +For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there. + +Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion. + +A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass. + +Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled. + +The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.--_W.E. +Debenham, in Br. Jour. of Photography_. + + * * * * * + + + + +MEASURING THE THICKNESS OF BOILER PLATES. + + +An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy. + + * * * * * + + + + +GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA. + + +The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--SCIENCE +AND LITERATURE. (GROUP TO THE LEFT.)] + +The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government. + +Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows. + +A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry. + +Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--INDUSTRY +AND COMMERCE. (GROUP TO THE RIGHT.)] + +The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.--_Illustrirte Zeitung_. + + * * * * * + + + + +ON THE FRITTS SELENIUM CELLS AND BATTERIES. + +[Footnote: Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.] + +By C.E. FRITTS, 42 Nassau St., New York, N.Y. + + +In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface. + +My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure. + +During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a _transparent conductor of electricity_, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.[5] My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired. + +[Footnote 5: The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.] + +By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following: + +1. _Their sensitiveness to light_ is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells. + +It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 _per cent_. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained _less than 3/10 of 1 per cent_. of the original +resistance of the selenium in dark. + +In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act +through the gold, in conjunction, their forces are united; and, as every +atom of the selenium is affected by the light, owing to the extreme +thinness of the plate, we have the full effect shown in the measurements. + + TABLE A. + + SENSITIVENESS TO LIGHT. + +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23[6]|5 " | 14,000 | 170 | 82.3 " " + " 24[7]|5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129[6]|5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- + +[Footnote 6: Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.] + +[Footnote 7: No. 24 was measured with a bridge multiplier of 6 to 1.] + +Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not. + +_Mode of measuring cells_.--So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently. + +The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison. + +2. _The kind of battery employed_ has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the _resistance_ +of a cell, but it is not clear how or why it should affect the +_sensitiveness of selenium to light_. + +"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?" + +One year ago I made the foregoing suggestion in a paper on _A New Form of +Selenium Cell_, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells. + +3. _The two surfaces of the selenium act differently toward currents_ +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results. + + TABLE B. + + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. + +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- + +The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark. + +4. _Sensitiveness to change of battery power_.--My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified-- + +(a) By changing the potential or electromotive force of the current +through the cell. + +(b) By changing the "quantity" of the battery or current. + +(c) By putting more or less resistance in the circuit. + +(d) By dividing the current, by one or more branch circuits or shunts +around the cell. + +(e) By varying the resistance in any or all of said circuits. + +A cell whose resistance becomes greater as the battery power becomes +greater, and _vice versa_, I call an "L B cell" signifying _Like the +Battery power_. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and _vice +versa_, being _Unlike the Battery power_, or current strength. + +These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change. + +The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms. + + TABLE C. + + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123[8] | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- + +[Footnote 8: This measurement was obtained with 8 elements.] + +The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark. + +5. _Dual state of selenium_.--My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable. + +In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another. + +The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed? + +6. _Radio-electric current generators_.--My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means. + +The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted. + +I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required. + +7. _Singing and speaking cells_.--When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current--and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit. + +My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation. + +GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS. + +From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells." + +The property of sensitiveness to light is independent of the power to +generate current by exposure to light--the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat. + +The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light--their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them. + +The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light. + +_Constancy of the resistance_.--A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms--sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant. + +As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness. + +_Practical applications_.--There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale. + +The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my + +_Photometer_.--The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights--the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light. + +This arrangement leaves untouched the old difficulty in photometry, that +arising from the different _colors_ of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration. + +_Photo-electric regulator_.--My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small. + +In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries. + + * * * * * + + + + +ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH. + + +Messrs. Müthel & Lütche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on. + +The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures. + +The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever. + +[Illustration: FIGS. 1 AND 2.] + +The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60° and 80°. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone. + +When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.--_La Lumiere +Electrique._ + + * * * * * + + + + +NAGLO BROTHERS' TELEPHONE SYSTEM. + + +We borrow from the _Elektrotechnische Zeitung_ the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f_{2}. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f_{1}. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle. + +[Illustration: FIG. 1.] + +Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve. + +This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f_{2} p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling. + +[Illustration: FIGS. 2 AND 3.] + +Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.--_La Lumiere Electrique_. + + * * * * * + + + + +THE GERARD ELECTRIC LAMP. + + +In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage. + +This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp: + + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 + +[Illustration: GERARD'S INCANDESCENT LAMP.] + +It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example--this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps. + +The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature. + +The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.--_Le Genie +Civil_. + + * * * * * + + + + +A NEW REFLECTING GALVANOMETER. + + +Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106° with each other, so that the planes containing the axes of the +bobbins make an angle of about 74°. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated. + +[Illustration: FIG. 1. GRAY'S GALVANOMETER.] + +The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections. + +In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite. + +[Illustration: FIG. 2.] + +The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread. + +The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T¹, T², and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite. + +Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation. + +In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10^{4} to 10^{5} megohms could be +measured by the use of a pile of 120 daniells. + +The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier. + +The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one. + +We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane. + +Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.--_La Lumiere Electrique_. + + * * * * * + + + + +HISTOLOGICAL METHODS. + + +A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required. + +Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly. + +Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol. + +The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol. + +_Section cutting_ machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument. + +A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal. + +When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed. + +With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose. + +[Illustration: FIG. 1.] + +_To out a section by hand_, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush. + +When the object is too small to hold, it is usually _embedded_ in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it. + +Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive. + +Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues. + +Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes. + +Much practice will be required before dexterity is attained. + +_Methods of preserving the tissues_.--All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote. + +The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium. + +The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off. + +_Preservative media_.--Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150°; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine. + +Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased. + +Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained. + +Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts. + +When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement. + +_Preparation for mounting the different tissues_.--To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine. + +Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting. + +The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach. + +The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly. + +The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution. + +Every slide should be of uniform size, and labeled. The usual size is 3×1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required. + + * * * * * + + + + +LIFE HISTORY OF A NEW SEPTIC ORGANISM. + + +At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice +versa_, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form--extending over four years--he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of _Bacterium termo_, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms--one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90° to 95° F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements. + +The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146° F., the highest point endured +by the germs was 190° F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the _modus operandi_ was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law. + + * * * * * + + + + +WINTER AND THE INSECTS. + + +For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellae, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick. + +[Illustration: GREEN WOODPECKER SEARCHING FOR INSECTS.] + +The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line--this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil. + +I now come to the effects of this severe cold upon the insects. + +The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellae, in view of the +previous rarity of the individuals belonging to this family. + +We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvae, pass this season upon the earth +enveloped in a silken envelope, or, like the larvae of the Noctuellae, +between dead leaves or upon the ground itself. + +On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvae and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvae of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera. + +It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvae. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulae are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvae and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans--the wood lice. + +During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvae and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvae are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared. + +In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvae feed and hibernate in the open air a few species of +Noctuellae, whose larvae live buried in the earth, are always abundant. The +country is relatively rich in spices of _Tortrix_, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.--_C.G. Barret, in Science et Nature_. + + * * * * * + + + + +SILK WORM EGGS. + + +Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called _flacherie_, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs: + +[Illustration] + +For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennae, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths. + +There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3×6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room. + +The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day. + +When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered. + + * * * * * + + +Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine. + + * * * * * + +[NATURE.] + + + + +DETERMINING THE MEAN DENSITY OF THE EARTH. + + +In _Nature_ for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the _Nature_ (Jan. 15. p. 260) report of the +_Proceedings_ of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method. + +Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings. + +A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G. + +[Illustration] + +In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance. + +The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary. + +ARTHUR KONIG. + +FRANZ RICHARZ. + +Berlin, Physical Institute of the University, March 15. + + * * * * * + + + + +PHYSICS WITHOUT APPARATUS. + + +_The Porosity and Permeability of Bodies._--Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are _impermeable_, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so _penetrating_. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action. + +[Illustration: Fig. 1.--EXPERIMENT UPON THE PERMEABILITY OF BODIES.] + +_A Hot Air Balloon_.--Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.--_La Nature_. + +[Illustration: Fig. 2.--PRINCIPLE OF THE HOT AIR BALLOON.] + + * * * * * + + + + +THE CASINO AT MONTE CARLO. + + +The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea. + +[Illustration: THE CASINO AT MONTE CARLO.] + +Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces. + +But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player. + +It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined. + + * * * * * + + + + +ON AN EXPRESS ENGINE. + + +It is a somewhat unpromising morning--the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance. + +So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead--the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed--it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades--for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart--where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.--_Saturday Review_. + + * * * * * + + +The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process. + + * * * * * + + + + +ERYTHROXYLON. + +[Footnote: From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.] + + +COCA. + +The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics. + +The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied. + +Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago. + +The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in _The Lancet_ of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body." + +Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages. + +There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.[9] + +[Footnote 9: An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.] + +The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle--namely, caffeine--could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons. + +In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by. + +An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence. + +Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him. + +The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect. + +Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 2½ grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning. + +This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken. + +The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 2½ drachms did give a +definite effect, and a subsequent dose of 2½ fluid drachms of a well made +fluid extract of coca gave about the same effect as 2½ grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine. + +Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained. + +The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the _American Journal of +Pharmacy_, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows: + +Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent. + +Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory. + +Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid. + +From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process. + +Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle. + + * * * * * + + + + +THE MELLOCO. + + +ULLUCUS TUBEROSA.--Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were. + +[Illustration: MELLOCO TUBERS.] + +We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the _Gardeners' Chronicle_ for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49°." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50° in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements. + +Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers--such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the _Gardeners' Chronicle_ for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.--_W. Waston, Kew; +The Gardeners' Chronicle_. + + * * * * * + + +A catalogue, containing brief notices of many important scientific papers +heretofore published in the SUPPLEMENT, may be had gratis at this office. + + + * * * * * + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + +PUBLISHED WEEKLY. + +TERMS OF SUBSCRIPTION, $5 A YEAR. + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of THE SUPPLEMENT, from the commencement, January 1, +1876, can be had. Price, 10 cents each. + +All the back volumes of THE SUPPLEMENT can likewise be supplied. Two +volumes are issued yearly. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 492, June 6, 1885 + +Author: Various + +Release Date: June 2, 2004 [EBook #12490] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team + + + + + +</pre> + +<p class="ctr"><a href="./illustrations/1a.png"><img src="./illustrations/1a_th.jpg" alt="TITLE"></a></p> + +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 492</h1> +<h2>NEW YORK, JUNE 6, 1885</h2> +<h4>Scientific American Supplement. Vol. XIX, No. 492.</h4> +<h4>Scientific American established 1845</h4> +<h4>Scientific American Supplement, $5 a year.</h4> +<h4>Scientific American and Supplement, $7 a year.</h4> +<hr> +<table summary="Contents" border="0" cellspacing="5"> +<tr> +<th colspan="2">TABLE OF CONTENTS.</th> +</tr> +<tr> +<td valign="top">I.</td> +<td><a href="#1"> +ENGINEERING AND MECHANICS.—The New Spanish Artillery.—2 + engravings. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#2"> +Qualitative Tests for Steel Rails.—By L. TETMAJER. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#3"> +A New Form of Small Bessemer Plant.—By A. TRAPPEN. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#4"> +Triple Compound Engines.—A paper read by A.E. SEATON + before the Institution of Naval Architects. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#5"> +Early History of the Steam Jack. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#6"> +Bridge over the River Adige, at Verona.—13 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#7"> +Pumping Machinery.—Mine pumps.—Direct acting steam pumps. + By E.D. LEAVITT. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#8"> + Improved Gun Pressure Gauge.—2 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#9"> +Measuring the Thickness of Boiler Plates. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#32"> + On an Express Engine. +</a></td> +</tr> +<tr> +<td valign="top">II.</td> +<td><a href="#10"> +TECHNOLOGY.—Improved Plaiting Machine.—With engraving. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#11"> + Self-acting Shuttle Guard.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#12"> +Ruler and Triangle for Hatching. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#13"> +The Distillation of Sea Water.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#14"> +Aids to Correct Exposure on Photographic Plates.—An + interesting paper by W. GOODMAN. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#15"> +Isochromatic Photography.—By FRED. E. IVES.—2 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#16"> +Distortion from Expansion of the Paper in Photography. +</a></td> +</tr> +<tr> +<td valign="top">III.</td> +<td><a href="#17"> +ELECTRICITY, ETC.—On the Fritts Selenium Cells and + Batteries.—A paper read before the American Association + by C.E. FRITTS. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#18"> +Electricity Applied to the Manufacture of Varnish.—2 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#19"> +Naglo Brothers' Telephone System.—3 figures. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#20"> +The Gerard Electric Lamp.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#21"> +A New Reflecting Galvanometer.—3 figures. +</a></td> +</tr> +<tr> +<td valign="top">IV.</td> +<td><a href="#22"> +ART AND ARCHITECTURE.—Groups of Statuary for the Pediment + of the House of Parliament in Vienna.—2 engravings. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#23"> +The Casino at Monte Carlo.—An engraving. +</a></td> +</tr> +<tr> +<td valign="top">V.</td> +<td><a href="#24"> +PHYSICS.—Determining the Density of the Earth.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#25"> +Physics without Apparatus.—The Porosity and Permeability of + Bodies.—A Hot Air Balloon.—2 engravings. +</a></td> +</tr> +<tr> +<td valign="top">VI.</td> +<td><a href="#26"> +NATURAL HISTORY.—Winter and the Insects.—An engraving. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#27"> +Silk Worm Eggs.—With engraving. +</a></td> +</tr> +<tr> +<td valign="top">VII.</td> +<td><a href="#28"> +HORTICULTURE.—The Melleco.—Ullucus tuberosa.—With + engraving. +</a></td> +</tr> +<tr> +<td valign="top">VIII.</td> +<td><a href="#29"> +PHYSIOLOGY, MEDICINE, ETC.—Histological Methods.—Section + cutting machines.—Methods of preserving the + tissues.—Preservative media.—Preparation for mounting + tissues.—1 figure. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#30"> + Life History of a New Septic Organism. +</a></td> +</tr> +<tr> +<td></td> +<td><a href="#31"> +Erythroxylon Coca as a Therapeutic Agent.—By Dr. E.R. SQUIBB. +</a></td> +</tr> +</table> + +<hr> + +<p><a name="1"></a></p> +<h2>NEW SPANISH ARTILLERY.</h2> + +<p>The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon.</p> + +<p class="ctr"><a href="./illustrations/1b.png"><img src="./illustrations/1b_th.jpg" alt=" NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS."></a></p><p class="ctr"> NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.</p> + +<p>We give engravings from photographs, as presented in <i>La Illustracion +Española</i>. These guns are breech loaders, of steel, 30½ centimeters +caliber, or 12 inches, 49 tons weight.</p> + +<p class="ctr"><a href="./illustrations/1c.png"><img src="./illustrations/1c_th.jpg" alt=" NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS."></a></p><p class="ctr"> NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.</p> + +<p>One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness.</p> + +<hr> + +<p><a name="2"></a></p> +<h2>QUALITATIVE TESTS FOR STEEL RAILS.</h2> + +<h3>By Mr. L. TETMAJER.</h3> + +<p>This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice.</p> + +<p>The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same.</p> + +<p>The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensücherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.—<i>Stahl und Eisen</i>, vol. iv., page 608; through +<i>Proc. Inst. Civ. Eng</i>.</p> + +<hr> + +<p><a name="3"></a></p> +<h2>A NEW FORM OF SMALL BESSEMER PLANT.</h2> + +<h3>By Mr. A. TRAPPEN.</h3> + +<p>The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift.</p> + +<p>The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure.</p> + +<p>The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at £2,050 +to £2,100; and that of the steam boiler, £325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.—<i>Stahl und +Eisen</i>, vol. iv., page 524; through <i>Proc. Inst. Civ. Eng</i>.</p> + +<hr> + +<p><a name="4"></a></p> +<h2>TRIPLE COMPOUND ENGINES.<a name="FNanchor1"></a><a href="#Footnote_1"><sup>[1]</sup></a></h2> + +<h3>By Mr. A.E. SEATON.</h3> + +<p>My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small.</p> + +<p>The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows:</p> + +<pre> + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 +</pre> + +<p>And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment.</p> + +<p>After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent.</p> + +<p>In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day.</p> + +<p>The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure.</p> + +<p>So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 20½ inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear.</p> + +<p>I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +½ knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other.</p> + +<p>We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 11½ inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen.</p> + +<p>I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands.</p> + +<a name="Footnote_1"></a><a href="#FNanchor1">[1]</a><div class=note>Paper read before the Institution of Naval Architects, March +27, 1885.</div> + +<hr> + +<p><a name="5"></a></p> +<h2>EARLY HISTORY OF THE STEAM JACK.</h2> + +<p><i>To the Editor of the Scientific American:</i></p> + +<p>A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack."</p> + +<p>Says Mr. J.G. Briggs, in the <i>American Engineer:</i> "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.—a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country—if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment <i>patent</i>, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the <i>Hub</i>, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston.</p> + +<p>Trusting I have not wearied you, I am,</p> + +<p>ANNA M. BAILEY.</p> + +<p>Bleak House, Lynn, Mass., May 12.</p> + +<h3>COPY OF PATENT.</h3> + +<p><i>United States</i>.</p> + +<p>To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. G<sup>o</sup>. WASHINGTON.</p> + +<p>By the President,</p> + +<p>TH. JEFFERSON.</p> + +<p>CITY OF PHILADELPHIA, February 23, 1792.</p> + +<p>I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act.</p> + +<p>EDM. RANDOLPH,</p> + +<p><i>Attorney-General of the U.S.</i></p> + +<p>[SEAL.]</p> + +<hr> + +<p><a name="6"></a></p> +<h2>BRIDGE AT VERONA.</h2> + +<p class="ctr"><a href="./illustrations/3a.png"><img src="./illustrations/3a_th.jpg" alt=" BRIDGE OVER THE RIVER ADIGE, AT VERONA."></a></p><p class="ctr"> BRIDGE OVER THE RIVER ADIGE, AT VERONA.</p> + +<p>The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge:</p> + +<pre> + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 9¾ +Width of bridge 37 4¾ +Depth of arched girders 4 7 +</pre> + +<p>The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 <i>l.</i>; the abutments cost 3,600<i>l.</i>, +making the total outlay on the structure 12,000<I>l</I>. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.—<i>Engineering</i>.</p> + +<p class="ctr"><a href="./illustrations/3b.png"><img src="./illustrations/3b_th.jpg" alt=" BRIDGE OVER THE RIVER ADIGE, AT VERONA."></a></p><p class="ctr"> BRIDGE OVER THE RIVER ADIGE, AT VERONA.</p> + +<hr> + +<p><a name="7"></a></p> +<h2>PUMPING MACHINERY.<a name="FNanchor2"></a><a href="#Footnote_2"><sup>[1]</sup></a></h2> + +<h3>By E.D. LEAVITT, JR., Cambridgeport, Mass.</h3> + +<h3>MINE PUMPING MACHINERY.</h3> + +<p>One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine.</p> + +<p>At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia WaterWorks; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines.</p> + +<p>In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well.</p> + +<p>The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States.</p> + +<p>A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned.</p> + +<p>Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet.</p> + +<p>The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps.</p> + +<p>The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 22½ feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine.</p> + +<p>In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 4½ inches thickness of metal. The pump rock shaft +is 39 feet 4½ inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine.</p> + +<p>The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft.</p> + +<p>The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to ½ inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute.</p> + +<p>The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 17½ inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same.</p> + +<p>The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections.</p> + +<p>The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links.</p> + +<p>The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 5¼ inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity.</p> + +<p>The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory.</p> + +<h3>DIRECT ACTING STEAM PUMPS.</h3> + +<p>This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined.</p> + +<p>The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish.</p> + +<a name="Footnote_2"></a><a href="#FNanchor2">[1]</a><div class=note>A paper read at the Montreal Meeting of the British +Association.</div> + +<hr> + +<p><a name="8"></a></p> +<h2>IMPROVED GUN PRESSURE GAUGE.</h2> + +<p>The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor.</p> + +<p class="ctr"><a href="./illustrations/4a.png"><img src="./illustrations/4a_th.jpg" alt=" IMPROVED GUN PRESSURE GAUGE."></a></p><p class="ctr"> IMPROVED GUN PRESSURE GAUGE.</p> + +<p>Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb.</p> + +<p>It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with.</p> + +<p>The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds.</p> + +<p>The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice.</p> + +<p>This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder.</p> + +<hr> + +<p><a name="10"></a></p> +<h2>IMPROVED PLAITING MACHINE.</h2> + +<p>The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length.</p> + +<p class="ctr"><a href="./illustrations/5a.png"><img src="./illustrations/5a_th.jpg" alt=" IMPROVED PLAITING MACHINE."></a></p><p class="ctr"> IMPROVED PLAITING MACHINE.</p> + +<p>To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner:</p> + +<p>Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G<sup>1</sup> G<sup>1</sup>. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires.</p> + +<p>It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.—<i>Tex. Manfr</i>.</p> + +<hr> + +<p><a name="11"></a></p> +<h2>SELF-ACTING SHUTTLE GUARD.</h2> + +<p class="ctr"><a href="./illustrations/5b.png"><img src="./illustrations/5b_th.jpg" alt=" SELF-ACTING SHUTTLE GUARD."></a></p><p class="ctr"> SELF-ACTING SHUTTLE GUARD.</p> + +<p>The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers.</p> + +<hr> + +<p><a name="12"></a></p> +<h2>RULER AND TRIANGLE FOR HATCHING.</h2> + +<p>The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45°, but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former.</p> + +<p class="ctr"><a href="./illustrations/5c.png"><img src="./illustrations/5c_th.jpg" alt=" RULER AND TRIANGLE FOR HATCHING."></a></p><p class="ctr"> RULER AND TRIANGLE FOR HATCHING.</p> + +<p>The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.—<i>Chronique Industrielle</i>.</p> + +<hr> + +<p><a name="13"></a></p> +<h2>THE DISTILLATION OF SEA WATER.</h2> + +<p>The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service.</p> + +<p>Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process.</p> + +<p>In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried.</p> + +<p>Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 4½ cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes—in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser.</p> + +<p class="ctr"><a href="./illustrations/6a.png"><img src="./illustrations/6a_th.jpg" alt=""></a></p> + +<p>Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order.</p> + +<p>As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +2¼ gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance.</p> + +<p>Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is <i>said</i> are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.—<i>The Engineer</i>.</p> + +<hr> + +<p><a name="14"></a></p> +<h2>AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES.<a name="FNanchor3"></a><a href="#Footnote_3"><sup>[1]</sup></a></h2> + +<p>With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative.</p> + +<pre> + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +</pre> + +<p>The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum.</p> + +<p>The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done.</p> + +<p>Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed.</p> + +<p>The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both.</p> + +<p>The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens.</p> + +<p>The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size.</p> + +<p>First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch.</p> + +<p>Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 7½ in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two.</p> + +<p>We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table.</p> + +<p>We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium <i>nitrite</i> (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough.</p> + +<p>However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass.</p> + +<p>Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done—kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer.</p> + +<p>When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right.</p> + +<p>Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table.</p> + +<p>You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only.</p> + +<p>On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures.</p> + +<p>I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous.</p> + +<p>The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you <i>may</i> make a negative of an overexposed plate, but never +of an underexposed one.</p> + +<a name="Footnote_3"></a><a href="#FNanchor3">[1]</a><div class=note> We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.</div> + +<hr> + +<p><a name="15"></a></p> +<h2>ISOCHROMATIC PHOTOGRAPHY.<a name="FNanchor4"></a><a href="#Footnote_4"><sup>[1]</sup></a></h2> + +<h3>By FRED. E. IVES.</h3> + +<p>It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography.</p> + +<p>Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process.</p> + +<p>In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, <i>why</i> it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives—blue, yellow, and red—would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow.</p> + +<p>Having succeeded perfectly in my undertakings, I published my discovery +in 1879,<a name="FNanchor5"></a><a href="#Footnote_5"><sup>[2]</sup></a> explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.<a name="FNanchor6"></a><a href="#Footnote_6"><sup>[3]</sup></a></p> + +<p>So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,<a name="FNanchor7"></a><a href="#Footnote_7"><sup>[4]</sup></a> +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness.</p> + +<p>My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.<a name="FNanchor8"></a><a href="#Footnote_8"><sup>[5]</sup></a> A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure.</p> + +<p>My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement.</p> + +<p>The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer.</p> + +<p class="ctr"><a href="./illustrations/7a.png"><img src="./illustrations/7a_th.jpg" alt=" IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY."></a></p><p class="ctr"> IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.</p> + +<p>In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank.</p> + +<p>I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them.</p> + +<p>To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered.</p> + +<p>Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness.</p> + +<p>I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination.</p> + +<p>Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but <i>comparatively insensitive to +red</i>, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process.</p> + +<a name="Footnote_4"></a><a href="#FNanchor4">[1]</a><div class=note>Read at the stated meeting of the Franklin Institute, March +18, 1885.</div> + +<a name="Footnote_5"></a><a href="#FNanchor5">[2]</a><div class=note><i>Philadelphia Photographer</i>, December, 1879, p. 365.</div> + +<a name="Footnote_6"></a><a href="#FNanchor6">[3]</a><div class=note> I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the <i>Photo. News</i>, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +<i>Photo. News</i>, Nov. 1883, p. 747.</div> + +<a name="Footnote_7"></a><a href="#FNanchor7">[4]</a><div class=note><i>Photo. News</i>, London, September 5, 1884, p. 566, and <i>Year +Book of Photography</i> for 1885, p. 111.</div> + +<a name="Footnote_8"></a><a href="#FNanchor8">[5]</a><div class=note>I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from <i>fresh</i> +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.</div> + +<hr> + +<p><a name="16"></a></p> +<h2>DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY.</h2> + +<p>The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper.</p> + +<p>When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears.</p> + +<p>If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness—owing to +this particular distortion—of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied.</p> + +<p>Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby.</p> + +<p>To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight—perhaps imperceptible—compared with that existing +when the prints are mounted wet. I may mention, <i>en passant</i>, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system.</p> + +<p>The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion.</p> + +<p>For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there.</p> + +<p>Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion.</p> + +<p>A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass.</p> + +<p>Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled.</p> + +<p>The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.—<i>W.E. +Debenham, in Br. Jour. of Photography</i>.</p> + +<hr> + +<p><a name="9"></a></p> +<h2>MEASURING THE THICKNESS OF BOILER PLATES.</h2> + +<p>An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy.</p> + +<hr> + +<p><a name="22"></a></p> +<h2>GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA.</h2> + +<p>The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer.</p> + +<p class="ctr"><a href="./illustrations/8a.png"><img src="./illustrations/8a_th.jpg" alt=" STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—SCIENCE AND LITERATURE. (GROUP TO THE LEFT.)"></a></p><p class="ctr"> STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—SCIENCE AND LITERATURE. (GROUP TO THE LEFT.)</p> + +<p>The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government.</p> + +<p>Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows.</p> + +<p>A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry.</p> + +<p>Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce.</p> + +<p class="ctr"><a href="./illustrations/9a.png"><img src="./illustrations/9a_th.jpg" alt=" STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—INDUSTRY AND COMMERCE. (GROUP TO THE RIGHT.)"></a></p><p class="ctr"> STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.—INDUSTRY AND COMMERCE. (GROUP TO THE RIGHT.)</p> + +<p>The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.—<i>Illustrirte Zeitung</i>.</p> + +<hr> + +<p><a name="17"></a></p> +<h2>ON THE FRITTS SELENIUM CELLS AND BATTERIES.<a name="FNanchor9"></a><a href="#Footnote_9"><sup>[1]</sup></a></h2> + +<h3>By C.E. FRITTS, 42 Nassau St., New York, N.Y.</h3> + +<p>In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface.</p> + +<p>My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure.</p> + +<p>During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a <i>transparent conductor of electricity</i>, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.<a name="FNanchor10"></a><a href="#Footnote_10"><sup>[2]</sup></a> My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired.</p> + +<p>By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following:</p> + +<p>1. <i>Their sensitiveness to light</i> is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells.</p> + +<p>It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 <i>per cent</i>. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained <i>less than 3/10 of 1 per cent</i>. of the original +resistance of the selenium in dark.</p> + +<p>In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act through +the gold, in conjunction, their forces are united; and, as every atom of +the selenium is affected by the light, owing to the extreme thinness of +the plate, we have the full effect shown in the measurements.</p> + +<pre> +----------------------------------------------------------------- + TABLE A. + SENSITIVENESS TO LIGHT. +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23<a name="FNanchor11"></a><a href="#Footnote_11">³</a> |5 " | 14,000 | 170 | 82.3 " " + " 24<a name="FNanchor12"></a><a href="#Footnote_12">⁴</a> |5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129<a href="#Footnote_11">³</a> |5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- +</pre> + +<p>Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not.</p> + +<p><i>Mode of measuring cells</i>.—So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently.</p> + +<p>The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison.</p> + +<p>2. <i>The kind of battery employed</i> has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the <i>resistance</i> +of a cell, but it is not clear how or why it should affect the +<i>sensitiveness of selenium to light</i>.</p> + +<p>"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?"</p> + +<p>One year ago I made the foregoing suggestion in a paper on <i>A New Form of +Selenium Cell</i>, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells.</p> + +<p>3. <i>The two surfaces of the selenium act differently toward currents</i> +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results.</p> + +<pre> +------------------------------------------------------------------- + TABLE B. + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- +</pre> + +<p>The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark.</p> + +<p>4. <i>Sensitiveness to change of battery power</i>.—My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified—</p> + +<p>(a) By changing the potential or electromotive force of the current +through the cell.</p> + +<p>(b) By changing the "quantity" of the battery or current.</p> + +<p>(c) By putting more or less resistance in the circuit.</p> + +<p>(d) By dividing the current, by one or more branch circuits or shunts +around the cell.</p> + +<p>(e) By varying the resistance in any or all of said circuits.</p> + +<p>A cell whose resistance becomes greater as the battery power becomes +greater, and <i>vice versa</i>, I call an "L B cell" signifying <i>Like the +Battery power</i>. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and <i>vice +versa</i>, being <i>Unlike the Battery power</i>, or current strength.</p> + +<p>These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change.</p> + +<p>The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms.</p> + +<pre> +--------------------------------------------------------------- + TABLE C. + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123<a name="FNanchor13"></a><a href="#Footnote_13">⁵</a> | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- +</pre> + +<p>The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark.</p> + +<p>5. <i>Dual state of selenium</i>.—My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable.</p> + +<p>In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another.</p> + +<p>The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed?</p> + +<p>6. <i>Radio-electric current generators</i>.—My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means.</p> + +<p>The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted.</p> + +<p>I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required.</p> + +<p>7. <i>Singing and speaking cells</i>.—When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current—and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit.</p> + +<p>My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation.</p> + +<h3>GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS.</h3> + +<p>From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells."</p> + +<p>The property of sensitiveness to light is independent of the power to +generate current by exposure to light—the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat.</p> + +<p>The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light—their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them.</p> + +<p>The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light.</p> + +<p><i>Constancy of the resistance</i>.—A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms—sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant.</p> + +<p>As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness.</p> + +<p><i>Practical applications</i>.—There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale.</p> + +<p>The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my</p> + +<p><i>Photometer</i>.—The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights—the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light.</p> + +<p>This arrangement leaves untouched the old difficulty in photometry, that +arising from the different <i>colors</i> of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration.</p> + +<p><i>Photo-electric regulator</i>.—My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small.</p> + +<p>In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries.</p> + +<a name="Footnote_9"></a><a href="#FNanchor9">[1]</a><div class=note>Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.</div> + +<a name="Footnote_10"></a><a href="#FNanchor10">[2]</a><div class=note>The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.</div> + +<a name="Footnote_11"></a><a href="#FNanchor11">[3]</a><div class=note>Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.</div> + +<a name="Footnote_12"></a><a href="#FNanchor12">[4]</a><div class=note>No. 24 was measured with a bridge multiplier of 6 to 1.</div> + +<a name="Footnote_13"></a><a href="#FNanchor13">[5]</a><div class=note>This measurement was obtained with 8 elements.</div> + +<hr> + +<p><a name="18"></a></p> +<h2>ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH.</h2> + +<p>Messrs. Müthel & Lütche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on.</p> + +<p>The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures.</p> + +<p>The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever.</p> + +<p class="ctr"><a href="./illustrations/11a.png"><img src="./illustrations/11a_th.jpg" alt=" FIGS. 1 AND 2."></a></p><p class="ctr"> FIGS. 1 AND 2.</p> + +<p>The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60° and 80°. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone.</p> + +<p>When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.—<i>La Lumiere +Electrique.</i></p> + +<hr> + +<p><a name="19"></a></p> +<h2>NAGLO BROTHERS' TELEPHONE SYSTEM.</h2> + +<p>We borrow from the <i>Elektrotechnische Zeitung</i> the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f<sub>2</sub>. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f<sub>1</sub>. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle.</p> + +<p class="ctr"><a href="./illustrations/11b.png"><img src="./illustrations/11b_th.jpg" alt=" FIG. 1."></a></p><p class="ctr"> FIG. 1.</p> + +<p>Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve.</p> + +<p>This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f<sub>2</sub> p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling.</p> + +<p class="ctr"><a href="./illustrations/11c.png"><img src="./illustrations/11c_th.jpg" alt=" FIGS. 2 AND 3."></a></p><p class="ctr"> FIGS. 2 AND 3.</p> + +<p>Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.—<i>La Lumiere Electrique</i>.</p> + +<hr> + +<p><a name="20"></a></p> +<h2>THE GERARD ELECTRIC LAMP.</h2> + +<p>In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage.</p> + +<p>This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp:</p> + +<pre> + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 +</pre> + +<p>It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example—this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps.</p> + +<p class="ctr"><a href="./illustrations/11d.png"><img src="./illustrations/11d_th.jpg" alt=" GERARD'S INCANDESCENT LAMP."></a></p><p class="ctr"> GERARD'S INCANDESCENT LAMP.</p> + +<p>The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature.</p> + +<p>The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.—<i>Le Genie +Civil</i>.</p> + +<hr> + +<p><a name="21"></a></p> +<h2>A NEW REFLECTING GALVANOMETER.</h2> + +<p>Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106° with each other, so that the planes containing the axes of the +bobbins make an angle of about 74°. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated.</p> + +<p class="ctr"><a href="./illustrations/11e.png"><img src="./illustrations/11e_th.jpg" alt=" FIG. 1. GRAY'S GALVANOMETER."></a></p><p class="ctr"> FIG. 1. GRAY'S GALVANOMETER.</p> + +<p>The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections.</p> + +<p>In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite.</p> + +<p class="ctr"><a href="./illustrations/11f.png"><img src="./illustrations/11f_th.jpg" alt=" FIG. 2."></a></p><p class="ctr"> FIG. 2.</p> + +<p>The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread.</p> + +<p>The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T<sup>1</sup>, T<sub>2</sub>, and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite.</p> + +<p>Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation.</p> + +<p>In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10<sup>4</sup> to 10<sup>5</sup> megohms could be measured +by the use of a pile of 120 daniells.</p> + +<p>The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier.</p> + +<p>The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one.</p> + +<p>We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane.</p> + +<p>Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.—<i>La Lumiere Electrique</i>.</p> + +<hr> + +<p><a name="29"></a></p> +<h2>HISTOLOGICAL METHODS.</h2> + +<p>A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required.</p> + +<p>Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly.</p> + +<p>Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol.</p> + +<p>The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol.</p> + +<p><i>Section cutting</i> machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument.</p> + +<p>A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal.</p> + +<p>When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed.</p> + +<p>With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose.</p> + +<p class="ctr"><a href="./illustrations/12a.png"><img src="./illustrations/12a_th.jpg" alt=" FIG. 1."></a></p><p class="ctr"> FIG. 1.</p> + +<p><i>To out a section by hand</i>, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush.</p> + +<p>When the object is too small to hold, it is usually <i>embedded</i> in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it.</p> + +<p>Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive.</p> + +<p>Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues.</p> + +<p>Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes.</p> + +<p>Much practice will be required before dexterity is attained.</p> + +<p><i>Methods of preserving the tissues</i>.—All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote.</p> + +<p>The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium.</p> + +<p>The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off.</p> + +<p><i>Preservative media</i>.—Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150°; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine.</p> + +<p>Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased.</p> + +<p>Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained.</p> + +<p>Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts.</p> + +<p>When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement.</p> + +<p><i>Preparation for mounting the different tissues</i>.—To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine.</p> + +<p>Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting.</p> + +<p>The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach.</p> + +<p>The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly.</p> + +<p>The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution.</p> + +<p>Every slide should be of uniform size, and labeled. The usual size is 3×1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required.</p> + +<hr> + +<p><a name="30"></a></p> +<h2>LIFE HISTORY OF A NEW SEPTIC ORGANISM.</h2> + +<p>At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of <i>Bacillus anthracis</i> and <i>Bacillus subtilis</i>, and <i>vice +versa</i>, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form—extending over four years—he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of <i>Bacterium termo</i>, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms—one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90° to 95° F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements.</p> + +<p>The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146° F., the highest point endured +by the germs was 190° F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the <i>modus operandi</i> was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law.</p> + +<hr> + +<p><a name="26"></a></p> +<h2>WINTER AND THE INSECTS.</h2> + +<p>For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellæ, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick.</p> + +<p class="ctr"><a href="./illustrations/13a.png"><img src="./illustrations/13a_th.jpg" alt=" GREEN WOODPECKER SEARCHING FOR INSECTS."></a></p><p class="ctr"> GREEN WOODPECKER SEARCHING FOR INSECTS.</p> + +<p>The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line—this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil.</p> + +<p>I now come to the effects of this severe cold upon the insects.</p> + +<p>The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellæ, in view of the +previous rarity of the individuals belonging to this family.</p> + +<p>We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvæ, pass this season upon the earth +enveloped in a silken envelope, or, like the larvæ of the Noctuellæ, +between dead leaves or upon the ground itself.</p> + +<p>On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvæ and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvæ of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera.</p> + +<p>It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvæ. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulæ are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvæ and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans—the wood lice.</p> + +<p>During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvæ and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvæ are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared.</p> + +<p>In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvæ feed and hibernate in the open air a few species of +Noctuellæ, whose larvæ live buried in the earth, are always abundant. The +country is relatively rich in spices of <i>Tortrix</i>, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.—<i>C.G. Barret, in Science et Nature</i>.</p> + +<hr> + +<p><a name="27"></a></p> +<h2>SILK WORM EGGS.</h2> + +<p>Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called <i>flacherie</i>, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs:</p> + +<p class="ctr"><a href="./illustrations/13b.png"><img src="./illustrations/13b_th.jpg" alt=""></a></p> + +<p>For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennæ, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths.</p> + +<p>There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3×6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room.</p> + +<p>The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day.</p> + +<p>When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered.</p> + +<hr> + +<p>Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine.</p> + +<hr> + +<h3>[NATURE.]</h3> + +<p><a name="24"></a></p> +<h2>DETERMINING THE MEAN DENSITY OF THE EARTH.</h2> + +<p>In <i>Nature</i> for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the <i>Nature</i> (Jan. 15. p. 260) report of the +<i>Proceedings</i> of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method.</p> + +<p>Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings.</p> + +<p>A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G.</p> + +<p class="ctr"><a href="./illustrations/14a.png"><img src="./illustrations/14a_th.jpg" alt=""></a></p> + +<p>In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance.</p> + +<p>The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary.</p> + +<p>ARTHUR KONIG.</p> + +<p>FRANZ RICHARZ.</p> + +<p>Berlin, Physical Institute of the University, March 15.</p> + +<hr> + +<p><a name="25"></a></p> +<h2>PHYSICS WITHOUT APPARATUS.</h2> + +<p><i>The Porosity and Permeability of Bodies.</i>—Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are <i>impermeable</i>, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so <i>penetrating</i>. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action.</p> + +<p class="ctr"><a href="./illustrations/14b.png"><img src="./illustrations/14b_th.jpg" alt=" Fig. 1.—EXPERIMENT UPON THE PERMEABILITY OF BODIES."></a></p><p class="ctr"> Fig. 1.—EXPERIMENT UPON THE PERMEABILITY OF BODIES.</p> + +<p><i>A Hot Air Balloon</i>.—Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.—<i>La Nature</i>.</p> + +<p class="ctr"><a href="./illustrations/14c.png"><img src="./illustrations/14c_th.jpg" alt=" Fig. 2.—PRINCIPLE OF THE HOT AIR BALLOON."></a></p><p class="ctr"> Fig. 2.—PRINCIPLE OF THE HOT AIR BALLOON.</p> + +<hr> + +<p><a name="23"></a></p> +<h2>THE CASINO AT MONTE CARLO.</h2> + +<p>The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea.</p> + +<p class="ctr"><a href="./illustrations/14d.png"><img src="./illustrations/14d_th.jpg" alt=" THE CASINO AT MONTE CARLO."></a></p><p class="ctr"> THE CASINO AT MONTE CARLO.</p> + +<p>Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces.</p> + +<p>But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player.</p> + +<p>It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined.</p> + +<hr> + +<p><a name="32"></a></p> +<h2>ON AN EXPRESS ENGINE.</h2> + +<p>It is a somewhat unpromising morning—the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance.</p> + +<p>So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead—the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed—it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades—for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart—where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.—<i>Saturday Review</i>.</p> + +<hr> + +<p>The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process.</p> + +<hr> + +<p><a name="31"></a></p> +<h2>ERYTHROXYLON.<a name="FNanchor14"></a><a href="#Footnote_14"><sup>[1]</sup></a></h2> + +<h3>COCA.</h3> + +<p>The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics.</p> + +<p>The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied.</p> + +<p>Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago.</p> + +<p>The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in <i>The Lancet</i> of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body."</p> + +<p>Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages.</p> + +<p>There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.<a name="FNanchor15"></a><a href="#Footnote_15"><sup>[2]</sup></a></p> + +<p>The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle—namely, caffeine—could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons.</p> + +<p>In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by.</p> + +<p>An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence.</p> + +<p>Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him.</p> + +<p>The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect.</p> + +<p>Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 2½ grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning.</p> + +<p>This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken.</p> + +<p>The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 2½ drachms did give a +definite effect, and a subsequent dose of 2½ fluid drachms of a well made +fluid extract of coca gave about the same effect as 2½ grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine.</p> + +<p>Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained.</p> + +<p>The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the <i>American Journal of +Pharmacy</i>, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows:</p> + +<p>Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent.</p> + +<p>Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory.</p> + +<p>Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid.</p> + +<p>From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process.</p> + +<p>Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle.</p> + +<a name="Footnote_14"></a><a href="#FNanchor14">[1]</a><div class=note>From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.</div> + +<a name="Footnote_15"></a><a href="#FNanchor15">[2]</a><div class=note>An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.</div> + +<hr> + +<p><a name="28"></a></p> +<h2>THE MELLOCO.</h2> + +<p>ULLUCUS TUBEROSA.—Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were.</p> + +<p class="ctr"><a href="./illustrations/16a.png"><img src="./illustrations/16a_th.jpg" alt=" MELLOCO TUBERS."></a></p><p class="ctr"> MELLOCO TUBERS.</p> + +<p>We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the <i>Gardeners' Chronicle</i> for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49°." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50° in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements.</p> + +<p>Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers—such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the <i>Gardeners' Chronicle</i> for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.—<i>W. Waston, Kew; +The Gardeners' Chronicle</i>.</p> + +<hr> + + +<p>A catalogue, containing brief notices of many important scientific papers +heretofore published in the SUPPLEMENT, may be had gratis at this office.</p> + + +<hr> + +<h2>THE SCIENTIFIC AMERICAN SUPPLEMENT.</h2> + +<h3>PUBLISHED WEEKLY.</h3> + +<p><b>Terms of Subscription, $5 a Year.</b></p> + +<p>Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country.</p> + +<p>All the back numbers of THE SUPPLEMENT, from the commencement, January 1, +1876, can be had. Price, 10 cents each.</p> + +<p>All the back volumes of THE SUPPLEMENT can likewise be supplied. Two +volumes are issued yearly. 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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific American Supplement, No. 492, June 6, 1885 + +Author: Various + +Release Date: June 2, 2004 [EBook #12490] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team + + + + +[Illustration] + + + + +SCIENTIFIC AMERICAN SUPPLEMENT NO. 492 + + + + +NEW YORK, JUNE 6, 1885. + +Scientific American Supplement. Vol. XIX, No. 492. + +Scientific American established 1845 + +Scientific American Supplement, $5 a year. + +Scientific American and Supplement, $7 a year. + + + * * * * * + + +TABLE OF CONTENTS. + +I. ENGINEERING AND MECHANICS.--The New Spanish Artillery.--2 + engravings. + + Qualitative Tests for Steel Rails.--By L. TETMAJER. + + A New Form of Small Bessemer Plant.--By A. TRAPPEN. + + Triple Compound Engines.--A paper read by A.E. SEATON + before the Institution of Naval Architects. + + Early History of the Steam Jack. + + Bridge over the River Adige, at Verona.--13 figures. + + Pumping Machinery.--Mine pumps.--Direct acting steam pumps. + By E.D. LEAVITT. + + Improved Gun Pressure Gauge.--2 figures. + + Measuring the Thickness of Boiler Plates. + + On an Express Engine. + + +II. TECHNOLOGY.--Improved Plaiting Machine.--With engraving. + + Self-acting Shuttle Guard.--1 figure. + + Ruler and Triangle for Hatching. + + The Distillation of Sea Water.--1 figure. + + Aids to Correct Exposure on Photographic Plates.--An + interesting paper by W. GOODMAN. + + Isochromatic Photography.--By FRED. E. IVES.--2 figures. + + Distortion from Expansion of the Paper in Photography. + + +III. ELECTRICITY, ETC.--On the Fritts Selenium Cells and + Batteries.--A paper read before the American Association + by C.E. FRITTS. + + Electricity Applied to the Manufacture of Varnish.--2 figures. + + Naglo Brothers' Telephone System.--3 figures. + + The Gerard Electric Lamp.--1 figure. + + A New Reflecting Galvanometer.--3 figures. + + +IV. ART AND ARCHITECTURE.--Groups of Statuary for the Pediment + of the House of Parliament in Vienna.--2 engravings. + + The Casino at Monte Carlo.--An engraving. + + +V. PHYSICS.--Determining the Density of the Earth.--1 figure. + + Physics without Apparatus.--The Porosity and Permeability of + Bodies.--A Hot Air Balloon.--2 engravings. + + +VI. NATURAL HISTORY.--Winter and the Insects.--An engraving. + + Silk Worm Eggs.--With engraving. + + +VII. HORTICULTURE.--The Melleco.--Ullucus tuberosa.--With + engraving. + + +VIII. PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section + cutting machines.--Methods of preserving the + tissues.--Preservative media.--Preparation for mounting + tissues.--1 figure. + + Life History of a New Septic Organism. + + Erythroxylon Coca as a Therapeutic Agent.--By Dr. E.R. SQUIBB. + + * * * * * + + + + +NEW SPANISH ARTILLERY. + + +The Spanish Government is now engaged in supplying some of its principal +fortifications with heavy guns of the most improved construction. The +defenses of Cadiz and Ceuta have been greatly strengthened in this +respect. The most recent additions are some very powerful Krupp guns for +the fortress of Isabel II., at Mahon. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +We give engravings from photographs, as presented in _La Illustracion +Espanola_. These guns are breech loaders, of steel, 301/2 centimeters +caliber, or 12 inches, 49 tons weight. + +[Illustration: NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.] + +One of our engravings shows the great revolving crane by which the guns +were lifted and placed on the truck for conveyance over a track to their +intended position. This crane is worked by eight men, and readily lifts +burdens of about 200,000 lb. The other engraving shows the jack frame and +jacks employed to remove the gun from the temporary truck. At a range of +7,000 yards these guns are able to penetrate iron plates of two feet +thickness. + + * * * * * + + + + +QUALITATIVE TESTS FOR STEEL RAILS. + +By Mr. L. TETMAJER. + + +This memoir is the first of a series upon the unification of nomenclature +and classification of building materials, undertaken by the author at the +request of the Swiss Engineers' and Architects' Union. For its +preparation numerous mechanical tests have been made upon steel rails, +both good and bad, taken from the Swiss railways, while the corresponding +chemical analyses have been made by Dr. Treadwell in the Polytechnic +Laboratory, at Zurich. The results are given for twenty-two examples, +about one-half of which have stood well, while the remainder have either +broken, split, or suffered considerable abrasion in wear; but in many +instances the mechanical test of tensile strength, elongation, and +contraction, and the figures of quality (Wohler's sum and Tetmajer's +coefficient) deduced from these have varied very considerably for the +results obtained in practice. + +The best wearing rails, which often give contradictory results with the +tensile test, were comparatively pure manganese steels, low in silicon, +only exceptionally up to 0.2 per cent., but generally below 0.1 per +cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the +other hand, rails with a tendency to break or split are low in carbon, +with variable proportions of manganese, but contain much silicon, 0.3 to +0.9 per cent., and often above 0.1 per cent. of phosphorus. Another +series of experiments upon rails for the Finland lines made by the author +in 1879-80 shows the high quality of manganese steel. These are +essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 +per cent. manganese, and have stood three and a half years' wear without +a single one being broken; while those of silicon steel with 0.106-0.144 +per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have +failed in many cases, showing a great tendency to split. In both of the +latter instances, however, the figures deduced from tensile tests of both +good and bad specimens were substantially the same. + +The causes of the difference between the two kinds of steel the author +attributes to differences in the structure of the ingot due to the agent +used in "chemical consolidation," which may be either manganese or +silicon, which structures are illustrated by photographs of ingot +fractures. When silicon is used there is a tendency to unsoundness about +the exterior of the ingot, which is surrounded by a honeycomb-like +cellular casing of greater or less depth; while with manganese the +vesicular cavities are more or less dispersed through the whole +substance, or concentrated toward the interior of the ingot. Rails made +from the former are, therefore, more likely to contain unsound portions +near the outer wearing surface, and to give unsatisfactory results in +wear, than those from the latter; but as the test pieces are usually cut +from the center of the railhead, the tensile resistance of the interior +may be equal to or surpass that of the superior material. In summing up +his observations the author concludes that the method of tensile testing +is mainly of value in determining the quality of the material, but that +for the finished product properly arranged falling weight tests are +necessary. He also considers that the test pieces should be flat bars of +2.5 to 3.5 centimeters in area, cut as near as possible to the outer +surface of both head and foot of the rail. He reprobates especially the +research for microscopic imperfections (mikrobensuecherei) upon the +fractured surfaces, as an annoyance to the producer, and perfectly +useless to the consumer.--_Stahl und Eisen_, vol. iv., page 608; through +_Proc. Inst. Civ. Eng_. + + * * * * * + + + + +A NEW FORM OF SMALL BESSEMER PLANT. + +By Mr. A. TRAPPEN. + + +The success of the Bessemer process when carried out on the small scale +at Avesta in Sweden, as described by Professor Ehrenwerth, and subsequent +experiments of a similar kind made at Pravali, in Carinthia, and +elsewhere, have led the author, who is specially occupied in the building +of Bessemer works, to design a plant suitable for operation upon small +charges. This consists essentially of a converter about 1 meter outside +diameter, and 1.5 meters high, connected by a single trunnion to a +horizontal steel shaft carried by the arm of a hydraulic crane which is +very similar in character to the ladle crane of a large sized converter. +The sweep of the crane is such as to allow the converter to be brought +close up to the tap hole of the blast furnace or cupola, so that the use +of open gutters for the fluid metal may be avoided as much as possible. +The converter is turned on its axis by a screw and worm wheel, which is +manipulated by a workman standing on a platform at the opposite arm of +the crane. The blast is brought in from above by a pipe down the central +pillar of the crane, which is connected with the blast-main by a flexible +tube and packed joint. The outer trunnion bearing is open, so that by +slightly raising and lowering the ram of the crane, the converter may be +left suspended to a weighing machine in front of the furnace, if it is +required to determine the weight of the charge. When the converter is +filled, it is borne by the crane into a convenient position for blowing, +and if the basic method is followed for removing the slag, the converted +metal is cast into ingot moulds, which are manipulated by a small ingot +crane of the ordinary pattern. In the case of small existing +blast-furnaces, which usually have their tap holes near to the ground, it +may be necessary to have a shallow ingot pit (20 to 24 inches deep); but +with cupolas this will not generally be necessary, and the whole of the +operations may be carried on at the ground level. Each crane is intended +to be supplied with two or three converters, so that operations may be +carried on continuously. The weight of charge proposed is 15 cwt., which +should under ordinary conditions give 12 cwt. of ingots. Taking the time +of a single converting operation at half an hour it will be easy to +obtain fifty blows per day, or a production of 30 tons. This may be +easily increased by placing a second converting crane on the other side +of the furnace, for which the same blowing engine will be sufficient, as +the actual blowing time will not exceed twelve minutes. The labor +required for each converter will be about six men per shift. + +The blast required has been experimentally determined at 40-50 cubic +meters per minute at 15 lb. pressure. This will be supplied by a single +cylinder engine of 900 millimeters blast, and 786 millimeters steam +piston, diameter 786 millimeters, stroke making fifty revolutions per +minute, which is also to work a Root blower and the accumulator pumps. +Having regard to these very different demands upon the power of the +engine, it will be provided with expansion gear, allowing a considerable +variation in the cut-off. A single boiler of 70 to 75 square meters +heating surface will be sufficient. The accumulator is intended to work +at 300 lb. pressure. + +The cost of the plant, including one of each of the following items, +converter, converter truck, blowing engine, accumulator, ingot crane, +centesimal weighing machine, and accumulator pump, is estimated at L2,050 +to L2,100; and that of the steam boiler, L325. The buildings may be of +the simplest and cheapest possible character. As the productive power of +such a plant contrasts very favorably with its cost, the author considers +that it may be fairly expected to meet the competition of large works, +especially in the manufacture of a high-class product.--_Stahl und +Eisen_, vol. iv., page 524; through _Proc. Inst. Civ. Eng_. + + * * * * * + + + + +TRIPLE COMPOUND ENGINES. + +[Footnote: Paper read before the Institution of Naval Architects, March +27, 1885.] + +By Mr. A.E. SEATON. + + +My attention was first called to the modern triple compound engine by the +published reports of the trial trip of the yacht Isa, and in it I plainly +discerned the germs of a successful new type of engine; but it was not +until I had seen the engines of the screw steamer Aberdeen erected in the +workshops of Messrs. Robert Napier & Sons that I became convinced that it +was the engine of the immediate future. It is, however, due to the +farsightedness and enterprise of Mr. C.H. Wilson, M.P., that I was +enabled to try the merits of the new system and compare it with the old. +Mr. Wilson had already viewed the triple compound engine with more than +ordinary interest, and it required little persuasion on my part to allow +the company to which I have the honor to belong to construct a triple +expansion engine in lieu of the ordinary compound for one of four sister +ships which it then had in hand for Messrs. Thomas Wilson, Sons & Co., +the latter only stipulating that it was to be of the same power as the +engine already contracted for. As I was quite convinced that economy was +due to the system rather than to the higher pressure, it was decided not +to increase the boiler pressure more than was necessary to suit the +triple system. The other three ships already alluded to were being fitted +with engines having cylinders 25 inches and 50 inches diameter by 45 +inches stroke, and supplied with steam of 90 lb. pressure from a double +ended boiler 13 feet 9 inches diameter by 15 feet long, having a total +heating surface of 2,310 feet, so that these engines have every +qualification for being economical so far as general proportions go, the +stroke being an abnormally long one and the boiler of ample size. +Experience has since shown that these engines are economical in coal, +and the wear and tear exceptionally small. + +The new engines for the fourth boat were made with considerably shorter +stroke, and the cylinders proportioned so as to give equal power; they +are 21 inches, 32 inches, and 56 inches diameter by 36 inches stroke, the +high pressure cylinder being supported on columns immediately over the +medium cylinder, and in other respects these engines were made as near as +possible like the other ones above named. Steam at 110 lb. pressure is +supplied from a double ended boiler 12 feet 9 inches diameter and fifteen +feet long, having a total heating surface of 2,270 square feet, and +identical in design with the boiler supplied for the other engines. The +propellers were made exactly alike in all respects, and the ships being +likewise precisely alike, a comparison of the performances of the one +fitted with the triple engines could be made with as little grounds for +differences of opinion as is possible. One of the ships fitted with the +ordinary compound engines was named the Kovno, that with the triple +compound engines the Draco. Their dimensions are as follows: + + Feet. Inches. +Length between perpendiculars. 270 0 +Breadth. 34 0 +Depth of hold. 18 3 + +And of 1,700 tons gross register. They are ordinary cargo boats, built of +steel, having a raised quarter deck and long bridge amidships, but +nothing about them otherwise requires comment. + +After making a voyage or two to the Baltic, and finding that everything +was working satisfactorily, the Kovno was loaded with 2,400 tons dead +weight, and sailed in January, 1883, for Buenos Ayres; the Draco was +loaded with 2,425 tons dead weight, and sailed March, 1883, for Bombay, +the distance in both cases being about 6,400 miles. It was thought +advisable, for purposes of comparison, that the ships should steam at as +near as possible the same speed; and to attain this object, we considered +the safest plan was to instruct the engineers as to the average amount of +coal they were to burn per day, and experience with these ships on their +Baltic voyages had fixed this at 12 tons in the case of the Kovno and 10 +tons in the case of the Draco. During the voyage each ship seems to have +had fair average weather, and equal care was taken in getting the best +results possible. The average speed of the Draco was, however, 8.625 +knots, or 207 miles per day, the engines making on the average 57.5 +revolutions per minute, while the Kovno did only 8.1 knots, or 194 miles +per day, the engines making 55.5 revolutions. The coal used was ordinary +South Yorkshire, just as it comes from the pits for bunker purposes. The +indicated horse power in each case would average about 600. The total +coal consumed was 326 tons in the Draco and 405 tons in the Kovno, or a +saving of 19.5 per cent. over the ordinary compounds, with an increase of +speed of 6.5 per cent. + +In December, 1883, one of the others, the Grodno, sailed from Bombay, and +attained an average speed of 8.5 knots, or 204 miles per day, the engines +making 57 revolutions, with a coal consumption of 12.8 tons per day, or +469 tons on the voyage. The Draco's consumption is therefore 30.5 per +cent. less than that of the Grodno on the round voyage, and 20.3 percent +per day. + +The success of the triple compound engine was in these instances more +than had been anticipated, and induced Mr. Wilson to go a step further. +The S.S. Yeddo had been refitted with boilers made for a working pressure +of 90 lb. per square inch, but owing to the size of the shafting the +working pressure was limited to 70 lb.; the average consumption of coal +under these circumstances on two voyages was 17 tons per day. These +boilers had a margin of safety beyond what was required by the rules when +made, and as the Board of Trade rules had been modified in the mean +while, it was found that they could with safety be worked at 100 lb. per +square inch. A third cylinder was now fitted on the top of the original +low pressure, and the safety valves loaded to the 100 lb., and the ship +was dispatched to Cronstadt. After making two voyages under similar +circumstances to the two previous ones, the average consumption was 13.5 +tons per day only. In this case it was the same ship, same boilers, same +engines, same propeller, and same men, the only difference being the +addition of a third cylinder and the increase of pressure. + +So far all the trials had been made with two crank engines; so it was now +decided to construct another set of engines for 150 lb. pressure, having +a crank to each cylinder. These engines had cylinders 201/2 inches, 33 +inches, and 58 inches diameter by 36 inches stroke, and were fitted into +the screw steamer Rosario, whose dimensions are 275 feet 3 inches between +perpendiculars, 34 feet 3 inches beam, and 19 feet 2 inches depth of +hold, 1,862 tons gross, and the deadweight capacity 2,550 tons. In March +last year she was loaded with 2,530 tons deadweight, and did the voyage +to Bombay at an average speed of 8.6 knots on a consumption of 10.5 tons +per day of South Yorkshire coal, and burnt on the voyage 347 tons. This +result is superior to that of the Draco when the size of the ship is +taken into account, but is not so much so as might have been anticipated +from the increase of pressure and the rate of expansion, which was 14.4 +in the Rosario and 12 in the Draco. Another set of engines was made from +the patterns of those of the Draco, but with the high pressure cylinder +20 inches diameter, steam at 150 lb. pressure being supplied from two +single ended boilers, having a total heating surface of 2,200 square +feet. They are fitted in the S.S. Finland, a cargo boat 270 feet long, 35 +feet beam, by 18 feet depth of hold, and 1,954 tons gross register. In +January she was loaded with 2,500 tons deadweight, and sailed for +Rangoon. The average speed attained was 8.42 knots per hour, or 202 miles +per day, on a consumption of 10.3 tons of Welsh coal per day, the rate of +expansion being 12. It should be mentioned that all these ships named are +fitted and steered with steam stearing gear, so that in comparing these +results and those published of the engines made by an eminent engineer in +the north of England, an allowance should be made, as in that ship there +was no steam stearing gear. + +I have chosen to make all these comparisons by reference to the ships' +logs, and to give results such as a shipowner looks for rather than those +which engineers prefer to use in forming a judgment on the merits of +different engines. I do this for two reasons: first, because the +commercial success of the triple compound engine depends on the saving it +can effect in a long voyage; and secondly, because I had no reliable +indicator diagrams from which the consumption per indicated horse power +could be calculated with any degree of accuracy. On trial trips with the +steamers already named, the consumption of ordinary South Yorkshire coal +was 1.6 lb. per indicated horse power, and the consumption of water per +indicated horse power calculated from the high pressure indicator +diagrams was 1.41 in the Draco, 13.2 in the Rosario, and 13.16 with the +Finland, or taking the medium pressure diagrams, it was 12.2, 1.30, and +11.95 respectively. Twelve months ago we constructed for Messrs. Thomas +Wilson, Sons & Co., two sets of triple expansion engines of 600 indicated +horse power, one having two cranks and the other three cranks, the +engines, boilers, and propellers being otherwise exactly alike and fitted +into sister ships. The water consumed in the three crank engine is 12.93 +lb., against 13.0 in the two crank, but the former drives its ship nearly +1/2 knot per hour faster than the latter does its, and when both ships are +driven at the same speed the consumption of coal in the three crank ship +is considerably less than in the other. + +We have now entirely given up the construction of two-crank triple +expansion engines, because of the impossibility of equally dividing the +work between the cranks; for, although the engine when running appeared +to be perfectly balanced, the wear of the brasses of the crank having the +two cylinders was always considerably more than that of the other. +Placing the high pressure cylinder over the low pressure cylinder seemed +to give the most satisfactory results, but even these were far inferior +to those once obtained with the three cranks. We have lately constructed +some very small three-crank engines from which exceedingly good results +were obtained; the cylinders are only 111/2 inches, 17 inches, and 30 +inches by 18 inches stroke, which developed 218 indicated horse power +with a consumption of 12.8 lb. of water per indicated horse power, and +this, together with some other observations, leads me to believe that the +best economical results will be obtained by running triple expansion +engines at a much higher number of revolutions than is usual, and with a +rate of expansion not less than 12 for a steam pressure not less than 140 +lb. (155 absolute). The largest engines we have made of this type so far +are those of S.S. Martello, which have cylinders 31 inches, 50 inches, +and 82 inches diameter by 57 inches strokes and indicate at sea 2,400 +horse power when running at 60 revolutions with steam of 150 lb. +pressure; the consumption of Yorkshire coal is 37 tons per day average +throughout a New York voyage. Had Welsh coal been used in every case, the +results would have been very much better, for, in addition to the +superior evaporative power of Welsh coal, it is slow burning and much +more easily controlled, especially on the comparatively short grates of +these modern boilers, the quick-burning Yorkshire coal causing the safety +valves to frequently blow off when working near the load pressure unless +great care is taken by the firemen. + +I trust these few particulars may be of interest to the Institution, and +especially to those members of it who are particularly interested in the +commercial success of our mercantile navy. I have purposely avoided +engineering details and technicalities of any kind, giving only such +information as will tend to give British shipowners faith in that form of +engine which will undoubtedly help them to successfully tide over bad +times, and keep the bulk of the carrying trade of the world in their +hands. + + * * * * * + + + + +EARLY HISTORY OF THE STEAM JACK. + +_To the Editor of the Scientific American:_ + + +A friend has brought me a copy of the SCIENTIFIC AMERICAN SUPPLEMENT, of +April 18, 1885, containing an article about a "steam jack." + +Says Mr. J.G. Briggs, in the _American Engineer:_ "Of its origin nothing +is known." Also the invention is attributed to "Benjamin Baleh." I can +give you the true history of the "steam jack." It was invented by my +grandfather, John Bailey, of Hanover, Plymouth County, Mass. He was a +minister of some note in the Society of Friends, or Quakers.--a man of +superior mental ability, but poor in purse, for, like all early +inventors, he reaped but little pecuniary benefit from his inventions. +Among those inventions was the first iron sink in this country--if not in +the world. A few years ago that sink was in use at his old home in +Hanover. He also invented the crooked nose for the tea-kettle. Previous +to that the nose was straight. Both sink and tea-kettle were cast at the +Middleborough foundry. When he made the steam-jack he said, "In less than +fifty years the common mode of travel would be by steam." People called +him "steam mad." But about the jack. We have one in our possession of +which your cut is an exact copy. We have used it several times. We also +have the parchment _patent_, of which I send you a copy. The jacks were +not in general use, for soon after the invention the "tin kitchen," or +"Dutch oven," as it was sometimes called, was introduced, and superseded +the jack entirely, as people were afraid of being blown up by steam. The +patent says, "John Bailey, of Boston," showing that at that early date +Boston was considered the _Hub_, and that it was considered a good thing +to hail from there. Hanover is about twenty-four miles from Boston. + +Trusting I have not wearied you, I am, + +ANNA M. BAILEY. + +Bleak House, Lynn, Mass., May 12. + + +COPY OF PATENT. + +_United States_. + +To all to whom these Presents shall come, Greeting. Whereas, John Bailey, +of Boston, in the State of Massachusetts, hath presented a petition to +the Secretary of State, the Secretary for the Department of War, and the +Attorney-General of the United States, alledging and suggesting that he +hath invented the following useful Machine, not before known or used, +that is to say: A Steam Jack, consisting of a boiler, three wheels, and +two wallowers; the steam which issues from boiling water in the said +boiler gives motion to one of those wheels by striking on buckets on its +circumference; on the outer end of the axle of the wheel is a wallower, +the rounds of which fall into the teeth of a second wheel; on the axle of +this second wheel is another wallower, the rounds of which fall into the +teeth of a third wheel; on the axle of which third wheel is a spit: and +praying that a patent may be granted therefor: and, whereas, the said +invention hath been deemed sufficiently useful and important: These are, +therefore, in pursuance of the Act, intitled an Act to promote the +progress of useful arts, to grant the said John Bailey, his heirs, +administrators, or assigns, for the term of fourteen years, the sole and +exclusive right and liberty of constructing, using, and vending to others +to be used, the said invention so far as he the said John Bailey was the +inventor, according to the allegations and suggestions of the said +petition. In Testimony whereof I have caused these Letters to be made +patent, and the Seal of the United States to be hereunto affixed. Given +under my hand, at the City of Philadelphia, this twenty-third day of +February, in the year of our Lord one thousand seven hundred and +ninety-two, and of the Independence of the United States of America the +Sixteenth. Go. WASHINGTON. + +By the President, + +TH. JEFFERSON. + + +CITY OF PHILADELPHIA, February 23, 1792. + +I do hereby certify that the foregoing Letters-patent were delivered to +me in pursuance of the Act intitled an Act to promote the progress of +useful arts: that I have examined the same, and find them conformable to +the said Act. + +EDM. RANDOLPH, + +_Attorney-General of the U.S._ + +[SEAL.] + + * * * * * + + + + +BRIDGE AT VERONA. + + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The iron bridge which spans the Adige at Verona, of which we publish +illustrations, has been recently completed to replace an old masonry +bridge built in the fourteenth century, and which was destroyed by the +celebrated flood of 1882. In designing the new work two leading +conditions had to be fulfilled, namely, that there should be a single +opening of 291 ft. between abutments, and that this width should be left +quite unobstructed, for the river is subject to floods, which are +frequent, and very violent and sudden. For this latter reason an ordinary +form of arch, with the roadway above it, was inadmissible, since the +waterway would be seriously obstructed; the special form illustrated was, +therefore, carried into execution. The bridge, as will be seen from Figs. +1, 2, 3, and 7, consists of two main arched girders, with two vertical +sides in lattice work; these arches spring below the level of the roadway +and rise to a considerable height above it, in the center. The horizontal +girders carrying the roadway, are connected to the arches by verticals of +the form and section shown in the drawings. The longitudinal girders are +of double trellis, as will be seen by reference to Figs. 1, 12, and 16. +The following are the principal dimensions of the bridge: + + Ft. In. +Clear opening between abutments 291 4 +Rise of arch 32 93/4 +Width of bridge 37 43/4 +Depth of arched girders 4 7 + +[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.] + +The arched girders are connected together, in the central portion, by a +system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage +road on the platform consists of buckled plates resting on transverse +girders spaced 6 ft. 6 in. apart, and covered with road metal, and for +the sidewalks checkered plates are used. The ironwork in the bridge +weighs 400 tons, and cost 8,400 _l._; the abutments cost 3,600_l._, +making the total outlay on the structure 12,000_l_. The bridge was +tested by a uniformly distributed load of 82 lb. per sq. ft., and under +this stress the arched girders deflected 1.06 in. The horizontal and +vertical oscillation of the bridge, which were carefully observed and +graphically recorded by special instruments, were very slight. The +engineer of the work was Mr. G.B. Biadego, of Genoa.--_Engineering_. + + * * * * * + + + + +PUMPING MACHINERY. + +[Footnote: A paper read at the Montreal Meeting of the British +Association.] + +By E.D. LEAVITT, JR., Cambridgeport, Mass. + +MINE PUMPING MACHINERY. + + +One of the earliest steam engines, of any size, introduced into America, +was erected about the year 1763, at the Schuylkill copper mine, situated +upon the Passaic River, in New Jersey. All its principal parts were +imported from England; and a Mr. Hornblower (the son, it is believed, of +the well known engineer of that name) came to this country for the +purpose of putting up and running this engine. + +At the time when the manufacture of the engines for the Philadelphia +Water Works was commenced, and as late as the year 1803, we find five +engines, in addition to the one above mentioned, noticed as being used in +this country: two at the Philadelphia Water Works; one just about being +started at the Manhattan Water Works, New York; one in Boston; and one in +Roosevelt's sawmill, New York; also a small one used by Oliver Evans to +grind plaster of Paris, in Philadelphia. Thus, at the period spoken of, +out of seven steam engines known to be in America, four were pumping +engines. + +In the coal regions of Pennsylvania, a simple, high pressure, single +acting Bull engine has been extensively adopted; the dimensions usually +run from 36 inches to 80 inches in diameter, and a very common stroke is +10 feet. At the Empire shaft, in the Schuylkill coal region, there is a +very fine pair of these engines, with 80 inch cylinders, working 24 inch +pumps. The stroke of both steam pistons and pumps is 10 feet. These Bull +engines are placed either vertically or on an incline, as is most +convenient for the workings. The water valves are made either double, +triple, or four beat, according as the pumps are large or small; and the +beats are usually flat, and faced with leather. Many flap-valves are also +in use. These are frequently arranged on conical seats, and work very +well. + +The Bull engines, from their strength and simplicity, give very little +trouble, working year after year with astonishing freedom from accident +and slight cost of repair. No attempt is made to economize fuel, which +consists mainly of culm, which would otherwise be wasted. Of late, direct +acting steam pumps placed under ground have found much favor with mine +operators, on account of their portability and small first cost. They +usually range in size from 8 inch steam and 5 inch water cylinders by 12 +inch stroke to 80 inch stream and 14 inch water cylinders by 36 inch +stroke. Great numbers of these pumps are in use all over the United +States. + +A pumping engine that is remarkable for its size and peculiarities of +construction is located at the Lehigh zinc mine, at Friedensburg, Pa. It +was designed by Mr. John West, the company's engineer, and built by +Merrick & Sons, of the Southwark Foundry, Philadelphia. It is a beam and +fly-wheel engine, the steam cylinder being 110 inches in diameter, with a +stroke of 10 feet. There are two beams on the same main center, from the +outer end of which a double line of bucket and plunger pumps is operated. +The crank-shaft is underneath the steam cylinder; and there are two +fly-wheels, one on each end of said shaft, the crank-pins being fast in +the hubs of the same. There are two connecting rods, which are attached +one to each end of an end beam pin 28 inches in diameter. The main center +and crank shafts are also 28 inches in diameter; each of the two plunger +holes is 24 inches by 30 inches in section; and all the working parts are +in proportion to those heretofore mentioned. + +Perhaps no mining district has ever had to contend against greater +difficulties in pumping than have faced the engineers of the celebrated +Comstock lode, Virginia City, Nev. The mines are of great depth, in some +instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr. +The machinery collected at this location is of great variety and +magnitude. There are many Davey engines, both horizontal and vertical. +The Union and Yellow Jacket shafts have compound fly wheel engines of +very great power; the former having a beam, and the latter being +horizontal, with cylinders placed side by side, and pistons connected to +a massive cross-head, from the ends of which connecting rods lead to +crank pins located in the hubs of the fly-wheels, which are overhung upon +the ends of the main shaft. From the center of the cross head, a link +runs to the main pump-bob, which operates a double line of 16 inch pumps, +10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet. + +The pumping machinery used in the iron and copper districts of Michigan +usually consists of Cornish plunger pumps, which are operated by geared +engines; the latter making from three to sixteen strokes to one of the +pumps. + +The largest plant of this type yet erected is that of the Calumet and +Hecla copper mine, at Calumet, Mich. There are two lines of pumps, +varying in diameter from 7 inches to 14 inches, and with an adjustable +stroke varying from 3 feet to 9 feet. The object of the adjustable stroke +is to diminish the capacity of the pumps in the dry season. Each line of +pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches +in diameter, making ten revolutions per minute. The mortise spur-wheels +have a diameter of 221/2 feet at the pitch line, with two rows of teeth, +each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise +wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on +steel shafts 12 inches in diameter, and making 50 revolutions per minute. +The 12 inch pinion shafts are driven through mortise wheels 12 feet in +diameter, and 24 inches face, by pinions 3 feet 9 inches diameter, which +make 160 revolutions a minute. The pinion shafts are driven through a +wire rope transmission from an engine located 500 feet distant. The rope +wheels are 15 feet in diameter, and make 160 revolutions a minute. The +engine is 4,700 horse power, and, in addition to driving the pumping +machinery, does the hoisting and air compressing for the Calumet mine. + +In the same building with the mine pump gearing is a duplicate +arrangement for operating the man engine. In order to operate the mine +pumps and man engine for the Hecla mine, it was necessary to use rock +shafts, which are made of gun iron, and hollow; they are 32 inches in +diameter outside, with 41/2 inches thickness of metal. The pump rock shaft +is 39 feet 41/2 inches long over all, in two sections, and weighs 40 tons. +There are rockers placed on each end of this shaft, one of which is +connected with a crank on the mortise wheel shaft, and the other with the +surface rods that work the pump-bobs. These rods are of Norway pine, 12 +inches by 12 inches in section, and 1,000 feet long. There are two bobs, +one above the other, with axes at right angles, each weighing about 25 +tons. The connection from the upper bob to the lower has hemispherical +pins and brasses to accommodate vibrations in right angled planes. The +slope of the main pump is 39 degrees, and the machinery has been designed +to raise water from 4,000 feet depth. The pumps are of the usual Cornish +plunger type, with flap valves. There is an auxiliary engine, of the +Porter-Allen type, for driving the pumps and man engines when the main +engine is not working. It makes a 160 revolutions per minute, the same as +the rope wheels The seeming complication of the arrangement is due to the +fact that it had to be adapted to existing works, for increased depths, +and put in without interfering with the daily operation of the mine. + +The Calumet & Hecla Mining Company has also an extensive pumping plant at +its stamp mills, which are located on the shore of Torch Lake, about four +and a half miles from the mine. There are located here 3 pumping engines; +two of which have a capacity of 20,000,000 gallons a day, and a third +10,000,000 gallons a day. The water is elevated between 50 and 60 feet, +and is used for treating the stamped rock. Two of the engines are of the +inverted compound beam and fly-wheel type; and the third is a geared +pump, which has a horizontal double acting plunger, 36 inches in +diameter, by six foot stroke, driven from the crank of a spur-wheel +shaft. + +The spur wheel is 12 feet diameter, 24 inches face, and contains 96 +teeth. The pinion engaging with it has 27 teeth, and is fast on the +fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches +in diameter, and a stroke of four feet. The steam pressure used is 110 +pounds per square inch; and the engine has a Buckley condenser. The pump +valves are annular, of brass, faced with rubber, and close by brass +spiral spiral springs. Their external diameter is six inches, and the +lift is confined to 1/2 inch. There are 91 suction and 91 delivery valves +at each end of the pump. The maximum speed of this pump is twenty-six +double strokes a minute. + +The largest of the compound engines is named Ontario, and has a vertical +low pressure cylinder 36 inches in diameter, and an inclined high +pressure cylinder 171/2 inches in diameter; the stroke of both being five +feet. These are inverted over a beam, or rocker; and the pistons are +connected to opposite ends of the same. + +The beam attachment of the main connecting rod is made to a pin located +above and midway between the pins for piston connections. + +The main center of the beam and the crank shaft have their pedestals in +the same horizontal plane. The throw of the crank is five feet. There are +two differential plunger pumps, having upper plungers 20 inches in +diameter, and lower plungers 33 inches in diameter, with a stroke of 5 +feet. These pumps are vertical, and placed beneath the engine bed-plate, +to which they are attached by strong brackets. The pump under the low +pressure cylinder is worked directly from its cross-head by an extension +of the piston rod. The other pump is worked by a trunk connection from +the opposite end of the beam. The radius of the beam is but fifty inches, +but the connections to it are made very long by links. + +The lower plungers work through sleeves in diaphragms located in the +center of the pumps. In these diaphragms, the openings for the delivery +valves are made. These valves are similar in construction to those +previously described for the horizontal plunger pump. Their diameter, +however, is but 51/4 inches, instead of 6 inches, and there are 72 suction +and 72 delivery valves for each pump. It will readily be seen that the +action of these pumps is similar to that of the bucket and plunger; each +pump having one suction and two deliveries for each revolution of the +engine. The Ontario is designed to run at a maximum speed of 33 +revolutions a minute; and the service required of it is to run regularly +144 hours a week, without a stop, which is performed with the utmost +regularity. + +The differential pump was invented and patented, many years since, by a +party named James Ramsden, in Pennsylvania, who designed it for an +ordinary house pump. It was subsequently reinvented by the writer, who +first ascertained that he was not the original inventor upon applying for +a patent. A pump of this description was run at the Hecla mine for +several years, at a speed of 500 feet a minute; and its performance was +in every way satisfactory. + + +DIRECT ACTING STEAM PUMPS. + +This class of machinery deserves a prominent place, as the number in use +vastly exceeds those of all other types combined. + +The first consideration will be given to the Worthington, which is the +pioneer of its type, having been invented by the late Henry R. +Worthington, and patented in 1844. Mr. Worthington's first pump was +designed for feeding boilers. His first water works engine was built for +the city of Savannah, Ga., and erected in 1854. The second engine, which +was the duplicate of the Savannah engine, was erected at the city of +Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 +gallons in twenty-four hours to an altitude of 100 feet. It had a high +pressure cylinder 12 inches in diameter, placed within a low pressure +cylinder 25 inches in diameter; the low pressure piston being annular. +The double acting water plunger was 14 inches in diameter, and worked +directly from the high pressure piston rod; the stroke of pistons and +plunger being 25 inches. This engine was tested in 1860, with the result +of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. +Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long +prominently connected with the Philadelphia Water Department), and the +late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot +pounds per 100 pounds of coal, which long remained the best record in the +United States. In 1863, Mr. Worthington brought out at Charleston, Mass., +his crowning success, the duplex engine, which fairly deserves to be +placed first among the hydraulic inventions of this century. This engine +has since been more extensively duplicated for water works purposes than +any other, with the possible exception of the Cornish. + + * * * * * + + + + +IMPROVED GUN PRESSURE GAUGE. + + +The following description of the construction and mode of action is by +Thomas Shaw, M.E., Philadelphia, the inventor. + +[Illustration: IMPROVED GUN PRESSURE GAUGE.] + +Fig. 1 represents the gauge secured to small ordnance, the gun shown in +cross section. Fig. 2 represents face view of the gauge and indicator, +exposing a vertical section through the hydraulic portion of the gauge, +on line 3 and 4 of Fig. 1. The same principles of reduction of high +pressure are used in this gauge as in Shaw's hydraulic gauge. It will be +observed that a solid steel piston, E, in the cylinder, A, is provided +with a plunger on its under side, which comes in contact with an elastic +packing, D; the plunger may stand as 1 to A 1,000, or as 1 to A 100, in +point of area of exposed surface, as compared with the large piston head, +as desired. Assuming the proportions to be 1 to A 1,000, the 1,000 lb. +pressure on the plunger means only 1 lb. pressure in the fluid chamber, +above piston head, E, and this greatly reduced pressure is now +susceptible of measurement by any of the ordinary light pressure +instruments for measuring pressures. All the passage ways connecting to +dial gauge, R, with the fluid chamber above piston, E, are filled solid +with fluid, permitting no air spaces that can be avoided. The steel plug, +L, that forms a passage way between the fluid chamber and the dial gauge, +is provided on one side with a small screw hydraulic pump, with a +reservoir supply of fluid. This part is shown in longitudinal section; +the steel plunger, I, is firmly secured to wheel, F, the long hub, H, of +which is provided with a screw thread on its inner side, which thread +screws upon the exterior of pump barrel, K. After first filling the +interior of the pump barrel with fluid, the said hub is screwed upon the +pump barrel, causing the plunger, I, to force the fluid into the fluid +chamber and passage way leading to the dial gauge, causing the hand or +pointer to move to any predetermined pressure on dial, in advance of +pressure applied in the high pressure chamber at D. The purpose +accomplished in this act is to give the least possible movement of the +pointer to record any maximum pressure, as, for example, assuming that +20,000 lb. was the expected pressure from any one explosive, then the +pointer, by the means above described, can be set at, say, 18,000 lb., in +which event the pointer is reduced to the minimum movement of only 2,000 +lb. to register 20,000 lb. + +It will be evident that much greater accuracy of measurement of maximum +pressures can be obtained by the minimum movement of the pointer, as both +the inertia and the momentum are reduced to the minimum quantity. The +subsidence of pressure resulting from explosives being about as sudden as +the creation of pressure, causes the pointer to move too rapidly for +correct ocular observation, on which account a static electric current is +employed, causing a stream of electric sparks to shoot off from the end +of the pointer, B, to the brass outer ring, M. The gauge is insulated for +that purpose by glass plate, S, which is secured concentrically to the +gauge proper and the ring, M. Binding posts for the electric wires are +provided at O and P, which wires are shown in Fig. 2. A spring clamp, N, +Fig. 2, enables the insertion of chemically prepared or other paper, +which lies against the inner side of brass rim, M, and held in place by +the clamp, N. The electric sparks above spoken of pierce the strip of +paper with small holes and colored marks. These holes, etc, show the +exact limits to which the pointer has traveled under pressure, and thus +an indelible record is kept by the electrical indications shown upon the +strip of paper. The paper can have the pressures corresponding to gauge +printed upon the same, when the holes are made prominent by holding the +paper to the light, exposing an exact indication of the pressures or +explosives operated with. + +The gases resulting from the explosives are injurious to the gauge +packings, etc., on which account the bore in gun, W, and the connecting +steel plug, B, are filled with fluid. A screw plug, U, enables the +insertion of the fluid, after first pushing an elastic wad of rubber, B, +or cork, in the bore near the inner wall of the gun, which wad will +prevent the escape of the fluid to the interior, and be sufficiently free +to prevent any interference with the pressures. The patentee and +manufacturer of this gauge is prepared to fill orders up to 50,000 lb. +per square inch. This gauge is made of the best steel, and is very +compact, the weight being inside of twenty-five pounds. + +The inventor has heretofore made mercury column gauges for gunpowder +pressures, which were too large for direct attachment to guns, but were +connected with special powder chambers to test the pressure, etc., of +confined explosives. The experience thus gained enabled the construction +of the instrument here shown, which is adapted to direct attachment to +the gun, making it as easy now to measure gunpowder pressures as it had +been, heretofore, to measure steam pressures. The effect of this movement +is to reduce the exaggerated statement of high pressures, obtained from +ordinary sporting powders; these have been accredited with pressures up +to 40,000 lb. per square inch, but they only really gave 22,000 lb. by +actual gauge measurement. Artillerists and ordnance officers have, in +this instrument, a true pulse of the internal pressures of the gun, of +inestimable value when determining the quantity of powder and the proper +weight of shot. These are important matters in ordnance practice. + +This gauge is a compact machine, designed to measure and indicate the +quick pressures resulting from gunpowder explosives and the slow +pressures of hydraulic force; the same mechanism used in both cases +permits the ready testing and examination of gauge under hydraulic +pressure, to determine its accuracy, for the more sudden pressure +occasioned by the use of gunpowder. + + * * * * * + + + + +IMPROVED PLAITING MACHINE. + + +The principal object the inventors of the machine we illustrate herewith +had in view in designing it was to arrange a mode of working the grip +motion positively, so that the cloth shall be received freely and without +strain or friction before or up to the very instant at which each fold is +completed, and shall then be seized and firmly held. In existing machines +there is not we believe, any arrangement for the accomplishment of this +purpose; it is true, the table upon which the cloth is folded is relieved +at the termination of the stroke of the plaiting knife, but the upper +gripper bar, against which the folds of cloth are pressed upon the return +of the table to its normal position, is stationary, being rigidly fixed +to the sides of the machine. One result of this rigidity is that the +cloth has to be forcibly thrust by the plaiting knife under the upper +gripper bar, and in consequence of the violence involved the fold just +made at the opposite end is dragged out from the grip, making a short +fold, and further, in the case of delicate finishes, giving rise to +damaged goods. Another result of this arrangement, when the cloth is not +pressed against the upper bar, is that it returns with the return stroke +of the plaiting knife, the grip not being made until the knife is clear +of the upper bar; thus the plaits or folds are made of irregular length. + +[Illustration: IMPROVED PLAITING MACHINE.] + +To remedy this and to prevent its occurrence, Messrs. A. Edmeston and +Sons, Manchester, in the plaiting machines they are now manufacturing +make the upper gripper bar movable as well as the table below. Referring +to the illustration, the upper gripper bars, A A, are capable of moving +about the center pins, B B, and when the machine is working are operated +in the following manner: + +Upon the shaft, C, which revolves in unison with the crank shaft working +the plaiting levers and knife, are placed two cams, D, one at each end, +inside the main frames. These cams engage with and work two escapement +levers or pallets, E E, upon which rest the feet of four rods, attached +one end to each of the upper gripper bars. Upon these four rods are +helical springs of sufficient strength to hold down, by means of the +grippers to which they are connected, the folds of cloth that have just +been made. The cam, D, is so shaped that when the advancing plaiting +knife and cloth reach the front edge of the gripper bar, the gripper is +raised from the table to admit them freely. The instant the end of the +stroke is reached the anchor pallet or lever, E, escapes from the cam, +and the gripper bar is suddenly forced on to the knife and cloth by the +springs before mentioned, securely retaining the piece in its position. +Simultaneously with the first of these motions the plaiting table itself +is lowered, and, when the plaiting knife reaches the end of its stroke, +is released by means of the levers and chains, F F, which are in +connection with the escapement pallets, E, and partake of their every +motion. These chains are so attached that they exert no effort upon the +table until the escapement lever is moved, thus permitting the plaiting +table to press upward against either one or both of the gripper bars with +the full force imparted to it by the weights and levers, G' G'. The +chains, furthermore, are also threaded over pulleys in such a manner that +they adjust themselves automatically to every position of the table and +to the different thicknesses which the folded cloth acquires. + +It will be obvious from this description that in plaiting there is no +more strain put upon the cloth in placing it under the grip than is +necessary to draw it over the table from the feed rollers. This feature +insures perfect immunity from the dragging out of grip, as already +described, and renders the machine very useful for finishers and +makers-up, as the delicacy with which the cloth is handled prevents any +damage being done to the finish of the lightest fabrics. Double cloth +can, of course, be plaited by it equally well, and the precision and +uniformity with which the cloth is plaited makes the machine thoroughly +reliable as a cloth measurer.--_Tex. Manfr._ + + * * * * * + + + + +SELF-ACTING SHUTTLE GUARD. + + +[Illustration: SELF-ACTING SHUTTLE GUARD.] + +The annexed illustration shows the essential parts of Hahlo and +Liebreich's improvement, the loom being now at work. The handrail, +shuttle race, and starting handle can be at once recognized, and the +shuttle guard will be seen in its proper position, which position it +rigidly retains as long as the loom is working, but on a stoppage the rod +swings back close underneath the handrail, and quite clear of the reed. +The mode in which this is accomplished we will endeavor to make clear. +The guard is connected to the starting lever by the arrangement shown, +consisting of a stud on the handle, on which, with the movement of the +slay, lever, a, slides. This lever, by means of another lever and a link, +is attached to the shuttle guard by the crank, b, which, by means of the +set screw in the boss, permits the shuttle guard to be adjusted in the +most convenient place. It will be observed that whenever the loom stops +working, whether it is stopped by hand or automatically, the hand lever +has to be moved, and this movement is communicated to the shuttle guard +by the mechanism just described, placing the guard rod beneath the hand +rail, and leaving the whole of the shuttle race free and unencumbered. +The act of starting the loom brings the guard again to the working +position without any extra act having to be performed by the weaver. The +action is entirely automatic, and the weaver has not anything to do that +she has not to do with the present unguarded looms. The arrangement +appeared to ourselves to be a very efficient one, and it has the merit +that the length of the guard can be made greater than the width of the +cloth, a further advantage that will be recognized by practical weavers. + + * * * * * + + + + +RULER AND TRIANGLE FOR HATCHING. + + +The instrument shown in the cut is the invention of Mr. Maginnis, and is +designed for producing equidistant hatchings. It consists of a short +ruler, A, and a triangle, B, supposed to be one of 45 deg., but which may be +of any angle. The triangle carries two stops, c c, while the ruler is +provided with a conical piece, D, which is slotted, and is held by a +screw. The play that occurs between this conical slide and the stops +varies according to the position of the former. + +[Illustration: RULER AND TRIANGLE FOR HATCHING.] + +The apparatus operates as follows: In the figure, the stop to the right +being in contact with the piece, D, a line is drawn along the right side +of the triangle. Then the ruler is made to slide along the triangle until +D touches the other stop, and then the triangle is slid along the ruler +until the stop to the right touches D again. In this position another +line is drawn, and so on. The position of the piece, D, between the stops +is regulated according to the fineness of the hatching to be +done.--_Chronique Industrielle_. + + * * * * * + + + + +THE DISTILLATION OF SEA WATER. + + +The supplying of the troops at Suakim and in the Soudan with water is one +of the most important items in the whole conduct of the Egyptian war. +Even in cold or temperate latitudes fresh water is a first necessity for +animal life; much more is this the case in the desert; and the wells in +the country forming the scene of our military operations form in +themselves valuable strategical points. Their supply, however, has to be +supplemented, and to do so artificial means and the aid of the engineer +have to be enlisted into this service. + +Many of our readers see notices from time to time in the newspapers about +this or that ship being employed, or at least her steam fittings, in +distilling water for the use of the troops; and although most of, if not +all, our readers are engineers, still it is no disparagement to some of +them to assume that they are more or less unfamiliar with sea water +distillation on the scale on which the process is now being carried on at +Suakim; and as the subject is of general interest, we give a short +description of the process. + +In a general sense, fresh water is obtained from sea water by simply +generating steam from the sea water, passing the said steam through a +surface condenser, and filtering the resulting water. The obtaining of +fresh water in this way has been in practice on board sea-going ships for +many years. It is supposed by some authorities on this subject that the +first time fresh water was thus obtained at sea was by an old captain of +a brig which ran short of water, and he cut up some pewter dishes into +strips, which he bent and soldered into a pipe. He, with the carpenter's +aid, fitted a wooden lid in one of the cooking boilers, and fixed one end +of his pipe in it. He next sawed a water cask in half, bored a hole in +the bottom of one half, and took his pipe through it, filling the space +round the pipe with sea water. Thus he extemporized a worm and still or +condenser. The distilled water, however, was scarcely drinkable. Not to +be beaten, however, the captain got some pieces of charred wood which he +put in the water, which so far improved it as to render it at all events +fit to sustain life, and our skipper brought his brig and her screw +safely to port. What suggested the use of charcoal to his mind history +does not tell. For many years past scarce any sea-going vessel leaves +port that is not fitted with a properly constructed distiller; and one +conspicuous advantage attending this practice is that each ship thus +fitted to the satisfaction of the Board of Trade inspector is allowed to +sail with only half the quantity of fresh water on board which she should +have if not provided with a distiller. The distiller and filter occupy +very much less space than that which would be occupied by the casks or +tanks of water otherwise required to be carried. + +Coming now a little to detail, sea water distillers are usually fitted in +connection with the winch and its boiler, which latter supplies the steam +both for distillation and to drive the engine working its circulating +pump. Smaller distillers are worked without a pump, the cooling water +merely passing through by gravitation. These smaller affairs again are of +two kinds, the one being mounted at one end of the cooking hearth, as in +outline sketch, which shows a two oven hearth with distiller at one end. +A is the supply pipe to admit air to aerate the water; B is the cock +where fresh water is drawn off; C is a pipe conveying cooling water to +the condenser E, placed on three little feet on top of the boiler, F, +whose steam rises up a central pipe to the dome top, where it expands out +and returns downward through a number of tubes about 1 in. diameter, in +which it is condensed, collected in a bottom chamber, and drawn off +through the cock, B. A distiller of this size would make about thirty +gallons of fresh water per day. Very frequently a distiller, such as is +shown in the sketch, is mounted separately, and placed near the winch or +donkey boiler, which supplies it with steam, the lower part, F, being +then used as a filter. The diameter of E is from 15 in. to 18 in., the +outer casing being either iron or copper. Another form of distiller is +one like the above, but larger, and having a small donkey engine and +circulating pump attached thereto. As a rule these distillers are +vertical, but larger apparatus are arranged horizontally. To give our +readers some general idea of size, weight, and produce of water, we may +say that a plain cylindrical distiller, mounted on a square filter case, +measuring 3 ft. 9 in. high, weighing 41/2 cwt., will distill twelve gallons +per hour. A larger size, measuring 6 ft. 2 in. high, and weighing about +23 cwt., will give 85 gallons; while a still larger one, measuring 7 ft. +high and weighing 32 cwt., yields 150 gallons. These have no pumps. When +an engine and pump are fitted, the weight is increased from about 80 per +cent. in the smaller to 50 per cent. in the larger sizes. An immense +advantage attends the use of those distillers that are combined with a +winch boiler. Of course, the chief use of the winch is while in dock; +some use is made of it at sea to do heavy pulling and hauling, to wash +decks, and in case of emergency the circulating pump is used as a fire +engine. Were it not, however, for the distiller, the winch boiler would +simply be idle lumber at sea. The distiller, however, finds useful +employment for it, and has also this excellent effect, that as steam is +pretty constantly kept up for the distiller, in the evil event of a fire +the boiler is ready to work at once. In horizontal types of distiller an +engine and pump are mounted on a cast iron casing as a bed, and in this +casing is placed a number of tubes through which the steam passes to be +condensed, the whole being simply a surface condenser with engine and +pump above. Another type is that of a small single-flued horizontal +boiler with combustion chamber and twenty or thirty return tubes--in +fact, the present high-pressure marine boiler on a small scale. A boiler +of this sort, measuring 4 ft. to 5 ft. long, 3 ft. 9 in. to 4 ft. 6 in. +diameter, would have a horizontal donkey engine on a bed at its side, and +at the end of the engine a vertical cylindrical condenser. + +[Illustration] + +Few have done more, perhaps none so much, as Dr. Normandy to make sea +water distillation not only a success as a source of water supply, but +also to supply it at a minimum cost for fuel. He by a peculiar +arrangement of pipes embodied something of the regenerative system in his +apparatus, using the heat taken from one lot of steam to generate more, +and again the heat from this he used over again. The defect of his older +arrangements was undue complexity and consequent trouble to keep in +order. + +As can be well imagined, the distillers in use at Suakim are on a much +more colossal scale, and owing to the now almost universal use of surface +condensers in ocean steamers, no great difficulty ought to attend the +adaptation of the boilers and condensers of one of our transports. One of +these full-powered steamers will indicate, say, 5,000 horse-power, and +assuming her engines to use 25 lb. of steam per indicated horse-power, or +21/4 gallons, she could distill some 12,000 gallons of water per hour. As +no appreciable pressure of steam need be maintained, the boilers would +suffer little from deposit, especially if regularly blown out. Hard +firing need not be resorted to; indeed, it would be injudicious, as, of +course, priming must be carefully guarded against. Of course, the salt +water distilled will affect the working, not exactly of the distillers, +but of the boilers. If the water in the harbor, as is not improbable, is +muddy, some method of filtering it before pumping it into the boilers +ought, if at all practicable, to be resorted to, for the twofold reason +of preserving the boiler plates from muddy deposit, and also to prevent +priming, which would certainly ensue from the use of muddy water. No +doubt the medical staff take care that the distilled water is alike +thoroughly aerated and efficiently filtered. The most successful method +of aerating is, we believe, to cause the current of steam as it enters +the condenser to suck in air by induced current along with it. The +filtering ought not to present any difficulty, as at all events sand +enough can be had. Charcoal, however, is another affair, and all +distilled water ought to be brought into contact with this substance. + +Simple, however, as such an arrangement as this appears to be, practical +difficulties, which it is _said_ are insurmountable, stand in the way of +its adoption, and the distilled water produced for Egypt is made in +special apparatus, and various forms of condenser are employed, made +under various patents. The principle involved is, however, in all cases +the same. Steam is generated in one of the ships' boilers, and condensed, +filtered, and aerated in a special apparatus. The great objection to the +use of the ordinary surface condenser is that the main engines would, in +the majority of cases, have to be kept going, in order to pump the +distilled water out of the condenser, and to supply circulating water. +But it is easy to see that if engineers thought proper, this difficulty +could be readily got over. Separate circulating pumps, usually +centrifugal, are now freely used, and the addition of a special pump for +lifting the condensed water presents no difficulty whatever. While the +main engines are running, the withdrawal of much condensed water would +no doubt risk the safety of the boiler; but in the case of so-called +"distilling" ships, there need be no trouble incurred on this +score.--_The Engineer_. + + * * * * * + + + + +AIDS TO CORRECT EXPOSURE ON PHOTOGRAPHIC PLATES. + +[Footnote: We take from the Br. Jour. of Photo. the following interesting +paper read by W. Goodwin before the Glasgow and West of Scotland Amateur +Association.] + + +With good plates, and intelligent development, a practiced photographer +may within certain limits correct the effects of an over or under +exposure; but you have all, doubtless, found out that there is a correct +exposure, and that you cannot trespass very far on either side of it +without sacrificing something in the resulting negative. + + MR. W.K. BURTON'S TABLE OF COMPARATIVE EXPOSURES +------------+--------------------+-------------------+------------------------- + | | Badly lighted| Portraits in bright + | | interiors,| diffused light +Aperture | +------------+ up | out of doors. +calculated | Landscape with | Fairly | to | / +on the | heavy foliage in | lighted | | / Portraits in +standard | foreground. | interiors | | / studio light +system +------+-------+ +------+ | | | / +of the | Sea |Open | | Under| | | | / Portraits +Photographic| and |land- | |trees,| | | | | in ordinary +Society. | sky. | scape.| |up to | | | | | room. +------------+------+-------+-----+------+-----+------+------+-----+------ + | sec | sec | sec | m s | m s| h m | sec | m s| m s +No. 1, | 1/160| 1/50 | 1/8 | 0 10 | 0 10| 0 2 | 1/6 | 0 1| 0 4 +or f/4 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 2, | 1/80 | 1/25 | 1/4 | 0 20 | 0 20| 0 4 | 1/3 | 0 2| 0 8 +or f/5.657 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 4, | 1/40 | 1/12 | 1/2 | 0 40 | 0 40| 0 8 | 2/3 | 0 4| 0 16 +or f/8 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 8, | 1/20 | 1/6 | 1 | 1 20 | 1 20| 0 16 | 1-1/3| 0 8| 0 32 +or f/11.314 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 16, | 1/10 | 1/3 | 2 | 2 40 | 2 40| 0 32 | 2-2/3| 0 16| 1 4 +or f/16 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 32, | 1/5 | 2/3 | 4 | 5 20 | 5 20| 1 4 | 5-1/3| 0 32| 2 8 +or f/22.627 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 64, | 2/5 | 1-1/3 | 8 |10 40 |10 40| 2 8 |10-1/2| 1 4| 4 15 +or f/32 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 128, | 4/5 | 2-2/3 | 16 |21 0 |21 0| 4 15 | 21 | 2 8| 8 30 +or f/45.255 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ +No. 256, |1-1/2 | 5-1/2 | 32 |42 0 |42 0| 8 30 | 42 | 4 15|17 0 +or f/64 | | | | | | | | | +------------+------+-------+-----+------+-----+------+------+-----+------ + +The estimation of this correct exposure is probably the greatest +difficulty in photography, and it is particularly discouraging to find +plate after plate useless because the guess has been wide of the mark. +There are some here to-night who have spoiled so many plates that at last +they are prepared by experience for almost any contingency, and to those +I nave very little to say; but there are also many who are still in their +troubles, and I propose to tell them how the amount of guesswork required +may be reduced to a minimum. + +The factors which govern exposure are: the subject of the picture, the +lens and its aperture, the rapidity of the plate, and last, but not by +any means least, the quality of the light by which the work is to be +done. + +Let us consider each of these separately, and see if we cannot reduce any +of them to rule. In this respect the subject will be found somewhat +intractable. Scarcely two subjects will be found to send exactly the same +amount of light through the lens. However, a broad classification may be +made, and this has been done by Mr. Burton in his Table of Comparative +Exposures. A glance at this table will show how greatly the character of +the view may influence the time of exposure. Thus, with full aperture of +a rapid symmetrical, the exposure for open landscape is given as +one-twelfth of a second; when heavy foliage appears in the foreground, +half a second will be required; while, under trees, as much as forty +seconds may be needed. + +The first aid I have to suggest is the use of such a table as Mr. +Burton's. Before we do anything more in this direction, we must consider +the influence of the lens and its diaphragms. In theory the single +landscape lens is more rapid than the doublet of equal aperture, but the +difference is so little that it may be disregarded in practice, and my +remarks will apply to both. + +The rapidity of a lens depends mainly on its aperture and its focal +length. Thus a lens of twelve inches focus will require four times the +exposure of a six inch, with an equal sized diaphragm, and a quarter inch +diaphragm will require four times the exposure of a half inch when used +in the same lens. + +The Photographic Society of Great Britain have recommended that the +diaphragms of all lenses should bear such relation to the focal length +that each should require exactly double the exposure of the next smaller. +Now, if we turn again to Mr. Burton's table, we shall find that it is +constructed on this principle, and that each stop is numbered so as to +show its exposure. Obviously, the most sensible thing would be to get a +set of stops made to correspond with this arrangement, but we will see +how we can construct a table for stops of any size. + +First, if possible, find the equivalent focus of your lens. If it is made +by a known maker, you will find it in his price list, and if not, you may +calculate it for yourself by the rules given in the various text books, +provided you have a camera of pretty long focus. However, it will be near +enough for our purpose if you get a sharp image of the sun on a piece of +paper, and while you hold lens and paper, get some one to measure the +distance from the paper to the diaphragm aperture, or, in the case of a +single lens, to the center of the lens. Note down this focal length, and +proceed to measure your diaphragms in sixteenths of an inch. + +Then, with pen and paper, proceed to divide the diameter of each stop +into the focus, and state the result as a fraction of the focus, thus +f/8. For example, a Ross half plate rapid symmetrical has a focal length +of 71/2 in.; for convenience reduce this to sixteenths=120. A diaphragm +measuring seven sixteenths will give the fraction f/17. Now let us see if +any of these stops correspond with Mr. Burton's. The first two in his +table will only be found in portrait lenses, but we shall probably find +one to correspond with the third, if we are using a doublet lens; with a +single lens we won't find any so large. Having picked out those that +correspond, and filled in the exposure for them, we have now to deal with +the odd sizes. Here is one, f/27, which is just half way between No. 16 +and No. 32, but a moment's thought will show that as the exposure +increases as the square of the diameter, it won't do to take the exposure +half way between the two. + +We have another factor to consider now: that is, the rapidity of the +plate. If you use plates by a maker who has a name to sustain, you may be +pretty confident that they are of fairly uniform rapidity, so after you +have got into the way of working any particular brand, the best thing you +can do is to stick to it. The exposures in our table are for plates of +medium rapidity in good spring light. In my own experience I find that +they just suit "thirty times" plates, or fifteen on the sensitometer; but +then I like a full exposure with slow development, and I know that others +find these exposures just right for "twenty times" plates developed in +the usual way. The most rapid plates in the market will not be overdone +with half the given exposures. It must always be borne in mind that an +error of a fraction of a second in either direction may be corrected in +development, and it is impossible to make a very serious error if you +refer to the table. + +We come now to the light. If you depend on the eye entirely in judging +the quality of the light, it will sometimes play you tricks. The rays +which are most active on the plates are those which have the least effect +on the eye. We can, however, by chemical means arrive at an exact +estimate of the active power, and for this purpose an actinometer is +used. This is simply an arrangement whereby a piece of sensitized paper +is exposed and allowed to darken to a standard tint, and by the time it +takes to reach that tint the value of the light is judged. Capt. Abney +has, however, pointed out that ordinary sensitized paper is not suitable +for bromide plates, since there are conditions of light in which the +plates will be fairly rapid while the paper will be very slow. He gives a +formula for a bromide paper, which is treated with tannin in order to +absorb the bromine set free during exposure, otherwise the darkening +would be very slight. I used this paper for a while, but found it rather +slow. The tannin also turned brown on keeping for a week or so. I then +made some more, substituting for tannin potassium _nitrite_ (not +nitrate), which is colorless. This was an improvement, but still it was +just slow enough. + +However, noticing in Capt. Abney's article the statement that the bromide +of silver should be as nearly as possible in the same state in the paper +as in the plate, I thought "Why not Morgan's paper?" This, of course, is +just bromide emulsion on paper, and if, as I suspect from its color, it +contains a trace of iodide, why, so do most commercial plates. A sheet of +this paper cut into strips, soaked for ten minutes in a fifteen-grain +solution of potassium nitrite, and dried, gives a sensitive paper which +darkens with great rapidity to a good deep tint, and keeps indefinitely. +Here is some prepared last summer, which is still quite good. To use this +paper make a little box so that a little roll of it can be stored in one +end, and drawn forward as required beneath a piece of glass. + +Bearing in mind that your table of exposures is calculated for the best +spring light, go to the country some bright day next month with +note-book, actinometer, and the necessary appliances for exposing a few +plates. Select, say, an open landscape, and use your smallest stop. When +all ready to expose, get out your actinometer and expose it to the +reflected light of the sky for ten seconds (if the sun is shining, turn +your back to it, and keep the actinometer in your own shadow); then put +it in your pocket, expose a plate according to your table, and in case +the light or plate should not be just in accordance with the conditions +under which the table was prepared, expose other two plates, one a little +less and one a little more than that first exposed. Then note down +everything you have done--kind of view, stop, speed of plate, exposure of +each plate, and length of exposure of actinometer. + +When you get home, the first thing to do is to get hold of a paint box +and paint the underside of the glass of your actinometer to match the +darkened paper. Do this by gas light. Then scrape away a little of the +paint, so as to let a strip of the paper be seen below it. After this +develop your three plates with a developer of normal strength, and see +which is best. If you have chosen a really bright spring day, and are +using plates of medium rapidity, you will most likely find that exposed +according to the table just about right. + +Now let us see how we can use these aids in our field work. We have +ascertained the correct exposure with a given stop on one class of view, +with light of a given quality, but now suppose all these conditions +altered. Let the view have heavy foliage coming close up to the camera, +the stop be a size larger than that used in our first experiment, and the +day rather dull. The table tells us what the exposure would be with this +stop on this view, on a bright day; and if the actinometer take twenty +seconds to reach the painted tint, then we must double the exposure given +in the table. + +You may sometimes find that the actinometer indicates a very different +exposure from what the eye would lead you to expect. For instance, one +day last September I went to Bothwell Castle, to get a picture I knew of +in the grounds. It was one of those strange yellow days we had then, and +the sun, though shining with all his might, was apparently shining +through orange glass. The actinometer indicated an exposure of thirty +seconds where in good light one would be right. I was rather incredulous. +Thirty seconds in broad sunshine! However, I gave this exposure, but for +my own satisfaction I gave another plate fifteen seconds only. + +On developing, the latter was hopelessly underexposed while that having +thirty seconds gave a negative which furnished one of my exhibition +pictures. + +I have shown you how to reduce the quality of the light to a certainty, +also how to reduce to rule the exposure with different lenses and stops +on certain classes of subjects, and it remains with you only to guess +correctly to what class the view you wish to take belongs; I can assure +you from my own experience that there is enough uncertainty about that +point to prevent good negatives ever becoming monotonous. + +The only aid I can suggest in this case is the continual use of a +note-book. Note every plate you expose, and when you have a failure be +careful to record the fact, and you will gradually find these accumulated +notes becoming a great help in cases of doubt. One hint I can give to +beginners is that a great number of the pictures to be met with in this +part of the country are intermediate between "Open Landscape" and +"Landscape with heavy foliage in foreground;" and it is scarcely needful +to say that if you are in doubt, let the exposure be rather too much than +too little; you _may_ make a negative of an overexposed plate, but never +of an underexposed one. + + * * * * * + + + + +ISOCHROMATIC PHOTOGRAPHY. + +[Footnote: Read at the stated meeting of the Franklin Institute, March +18, 1885.] + +By FRED. E. IVES. + + +It is well known that the ordinary photographic processes do not +reproduce colors in the true proportion of their brightness. Violet and +blue photograph too light; green, yellow, orange and red, too dark. For a +long time it was believed to be impossible to remedy this defect; and +even when it became known that bromide of silver could be made more +sensitive to yellow and red by staining it with certain dyes, the subject +received very little attention, because it was also known that the +increase of sensitiveness was too slight to be of practical value in +commercial photography. + +Dr. H.W. Vogel, who was one of the first, though not the first, to devote +attention to this subject, announced, in 1873, that he had succeeded in +making a yellow object photograph lighter than a blue or violet one, by +using a silver-bromide plate stained with coraline, and exposed through a +yellow glass. The plate showed no increased sensitiveness to red, and the +experiment, although of considerable scientific interest, did not +indicate a practically useful process. + +In the spring of 1878 I became interested in this subject, and tried to +discover a method of producing plates which should be sensitive to all +colors, and capable of reproducing them in the true proportion of their +brightness. I commenced by trying nearly all the color sensitizers which +had already been suggested, in order to learn which was the best, and +then, if possible, _why_ it was the best, as a guide to further research. +Chlorophyl was the only thing I tried which was sufficiently sensitive to +red to offer any encouragement in that direction; but the solution which +I obtained was weak and unstable, and far from being a satisfactory color +sensitizer. Hoping to obtain a better solution with which to continue my +experiments, I made extracts from many kinds of leaves, and found that a +solution from blue myrtle leaves looked better and kept better than any +other, and when it was applied to the silver-bromide plates they became +remarkably sensitive, not only to all shades of red, but also to orange, +yellow, and green. By placing in front of the lens a color-screen +consisting of a small glass tank containing a weak solution of bichromate +of potash, to cut off part of the blue and violet light, I obtained, with +these chlorophyl plates, the first photographs in which all colors were +reproduced in the true proportions of their brightness. But my chief +desire at that time was to realize a method of producing from any object +in colors a set of three negatives, in one of which the shadows should +represent the blue of the original, in another the yellow, and in another +the red, in such a manner that transparent pigment prints from these +negatives--blue, yellow, and red--would, when superimposed on a white +surface, represent not only the lights and shadows, but also the colors +of the object. This had already been attempted by others, who failed +because their plates were not sufficiently sensitive to red and yellow. + +Having succeeded perfectly in my undertakings, I published my discovery +in 1879,[1] explaining how to prepare and use the chlorophyl plates, in +connection with the yellow screen, for the purpose of securing correct +photographs of colored objects.[2] + +[Footnote 1: _Philadelphia Photographer_, December, 1879, p. 365.] + +[Footnote 2: I intended this publication to be a very full and explicit +one, and it was sufficiently so to be perfectly understood by most who +saw it; but some may think I did not sufficiently emphasize the +importance of using the particular kind of chlorophyl which I mentioned. +In a brief communication to the editor of the _Photo. News_, in 1883, I +described some experiments with eosine as a color sensitizer, and then +called attention to the superiority of blue-myrtle chlorophyl for this +purpose, stating that I had not been able to secure such results with any +other kind of chlorophyl, and that a fresh solution from fresh leaves +must be used to secure the greatest possible degree of sensitiveness. See +_Photo. News_, Nov. 1883, p. 747.] + +So far as I know, nobody tried the process. Nearly five years later Dr. +Vogel announced that, after eleven years of investigation, he had at last +realized a successful process of this character, and that this new +process of his was the "solution of a problem that had long been +encompassed with difficulty." This publication attracted a great deal of +attention, and gave me occasion to again call attention to my process,[3] +and point out that it was not only the first practical solution of this +problem, but the only truly isochromatic process ever discovered. Dr. +Vogel's new process was not only no better in any respect, but the plates +were insensitive to scarlet and ruby-red, and therefore would not +photograph all colors in the true proportion of their brightness. + +[Footnote 3: _Photo. News_, London, September 5, 1884, p. 566, and _Year +Book of Photography_ for 1885, p. 111.] + +My method consists in treating ordinary collodio-bromide emulsion plates +with blue myrtle chlorophyl solution, exposing them through the yellow +screen, and then developing them in the usual manner. The emulsion which +I have employed is made with an excess of nitrate of silver, which is +afterward neutralized by the addition of chloride of cobalt; it is known +as Newton's emulsion. I now prepare the chlorophyl from fresh blue myrtle +leaves, by cutting them up fine, covering with pure alcohol, and heating +moderately hot; the leaves are left in the solution, and some zinc powder +is added, which helps to keep the chlorophyl from spoiling. I have a +bottle of this solution which was prepared about six months ago, and now +appears to be as good as when first made.[4] A glass plate is flowed with +the emulsion, and as soon as it has set, the chlorophyl solution is +applied for a few seconds, after which the plate is washed in pure water +until smooth, when it is ready for exposure. + +[Footnote 4: I originally recommended chlorophyl extracted from dried +leaves, because I had not yet learned how to preserve the solution for +more than a few weeks; and at some seasons it would be difficult, if not +impossible, to obtain fresh leaves. The tea organifier which I +recommended is also a color sensitizer, and when it is used in connection +with the chlorophyl from dried leaves the plates are as sensitive to red +as can be safely prepared and developed in the light of an ordinary +photographic "dark-room." Plates prepared with chlorophyl from fresh +leaves do not require treatment with the tea organifier to secure this +degree of sensitiveness. Recently I have used the tea organifier and some +other sensitizers, in connection with the solution from _fresh_ +myrtle-leaves, and in this way have produced plates having such an +exalted color sensitiveness as to be unmanageable in ordinary "dark-room" +light. Possibly, such plates might be prepared and developed in total +darkness, by the aid of suitable mechanical contrivances, but I am not +sure that they would work clear even then, because they appear to be +sensitive to heat as well as to light.] + +My color-screen consists of a small plate-glass tank, having a space of +3/16 of of an inch between the glass, filled with a solution of +bichromate of potash about one grain strong. I place the tank in front of +the lens, in contact with the lens-mount. The advantage of this tank and +solution is that it can be more easily obtained than yellow plate glass, +and the color can be adjusted to meet any requirement. + +The plates require about three times as much exposure through the yellow +screen as without it, and may be developed with the ordinary alkaline +pyro-developer. + +[Illustration: IVES' PROCESS OF ISOCHROMATIC PHOTOGRAPHY.] + +In order to illustrate the value of this process, I made two photographs +of a highly-colored chromo-lithograph, representing a lady with a bright +scarlet hat and purple feather, a yellow-brown cape and a dark-blue +dress. One, by the ordinary process, represents the blue as lighter than +the yellow-brown, the bright scarlet hat as black, and the purple feather +as nearly white. The other, by the chlorophyl process, reproduces all +colors in nearly the true proportion of their brightness, but with a +slight exaggeration of contrast produced purposely by using a too-strong +color solution in the small tank. + +I also made two landscape photographs, one by the ordinary process, and +the other by the chlorophyl process, exposing them simultaneously. In the +ordinary photograph, distant hills are lost through overexposure, yet the +foreground seems underexposed, and yellow straw-stacks and bright autumn +leaves appear black. In the chlorophyl photograph, the distant hills are +not overexposed, nor is the foreground underexposed; the yellow +straw-stacks appear nearly white, and bright autumn leaves contrast +strongly with the dark green about them. + +To test the relative color-sensitiveness of plain emulsion plates, plates +stained with eosine, and plates stained with the blue-myrtle chlorophyl, +I exposed one of each kind through the same yellow screen, giving each +five minutes exposure, on the same piece of copy, which was the +chromo-lithograph already described. The plain emulsion plate showed only +the high lights of the picture, after prolonged development. The eosine +plate was underexposed, but brought up everything fairly well except the +scarlet hat, which came up like black. The chlorophyl plate was +overexposed, brought out all colors better than the eosine plate, and +gave full value to the bright scarlet of the hat, the detail in which was +beautifully rendered. + +Dr. Vogel advanced the theory that silver-bromide is insensitive to +yellow and red, because it reflects or transmits those colors; and that +it becomes sensitive when stained, because of the optical properties of +the dyes. He afterward admitted that only such dyes as are capable of +entering into chemical combination with the silver-bromide proved capable +of increasing its sensitiveness to color, but he held to the theory that +the optical properties of the compound were the cause of its +color-sensitiveness. + +I have shown that the color-sensitiveness can be produced by treatment +with an organic compound which has none of the optical properties +characteristic of dyes; and that chlorophyl, which absorbs only red +light, greatly increases the sensitiveness also to yellow and green. +There is, therefore, good reason to doubt if the color-sensitiveness is +ever due to the optical properties of the dye or combination. + +Attempts have been made to produce isochromatic gelatine dry plates +which, while many times more sensitive to white light than my chlorophyl +plates, shall also show the same relative color-sensitiveness. Such +plates would be very valuable but for one fact: it would be necessary to +prepare and develop them in almost total darkness. Gelatine bromide dry +plates extremely sensitive to yellow, but _comparatively insensitive to +red_, might be used to advantage in portrait and instantaneous +photography, because they could be safely prepared and developed in red +light; but when truly isochromatic photographs are required, the time of +exposure must be regulated to suit the degree of sensitiveness to red, +which cannot safely be made greater than I have realized with my +chlorophyl process. + + * * * * * + + + + +DISTORTION FROM EXPANSION OF THE PAPER IN PHOTOGRAPHY. + + +The effect of the unequal expansion of paper, when wetted, in causing +distortion of the photographic image impressed upon it, has, in the case +of ordinary photographs upon albumenized paper, been well recognized; but +the extent to which such distortion may exist under different treatment +is worthy of some special consideration, particularly with reference to +the method of printing upon gelatinized paper, which has been thought by +some likely to supersede the method now usually employed with albumenized +paper. + +When a print upon the ordinary photographic (albumen) paper is wetted, +the fiber expands more in one direction than in the other, so that the +print becomes unequally enlarged, very slightly in one and much more so +in the other way of the paper. When the paper is dried without any strain +being put upon it, the fibers regain very nearly their original +dimensions and position, so that the distortion which has existed in the +wet condition nearly disappears. + +If the photograph is cemented, while in the expanded condition, upon a +rigid surface, the distortion then existing is fixed, and rendered +permanent. Such a cementation or method of mounting is that which has +been generally adopted, and the consequence has been that every now and +then complaints have justly been made of the untruthfulness--owing to +this particular distortion--of photographs; productions whose chief merit +has often been asserted to consist in their absolute truthfulness. This +distortion is very manifest when, in a set of portraits, some of the +prints happen to have been made in one direction of the paper, and others +with the long grain the other way. I have known a case where a proof +happened to increase the face in width, and all the other prints +increased it in length. Of course, neither was correct, but the proof had +been accepted and liked, and the remainder of the set had to be reprinted +with the grain of the paper running in the same direction as that in the +first one which had been supplied. + +Another evil arising from mounting prints while expanded with moisture +is, that in drying the contraction of the paper pulls round the card into +a curved form and although by rolling this curvature may be temporarily +got rid of, the fiber of the paper is in a strained condition, and the +bent state of the mount is, sooner or later, renewed thereby. + +To remedy these evils it has been proposed to mount the print when dry, +by forcible pressure against a slightly damped card, the back of the +print having been previously coated with a cement and dried. This plan +is, to a great extent, successful; but that it does not give absolute +immunity from distortion is, I think, evident from the following +consideration. The prints, after being mounted a few days, will show a +certain tendency to curl inward. This curling, I take it, is a measure of +the strain upon the print, produced by the more complete return to its +original dimensions of the paper photograph. Probably it would be well to +keep the prints a few days after drying, or to subject them to +alternations of damp and dryness, in order to facilitate this complete +return before being placed upon the card. The evil of distortion is, +however, very slight--perhaps imperceptible--compared with that existing +when the prints are mounted wet. I may mention, _en passant_, that I have +found gum much more satisfactory as a mountant than starch paste in what +is known as the "dry mounting" system. + +The paper which has recently been introduced for producing prints by +development upon a gelatine surface does not generally, when dried in the +usual way, give so good or so brilliant a surface as that of albumenized +paper; but on the other hand it is very easy with it to obtain what is +called an enamel surface, by simply allowing it to dry in contact with a +prepared surface of glass. This method of finishing has therefore been +much recommended and adopted, but without consideration of the effect of +distortion in connection with it. In an ordinary photograph the print is +mounted damp, but in the case of a print squeegeed on to the glass, the +paper is saturated and thoroughly swollen, and the use of the squeegee +strains it out to its fullest extent. By drying in the position in which +it has been held by contact with the glass, the distortion becomes fixed, +and if the print is mounted while in this state the distortion is made +permanent. How long the strain and distortion remain in an unmounted +print, and whether by time and alternations of moisture and dryness the +strain would be lost, and if so, whether the brilliant enamel surface +would go at the same time, are questions worthy of further investigation +and discussion. + +For mounting prints upon developed gelatine paper, it has been +recommended to cement the edges only, so as to leave the greater part of +the print with its enamel surface. This plan is unsatisfactory, for two +reasons, besides the objection on the ground of distortion. There is a +rough-looking margin which spoils the continuity of appearance, +especially (as in the specimens I have seen) where the line of cement is +not kept at an exact width, but encroaches here and there. + +Secondly, the print, from not being attached to the mount all over, is +apt, especially when in a large size, to be somewhat wavy and wanting in +flatness. Another plan recommended, as giving a surface resembling +albumen paper, is to paste the back of the print without moistening the +surface, and so mount. Some prints that have been shown thus treated had +so strongly curled the cards upon which they were mounted that it is +evident there was considerable strain and consequent distortion. + +A third plan recommended is to paste the back of the print while in +contact with the glass upon which it has to dry; and, when dried, to +mount by passing through a rolling press with a damped card. This plan +looks, at first sight, like that recommended for albumen paper, and +called "dry" mounting. Consideration, however, will show that there is a +radical difference. In the case of the albumen paper the print has been +dried without strain, and therefore but little change is to be looked +for, while the print dried in contact with glass is strained to the +utmost, causing present distortion and future curling of the mount. +Perhaps the evil of distortion caused by enameling may be reduced to a +minimum by soaking the print in alcohol previous to laying it upon the +glass. + +Since the distortion of the photograph arises from the unequal expansion +of the paper when wet, it becomes a question whether something may not be +done in the selection of the paper itself. It may be that some makes vary +much less than others in the "length against width" extension of the +surface by wetting. It must be remembered that for gelatine emulsion we +are not nearly so limited in the selection of paper as when it is +required to be albumenized. In the latter case the image is in the paper, +whereas with gelatine the image is contained in the surface coating. I +may mention that the best plain, i.e., not enameled, but resembling that +of ordinary albumen paper, surface that I have seen upon gelatine paper +was upon some foreign post that I had obtained for another purpose. The +emulsion employed was that described by Mr. J.B.B. Wellington, and this +gentleman agreed with me in attributing the superiority of the surface +obtained to the fine quality of the paper upon which the emulsion had +been coated. Some commercial samples appear to be coated upon paper of +somewhat coarse texture. This does not show when the print is enameled. + +The unequal expansion of paper is a subject of interest, not only in +connection with gelatine paper for development, but with various +photographic processes. In making carbon transparencies for instance, the +gelatine film which is squeegeed against the glass necessarily takes its +dimensions from the paper to which it is attached, and if that be +expanded more in the one direction than another, the transparency is +similarly deformed; and so, of course, is any negative, enlarged or +otherwise, produced in the camera therefrom. A reproduced negative by +contact printing may either have the distortion due to expansion of the +paper bearing the gelatine film removed or doubled, according to the +direction in which the paper is used for the new negative.--_W.E. +Debenham, in Br. Jour. of Photography_. + + * * * * * + + + + +MEASURING THE THICKNESS OF BOILER PLATES. + + +An ingenious process for determining the thickness of iron plates in +boilers, or places where they cannot otherwise be measured without +cutting them, has been invented by M. Lebasteur. He spreads upon the +plate the thickness of which he desires to find, and also upon a piece of +sheet iron of known thickness, a layer of tallow about 0.01 inch thick. +He then applies to each, for the same length of time, a small object, +such as a surgeon's cauterizing instrument, heated as nearly as possible +to a constant temperature. The tallow melts, and as in the thicker plate +the heat of the cautery is conducted away more rapidly, while in the thin +plate the heat is less freely conducted away, and the tallow is +consequently melted over a large area, the diameters of the circles of +bare metal around the heated point, bounded after cooling by a little +ridge of tallow, will be to each other inversely as the thickness of the +plates. The process is stated to have given in the inventor's hands, +results of great accuracy. + + * * * * * + + + + +GROUPS OF STATUARY FOR THE PEDIMENT OF THE HOUSE OF PARLIAMENT IN +VIENNA. + + +The pediment of the central pavilion and the two side pavilions of the +new House of Parliament, at Vienna, are to be ornamented with groups of +statuary. The group in the middle pediment represents the granting of the +constitution by the Emperor Francis Joseph, and was executed by Professor +Helmer. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--SCIENCE +AND LITERATURE. (GROUP TO THE LEFT.)] + +The pediment of the left wing is ornamented by a group representing +Justice, and the pediment of the right wing by a group representing the +Home Government. + +Johannes Benk, the well known Austrian sculptor, designed and executed +the last mentioned group. The two figures at the left hand end of this +group represent Science and Literature, and those at the right hand end, +Industry and Commerce. The entire group consists of nine figures, the +middle figure being seated and the rest standing, sitting, and lying, as +the space in the pediment allows. + +A seated female figure studying a papyrus roll represents Science, and +the adjacent female figure, resting one arm on the figure representing +Science, and the other, on a lyre, represents Literature or Poetry. + +Industry is represented by a strong and powerful woman holding a hammer, +and the figure of Mercury and the prow of a vessel represent Commerce. + +[Illustration: STATUARY FOR THE VIENNA HOUSE OF PARLIAMENT.--INDUSTRY +AND COMMERCE. (GROUP TO THE RIGHT.)] + +The modulation and formation of each figure conform strictly to Grecian +models, as does also the entire arrangement of the figures in the group; +and yet there is much of modern life in the figures, especially in the +faces, in which the stereotyped Grecian profile has not been adopted. The +attitudes of the figures are also freer and more easy than those of the +Grecian period.--_Illustrirte Zeitung_. + + * * * * * + + + + +ON THE FRITTS SELENIUM CELLS AND BATTERIES. + +[Footnote: Paper read before the American Association for the Advancement +of Science, at Philadelphia, Sept, 5, 1884.] + +By C.E. FRITTS, 42 Nassau St., New York, N.Y. + + +In all previous cells, so far as I am aware, the two portions or parts of +the selenium at which the current enters and leaves it have been in +substantially the same electrical state or condition. Furthermore, the +paths of the current and of the light have been transverse to each other, +so that the two forces partially neutralize each other in their action +upon the selenium. Lastly, the current flows through not only the surface +layer, which is acted upon by the light, but also the portion which is +underneath, and not affected thereby, and which therefore detracts from +the actual effect of the light upon the selenium at the surface. + +My form of cell is a radical departure from all previous methods of +employing selenium, in all of these respects. In the first place, I form +the selenium in very thin plates, and polarize them, so that the +opposite faces have different electrical states or properties. This I do +by melting it upon a plate of metal with which it will form a chemical +combination, sufficient, at least, to cause the selenium to adhere and +make a good electrical connection with it. The other surface of the +selenium is not so united or combined, but is left in a free state, and a +conductor is subsequently applied over it by simple contact or pressure. + +During the process of melting and crystallizing, the selenium is +compressed between the metal plate upon which it is melted and another +plate of steel or other substance with which it will not combine. Thus by +the simultaneous application and action of heat, pressure, chemical +affinity, and crystallization, it is formed into a sheet of granular +selenium, uniformly polarized throughout, and having its two surfaces in +opposite phases as regards its molecular arrangement. The non-adherent +plate being removed after the cell has become cool, I then cover that +surface with a _transparent conductor of electricity_, which may be a +thin film of gold leaf. Platinum, silver, or other suitable material may +also be employed. The whole surface of the selenium is therefore covered +with a good electrical conductor, yet is practically bare to the light, +which passes through the conductor to the selenium underneath.[5] My +standard size of cell has about two by two and a half inches of surface, +with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can, +of course, be made of any size or form. A great advantage of this +arrangement consists in the fact that it enables me to apply the current +and the light to the selenium in the same plane or general direction, +instead of transversely to each other as heretofore done, so that I can +cause the two influences to either coincide in direction and action, or +to act upon opposite faces of the selenium and oppose each other, +according to the effect desired. + +[Footnote 5: The method of constructing the cells was described in the +SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.] + +By virtue of the process and arrangement described, my cells have a +number of remarkable properties, among which are the following: + +1. _Their sensitiveness to light_ is much greater than ever before known. +The most sensitive cell ever produced, previous to my investigations, was +one made by Dr. Werner Siemens, which was 14.8 times as conductive in +sunlight as in dark. In table A, I give results obtained from a number of +my cells. + +It will be observed that I have produced one cell which was 337.5 times +as conductive in hazy sunlight as in dark. The tremendous change of +resistance involved in the expression "337.5 times" may perhaps be more +fully realized by saying that 99.704 _per cent_. of the resistance had +disappeared temporarily, under the joint action of light and electricity, +so that there remained _less than 3/10 of 1 per cent_. of the original +resistance of the selenium in dark. + +In order to obtain these high results, the cells must be protected from +light when not in use. The resistance is first measured while the cell is +still in total darkness. It is then exposed to sunlight and again +measured. It is also necessary to send the current in at the gold +electrode or face, as the cell is much less sensitive to light when the +light acts upon one surface of the selenium and the current enters at the +opposite surface. When the two influences, the light and the current, act +through the gold, in conjunction, their forces are united; and, as every +atom of the selenium is affected by the light, owing to the extreme +thinness of the plate, we have the full effect shown in the measurements. + + TABLE A. + + SENSITIVENESS TO LIGHT. + +----------------------------------------------------------------- +Selenium | Battery | Resistance in | Resistance in | + cell. | power. | dark. | sunlight. | Ratio. +----------+-----------+---------------+---------------+---------- + | | ohms. | ohms. | + No. 22 |5 elements.| 39,000 | 340 |114 to 1 + " 23[6]|5 " | 14,000 | 170 | 82.3 " " + " 24[7]|5 " | 648,000 | 2,400 |270 " " + " 25 |5 " | 180,000 | 930 |196.5 " " + " 26 |5 " | 135,000 | 710 |190 " " + " 107 |5 " | 118,000 | 740 |159 " " + " 108 |5 " | 200,000 | 900 |222 " " + " 122 |5 " | 56,000 | 220 |254.5 " " + " 129[6]|5 " | 200,000 | 940 |212 " " + " 137 |5 " | 108,000 | 320 |337.5 " " +----------------------------------------------------------------- + +[Footnote 6: Cells No. 23 and No. 129 are now in possession of Prof. W. +Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, +and Prof. George F. Barker, of Philadelphia, has No. 26.] + +[Footnote 7: No. 24 was measured with a bridge multiplier of 6 to 1.] + +Cells which are sensitive to light improve by being used daily, and their +sensitiveness becomes less if they are laid aside and not used for a +considerable length of time, especially if allowed to become overheated. +They should be kept cool, and exposed to light frequently, whether they +are used or not. + +_Mode of measuring cells_.--So great is the sensitiveness of these cells +to external influences, that it is necessary to adopt some particular +system in measuring their resistance and to adhere strictly to that +system, as every change in the method of measurement produces a +difference in the result, and the different measurements would not be +comparable with each other. The reason for this will be explained +presently. + +The system I have adopted is the Wheatstone's bridge arrangement, with +equal sides, never using multipliers except for some experimental +purpose. In each multiplier wire I have 500 ohms resistance. When the +bridge is balanced, one-half of the current flows through the cell and +acts upon the selenium. Between the bridge and the cell is a reversing +switch, so that the current can be reversed through the cell without +changing its course through the bridge. A Bradley tangent galvanometer is +used, employing the coil of 160 ohms resistance. The Leclanche battery is +exclusively used in measurements for comparison. + +2. _The kind of battery employed_ has a marked effect upon the +sensitiveness to light, which is largely reduced or entirely destroyed +when the bichromate battery is used. The same cells again become +extremely sensitive with the Leclanche battery. We might expect that a +change in the current employed would cause a change in the _resistance_ +of a cell, but it is not clear how or why it should affect the +_sensitiveness of selenium to light_. + +"If one kind of battery current destroys its sensitiveness, may we not +suppose that another kind might increase its sensitiveness? Although the +Leclanche has operated well, some other may operate still better, and by +its special fitness for use on selenium cells may intensify their +actions, and so bring to light other properties yet unthought of. Is not +here a promising field for experiment, in testing the various forms of +battery already known, or even devising some new form especially adapted +to the needs and peculiarities of selenium cells?" + +One year ago I made the foregoing suggestion in a paper on _A New Form of +Selenium Cell_, presented before this Association at Minneapolis. I am +now at liberty to state that my photo-electric battery, presently to be +described, marks an advance in the direction indicated. The current from +this battery increases the sensitiveness of the cells to light, and also +to reversal of current. One cell whose highest ratio in light was about +83 to 1, with the Leclanche battery, when measured with my battery gave a +ratio of 120 to 1. It seems to make the resistance of the cell both +higher in dark and lower in sunlight than with the Leclanche battery. But +the field is yet open to others, for the discovery of a battery which may +be still better for use with selenium cells. + +3. _The two surfaces of the selenium act differently toward currents_ +sent into them from the contiguous conductors. One surface offers a +higher resistance to the current than the other. The former I utilize as +the anode surface, as I have found that the cell is more sensitive to +light when the current enters at that surface, which is ordinarily the +one covered by the gold or other transparent conductor. Some cells have +this property but feebly developed; but in one instance the resistance +offered to the current by the anode surface was 256 times as high as that +offered by the cathode surface to the same current. In the majority of +cases, however, the ratio does not exceed ten times. Table B gives some +recent results. + + TABLE B. + + SENSITIVENESS TO REVERSAL OF DIRECTION OF CURRENT. + +-----------------------+--------------+------------------+--------- + | | Resistance | + No. of cell. | Battery. | "gold | "gold | Ratio + | | anode."|cathode."| +-----------------------+--------------+--------+---------+--------- + | | ohms. | ohms. | +3/8 inch square. No. 4 | 5 elements. | 20,000 | 1,000 | 20 to 1 + " " " 3 | Se. cell. | 6,500 | 400 | 16.2 " + Full size, No. 13 | 1 element. | 9,000 | 800 | 11.2 " + " " " 14 | 5 " | 2,440 | 130 | 18 " + " " " 15 | 5 " | 4,640 | 210 | 22 " + " " " 27 | 5 " | 6,900 | 440 | 16 " + " " " 126 | 1 " | 5,000 | 330 | 15 " +-----------------------+--------------+--------+---------+--------- + +The direction of the current is always indicated by stating the position +of the gold electrode, by the terms "gold anode" and "gold cathode." The +above measurements were made in dark. + +4. _Sensitiveness to change of battery power_.--My cells are extremely +sensitive to any change in the strength or character of the current +flowing through them, which is shown by a corresponding change in the +resistance of the cell. I can, therefore, vary the resistance of one of +my cells in many ways, and the following may be specified-- + +(a) By changing the potential or electromotive force of the current +through the cell. + +(b) By changing the "quantity" of the battery or current. + +(c) By putting more or less resistance in the circuit. + +(d) By dividing the current, by one or more branch circuits or shunts +around the cell. + +(e) By varying the resistance in any or all of said circuits. + +A cell whose resistance becomes greater as the battery power becomes +greater, and _vice versa_, I call an "L B cell" signifying _Like the +Battery power_. A "U B cell" is one whose resistance becomes greater as +the battery power (or strength of current) becomes less, and _vice +versa_, being _Unlike the Battery power_, or current strength. + +These changes of resistance are not due to heating of the conductor or +the selenium, and the following instance will illustrate this. I have one +cell in which the selenium has about one-fourth inch square of surface +melted on a brass block one inch thick. This cell measured, with 25 +elements of Leclanche, 40,000 ohms. On changing the battery to 5 elements +the resistance fell instantly to 30 ohms, and there remained. On again +using the current from 25 elements, the resistance instantly returned to +40,000 ohms. Had these results been due in any degree to heating, the +resistance would have changed gradually as the heat became communicated +to the brass, whereas no such change occurred, the resistances being +absolutely steady. Moreover, even the fusion of the selenium would not +produce any such change. + +The "U B" property does not ordinarily change the resistance of the cell +to exceed ten times, i.e., the resistance with a weak current will not be +over ten times as high as with a strong one. But I have developed the "L +B" property to a far higher degree. Table C gives some recent results +obtained with L B cells, including one whose resistance, with 25 elements +Leclanche, was 11,381 times as high as with 8 elements, and which, after +standing steadily at 123 ohms (and then at 325 ohms with 1 element), on +receiving the current from 25 elements again returned to its previous +figure of 1,400,000 ohms. + + TABLE C. + + SENSITIVENESS TO CHANGE OF BATTERY POWER. +-----------------------+------------+------------+------------- + | Resistance | Resistance | + No. of cell. | with 25 | with 5 | Ratio of + | elements. | elements. | Change. +-----------------------+------------+------------+------------- + | ohms. | ohms. | +3/8 inch square, No. 1 | 40,000 | 30 | 1,333 to 1 +3/8 " " " 2 | 13,000 | 40 | 325 " +1/4 " " " 1 | 1,400,000 | 123[8] | 11,381 " +1/2 " " " 2 | 500,000 | 62 | 8,064 " +1/2 " " " 5 | 3,500 | 21 | 167 " + Full size, No. 81 | 68,000 | 121 | 561 " + " " " 82 | 9,000 | 64 | 140 " + " " " 83 | 17,300 | 74 | 233 " + " " " 119 | 35,600 | 19 | 1,894 " +-----------------------+------------+------------+------------- + +[Footnote 8: This measurement was obtained with 8 elements.] + +The results in the table were obtained by changing the strength of +current by throwing in more or less of the battery. Like results can be +obtained by varying the current through the cell by any of the other +methods before specified. The above measurements were in dark. + +5. _Dual state of selenium_.--My cells, when first made seem to have two +states or conditions. In one, their resistance is very low, in the other +it is high. When in the low state they are usually not very sensitive, in +any respect. I therefore raise the resistance, by sending an intermittent +or an alternating current though the cells, and in their new condition +they at once become extremely sensitive to light, currents, and other +influences. In some cases they drop to the low state again, and require +to be again brought up, until, after a number of such treatments, they +remain in the sensitive state. Occasionally a cell will persist in +remaining in the insensitive state. The before mentioned treatment raises +it up for a moment, but, before the bridge can be balanced and the +resistance measured, it again drops into the low or insensitive state. +Some cells have been thus stimulated into the high or sensitive state +repeatedly, and every means used to make them stay there, but without +avail; and they have had to be laid aside as intractable. + +In the earlier stages of my investigations, before the discovery of this +dual state and the method of changing a cell from the insensitive to the +sensitive condition, hundreds of cells were made, finished, and tested, +only to be then ruthlessly destroyed and melted over, under the +impression that they were worthless. Now, I consider nothing worthless, +but expect sooner or later to make every cell useful for one purpose or +another. + +The most singular part of this phenomenon is the wide difference in the +resistance of the cells in the two states. In the low state, it may be a +few ohms, or even a few hundredths of an ohm. In the high state, it is +the normal working resistance of the cell, usually between 5,000 and +200,000 ohms, but is often up among the millions. The spectacle of a +little selenium being stimulated, by a few interruptions of the current +through it, into changing its resistance from a fraction of an ohm up to +a million or several millions of ohms, and repeatedly and instantly +changing back and forth, up and down, through such a wide range, we might +almost say changing from zero to infinity, and the reverse, instantly, is +one which suggests some very far-reaching inquiries to the electrician +and the physicist. What is the nature of electrical conductivity or +resistance, and how is it so greatly and so suddenly changed? + +6. _Radio-electric current generators_.--My cells can be so treated that +will generate a current by simple exposure to light or heat. The light, +for instance, passes through the gold and acts upon its junction with +the selenium, developing an electromotive force which results in a +current proceeding from the metal back, through the external circuit, to +the gold in front, thus forming a photo-electric dry pile or battery. It +should preferably be protected from overheating, by an alum water cell or +other well known means. + +The current thus produced is radiant energy converted into electrical +energy directly and without chemical action, and flowing in the same +direction as the original radiant energy, which thus continues its +course, but through a new conducting medium suited to its present form. +This current is continuous, constant, and of considerable electromotive +force. A number of cells can be arranged in multiple arc or in series, +like any other battery. The current appears instantly when the light is +thrown upon the cell, and ceases instantly when the light is shut off. If +the light is varied properly, by any suitable means, a telephonic or +other corresponding current is produced, which can be utilized by any +suitable apparatus, thus requiring no battery but the selenium cell +itself. The strength of the current varies with the amount of light on +the cell, and with the extent of the surface which is lighted. + +I produce current not only by exposure to sunlight, but also to dim +diffused daylight, to moonlight, and even to lamplight. I use this +current for actual working purposes, among others, for measuring the +resistance of other selenium cells, with the usual Wheatstone's bridge +arrangement, and for telephonic and similar purposes. Its use for +photometric purposes and in current regulators will be mentioned further +on. It is undoubtedly available for all uses for which other battery +currents are employed, and I regard it as the most constant, convenient, +lasting, readily used, and easily managed pile or battery of which I have +any knowledge. On the commercial scale, it could be produced very +cheaply, and its use is attended by no expense, inasmuch as no liquids or +chemicals are used, the whole cell being of solid metal with a glass in +front, for protection against moisture and dust. It can be transported or +carried around as easily and safely as an electro-magnet, and as easily +connected in a circuit for use wherever required. The current, if not +wanted immediately, can either be "stored" where produced, in storage +batteries of improved construction devised by me, or transmitted over +suitable conductors to a distance, and there used, or stored as usual +till required. + +7. _Singing and speaking cells_.--When a current of electricity flowing +through one of my selenium cells is rapidly interrupted, a sound is given +out by the cell, and that sound is the tone having the same number of air +vibrations per second as the number of interruptions in the current. The +strength of the sound appears to be independent of the direction of the +current through the cell. It is produced on the face of the cell, no +sound being audible from the back of the cell. An alternating current +also produces a sound corresponding to the number of changes of +direction. Experiments also show that, if a telephonically undulating +current is passed through the cell, it will give out the speech or other +sound corresponding to the undulations of the current--and, furthermore, +that the cell will sing or speak in like manner, without the use of a +current, if a suitably varied light is thrown upon it while in closed +circuit. + +My experiments having been devoted especially to those branches of the +subject which promised to be more immediately practically valuable, I +have not pursued this inquiry very far, and offer it for your +consideration as being not only interesting, but possibly worthy of full +investigation. + +GENERAL OBSERVATIONS ON THE PROPERTIES OF CELLS. + +From the number of different properties possessed by my cells, it might +be anticipated that the different combinations of those properties would +result in cells having every variety of action. This is found to be the +case. As a general rule, the cells are noteworthy in one respect only. +Thus, if a cell is extremely sensitive to light, it may not be specially +remarkable in other respects. As a matter of fact, however, the cells +most sensitive to the light are also "U B cells." + +The property of sensitiveness to light is independent of the power to +generate current by exposure to light--the best current-generating cells +being only very moderately sensitive to light, and some of the most +sensitive cells generate scarcely any current at all. Current-generating +cells are, almost without exception, "U B cells;" and the best +current-generating cells are strongly polarized, showing a considerable +change of resistance by reversing the direction of a current through +them; and they are also strong "anode cells," i.e., the surface next to +the gold offers a higher resistance to a battery current than the other +surface of the selenium does. The power to generate a current is +temporarily weakened by sending a battery current through the cell while +exposed to light, in either direction. The current generated by exposure +to light is also weakened by warming the cell, unless the cell is +arranged for producing current by exposure to heat. + +The properties of sensitiveness to light and to change of battery power +are independent of each other, as I have cells which are sensitive to +change of current but absolutely insensitive to light--their resistance +remaining exactly the same whether the cells are in darkness or in +sunlight. I also have cells which are sensitive to light, but are +unaffected by change of battery power, or by reversing the direction of +the current through them. + +The sensitiveness to change of battery power is also independent of the +sensitiveness to reversal of direction of the current. Among the best "L +B cells," some are "anode cells" and others are "cathode cells," while +still others are absolutely insensitive to reversal of current or to the +action of light. + +_Constancy of the resistance_.--A noticeable point in my cells is the +remarkable constancy of the resistance in sunlight. Allowing for +differences in the temperature, the currents, and the light, at different +times, the resistance of a cell in sunlight will remain practically +constant during months of use and experiments, although during that time +the treatments received may have varied the resistance in dark hundreds +of thousands of ohms--sometimes carrying it up, and at others carrying it +down again, perhaps scores of times, until it is "matured," or reaches +the condition in which its resistance becomes constant. + +As has already been stated, the sensitiveness of a cell to light is +increased by proper usage. This increased sensitiveness is shown, not by +a lowered resistance in light, but by an increased resistance in dark. +This change in the cells goes on, more or less rapidly, according as it +is retarded or favored by the treatment it receives, until a maximum is +reached, after which the resistance remains practically constant in both +light and dark, and the cell is then "matured," or finished. The +resistance in dark may now be 50 or even 100 times as high as when the +cell was first made, yet, whenever exposed to sunlight it promptly shows +the same resistance that it did in the beginning. The various treatments, +and even accidents, through which it has passed in the mean time, seem +not to have stirred its molecular arrangement under the action of light, +but to have expended their forces in modifying the positions which the +molecules must normally assume in darkness. + +_Practical applications_.--There are many peculiarities of action +occasionally found, and the causes of such actions are not always +discernible. In practice, I have been accustomed to find the +peculiarities and weaknesses of each cell by trial, developing its +strongest properties and avoiding its weaknesses, until, when the cell is +finished, it has a definite and known character, and is fitted for +certain uses and a certain line of treatment, which should not be +departed from, as it will be at the risk of temporarily disabling it. In +consequence of the time and labor expended in making cells, in the small +way, testing, repairing damages done during experiments, etc., the cost +of the cells now is unavoidably rather high. But if made in a commercial +way, all this would be reduced to a system, and the cost would be small. +I may say here that I do not make cells for sale. + +The applications or uses for these cells are almost innumerable, +embracing every branch of electrical science, especially telegraphy, +telephony, and electric lighting, but I refrain from naming them. I may +be permitted, however, to lay before you two applications, because they +are of such general scientific interest. The first is my + +_Photometer_.--The light to be measured is caused to shine upon a +photo-electric current-generating cell, and the current thus produced +flows through a galvano-metric coil in circuit, whose index indicates +upon its scale the intensity of the light. The scale may be calibrated by +means of standard candles, and the deflections of the index will then +give absolute readings showing the candle power of the light being +tested. Or, the current produced by that light and that produced by the +standard candle may be compared, according to any of the known ways of +arranging and comparing different lights--the cell being lastly exposed +alternately to the two lights, to see if the index gives exactly the same +deflection with each light. + +This arrangement leaves untouched the old difficulty in photometry, that +arising from the different _colors_ of different lights. I propose to +obviate that difficulty in the following manner. As is well known, gold +transmits the green rays, silver the blue rays, and so on; therefore, a +cell faced with gold will be acted upon by the green rays, one faced with +silver by the blue rays, etc. Now, if we construct three cells (or any +other number), so faced that the three, collectively, will be acted upon +by all the colors, and arrange them around the light to be tested, at +equal distances therefrom, each cell will produce a current corresponding +to the colored rays suited to it, and all together will produce a current +corresponding to all the rays emitted by the light, no matter what the +proportions of the different colors may be. The three currents may act +upon the same index, but each should have its own coil, not only for the +sake of being able to join or to isolate their influences upon the index, +but also to avoid the resistances of the other cells. If a solid +transparent conductor of electricity could be found which could be thick +enough for practical use and yet would transmit all the rays perfectly, +i.e., transmit white light unchanged, that would be still better. I have +not yet found a satisfactory conductor of that kind, but I think the plan +stated will answer the same purpose. This portion of my system I have not +practically tested, but it appears to me to give good promise of removing +the color stumbling-block, which has so long defied all efforts to remove +it, and I therefore offer it for your consideration. + +_Photo-electric regulator_.--My regulator consists of a +current-generating cell arranged in front of a light, say an electric +lamp, whose light represents the varying strength of the current which +supports it. The current produced in the cell by this light flows through +an electro-magnetic apparatus by means of which mechanical movement is +produced, and this motion is utilized for changing resistances, actuating +a valve, rotating brushes, moving switches, levers, or other devices. +This has been constructed on a small scale, and operates well, and I +think it is destined to be largely used, as a most sensitive, simple, and +perfect regulator for currents, lights, dynamos, motors, etc., etc., +whether large or small. + +In conclusion, I would say that the investigation of the physical +properties of selenium still offers a rare opportunity for making very +important discoveries. But candor compels me to add that whoever +undertakes the work will find it neither an easy nor a short one. My own +experience would enable me to describe to you scores of curious +experiments and still more curious and suggestive results, but lack of +time prevents my giving more than this very incomplete outline of my +discoveries. + + * * * * * + + + + +ELECTRICITY APPLIED TO THE MANUFACTURE OF VARNISH. + + +Messrs. Muethel & Luetche, of Berlin, recommend the following process for +the manufacture of varnish: The oils are treated by gases or gaseous +mixtures that have previously been submitted to the action of electric +discharges. The strongly oxidized oxygenated compounds that are formed +under such circumstances give rise, at a proper elevation of temperature, +to compounds less rich in oxygen, and the oxygen that is set free acts +upon the fatty acid that it is proposed to treat. A mixture of equal +parts of chlorine and steam may be very advantageously employed, as well +as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric +acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide +of nitrogen and air, or oxygen, and so on. + +The apparatus is shown in section in the accompanying engraving; a is a +steam-pipe running from the boiler to the motor. From this pipe branch +conduits, b, that enter the vessels, B, in which the treatment is +effected, and that run spirally through the oil. At the lower part of the +vessel, B, there is tube wound into a flat spiral, and containing a large +number of exceedingly small apertures. + +The oxidizing apparatus is shown at p. The gaseous mixture enters through +the tube, n, traverses the apparatus, p, and enters the vessel, B, +through the tubes, g and D. Fig. 2 gives the details of the oxidizing +apparatus, which consists of two concentric glass tubes, A and F, +soldered at x. A is closed beneath and held in a cylinder, C; F contains +a small aperture through which passes a tube, E. The gaseous mixture +enters through the latter, traverses the annular space between the tubes, +A and F, and then makes its exit through H, whence it goes to a similar +apparatus placed alongside of the other. The shaded parts of the +engraving represent bodies that are good conductors of electricity and +that communicate with the two poles of any electrice source whatever. + +[Illustration: FIGS. 1 AND 2.] + +The operation is as follows: After opening the tube, e, linseed oil is +introduced into the vessel, B, until the latter is half full, and, after +this, e is closed and the worm, S, is allowed to raise the temperature to +between 60 deg. and 80 deg.. Then the cock of the tube, d, which communicates +with an air pump, is opened, and the pressure is diminished to about 730 +mm. of mercury. At this moment the oxidizing apparatus are put in +communication with an induction bobbin that is interposed in the circuit +of a dynamo, while through the tube, n, there is made to enter a mixture +of equal parts (in volume) of sulphurous acid, oxygen, and air. At the +same time, the cock of the tube, g, is opened, while the stirrer, T, is +set in motion. In this way we obtain, in a much shorter time than by +ordinary processes, a very liquid, transparent varnish, which, when +exposed to the air, quickly hardens. It is possible, with the same +process, to employ a mixture (in volumes) of two parts of protoxide of +nitrogen with one and a half parts of atmospheric air, or even protoxide +of nitrogen alone. + +When it is judged that the operation is finished, the tube, g, is opened, +the stirrer is stopped, and the tube, c, is opened after d has been +closed. The steam then forces the varnish to pass through the tube, f, +and traverse the washing apparatus, which is filled half full of water, +that is slightly ammoniacal, and is heated by a circulation of steam, S. +Finally, the product, washed and free from every trace of acid is +collected upon making its exit from the tube, h.--_La Lumiere +Electrique._ + + * * * * * + + + + +NAGLO BROTHERS' TELEPHONE SYSTEM. + + +We borrow from the _Elektrotechnische Zeitung_ the following details in +regard to the telephonic installations made by the Brothers Naglo at +Berlin. Fig. 1 gives the general arrangement of a station, where J is an +inductor set in motion through a winch, K, and a pair of friction +rollers; W, a polarized call; U, an ordinary two-direction commutator; B, +a lightning protector; and L and T, the two terminals of the apparatus, +one of them connecting with the line and the other with the earth. The +interesting point of this system is the automatic communication which +occurs when the inductor, J, is moved. At the same moment that the winch, +K, is being moved, the disk, P, is carried from right to left and brought +into contact with the spring, f_{2}. As soon as the winch is left to +itself a counter-spring forces the disk, P, to return to a contact with +the spring, f_{1}. Figs. 2 and 3 show the details of such communication. +The winch, K, is keyed to one of the extremities of a sleeve that carries +the disk, P, at its other extremity. This sleeve is fixed upon the axle +of the first friction roller, that is to say, upon the axle that controls +the motion of the inductor, and is provided at the center with two +helicoidal grooves, e, at right angles with one another. In these grooves +slides a tappet, n, connected with the axle. + +[Illustration: FIG. 1.] + +Under the influence of the counter-spring at the left of the disk, P, the +latter constantly tends to occupy the position shown in Fig. 2, which is +that of rest. As soon as the winch, K, is revolved, whatever be the +direction of the motion, the axle can only be carried along when the +tappet, n, has come to occupy the position shown in Fig. 3, that is to +say, when the disk has moved from right to left a distance corresponding +to the fraction of the helix formed in the sleeve. + +This stated, it is easy to understand the travel of the currents. Fig. 1 +shows the station at rest. The current that arrives through L passes +through the lightning protector, the body of the commutator, U, the +terminal, v, and the call, W, bifurcates at P, and is closed by the +earth. The inductor is in circuit, but, as it is in derivation, upon a +very feeble resistance, v, nearly the whole of the current passes through +the latter. When it is the station that is calling, the call, W, is put +in derivation upon the circuit, f_{2} p, h, so that the portion of the +circuit that passes through q W v is exceedingly feeble, and incapable of +operating the bell of the post that is calling. + +[Illustration: FIGS. 2 AND 3.] + +Finally, when the telephone is unhooked, the inductor, J, and the bell, +W, are thrown out of circuit, and the telephone is interposed between d +and i, that is, between L and T.--_La Lumiere Electrique_. + + * * * * * + + + + +THE GERARD ELECTRIC LAMP. + + +In the Gerard incandescent lamp the carbons have the form of a V. They +are obtained by agglomerating very finely powdered carbon, and passing it +through a draw plate. At their extremity they are cemented together with +a small quantity of carbon paste, and their connection with the platinum +conducting wires is effected by means of a cylinder of the same paste +surmounted by a cone. These couplings secure a good contact, and, by +their dimensions, prevent the attachments from becoming hot and +consequently injuring the carbon at this point. The cone forms a +connection of decreasing section, and prevents the carbon from getting +broken during carriage. + +This process of manufacture permits of obtaining lamps of all +intensities, from 3 candles up. The following, according to Mr. Gerard, +are the consumptions of energy in each size of lamp: + + Candles. Volts. Amperes. + No. 0. 10 16 1.5 + " 1. 25 25 2 + " 2. 50 30 2.5 + +[Illustration: GERARD'S INCANDESCENT LAMP.] + +It will be seen that these lamps require a relatively intense current +with much less fall of potential than the Swan, for example--this being +due to the diameter of the filament. But, what is an inconvenience as +regards mounting, if we wish to supply them by ordinary machines (for +they must be mounted in series of 3 on each derived circuit if the +machine gives, as most frequently the case, 100 volts), is an advantage +as regards the quality and steadiness of the light and the duration of +the lamps. + +The part in which the energy is expended is homogeneous, as might be +supposed from the mode of manufacture, and as may be ascertained from a +microscopical examination, and it is exempt from those variations in +composition that are found in carbons of a vegetable nature, like the +Edison. Besides, being of relatively large diameter, the lamp is capable +of supporting a very great increase of temperature. + +The process employed for fixing the lamps is as simple as can be. Each +platinum wire is soldered to a piece of copper that surrounds the base of +the lamp and that is fixed to the glass with a special cement. These two +armatures intertwine, but at a sufficient distance apart to prevent +contact. They carry a longitudinal projection and an inflation that fit +by hard friction into two copper springs connected electrically with the +circuit. It is only necessary to lift the lamp in order to remove it from +the support; and the contrary operation is just as easy.--_Le Genie +Civil_. + + * * * * * + + + + +A NEW REFLECTING GALVANOMETER. + + +Fig. 1 shows an elevation of the instrument and a horizontal section of +the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes +of each pair are parallel and in the same vertical plane. Each pair is +supported by a vertical brass plate, and the two plates make an angle of +about 106 deg. with each other, so that the planes containing the axes of the +bobbins make an angle of about 74 deg.. Two horseshoe magnets, m m, made of +1/25 inch steel wire, are connected by a very light piece of aluminum and +placed at such a distance from each other that, on being suspended, the +two branches of each of the magnets shall freely enter the respective +bores of the two bobbins fixed upon the same plate, and, when the whole +system is in equilibrium and the bobbins free from current, the two +branches of each of the magnets shall nearly coincide with the axes of +such bores. The magnets are not plane, but are curved so as to form +portions of a vertical cylinder whose axis coincides with the direction +of the suspension wire, and to which the axes of the bobbins are tangent +at their center, approximately to the points where the poles of the +magnets are situated. + +[Illustration: FIG. 1. GRAY'S GALVANOMETER.] + +The needles have been given this form so that their extremities shall not +touch the sides of the bore during considerable deflections. + +In the instrument which the inventors, Messrs. T. & A. Gray, used in +their experiments upon the resistance of glass, the needles were arranged +so that their poles of contrary name were opposite. + +[Illustration: FIG. 2.] + +The system of needles is suspended from the extremity of a screw, p, +which passes into a nut, n, movable between two stationary pieces. On +revolving the nut, we cause the screw to rise or lower, along with the +entire suspended part, without twisting the thread. + +The four bobbins are grouped for tension, and have a total resistance of +30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming +62,939 revolutions, nearly equally divided between the four bobbins. When +a current is passing through the bobbins, the poles of one of the +horseshoe magnets are attracted toward the interior of the corresponding +bobbins, while those of the other are repelled toward the exterior by the +two other bobbins. We thus have a couple which tends to cause the system +to revolve around the suspension axis. A mirror, which is fixed upon a +vertical piece of aluminum, a, gives, in the usual manner, a reflected +image upon a scale, thus allowing the deflections to be read. A +compensating magnet, M, is supported by a vertical column fixed to the +case, above the needles. This magnet may be placed in the different +azimuths by means of a tangential screw, t. The extremities of the bobbin +wires are connected with three terminals, T, T', T squared, and the +instrument may, by a proper arrangement, became differential. These +terminals, as well as the communicating wires, are insulated with +ebonite. + +Thus arranged, the instrument is capable of making a deflection of one +division of 1/50 inch upon a scale placed at a distance of a little more +than a yard, with the current produced by one daniell of 10 ohms. This is +a degree of sensitiveness that cannot be obtained with any of the astatic +instruments known up to the present. By regulating the needles properly, +a greater degree of sensitiveness may be attained, but then the duration +of the needles' oscillation becomes too great. The sensitiveness of the +instrument is sufficiently great to allow it to be used in many cases, +even with a moderate duration of oscillation. + +In their experiments upon the resistance of glass, the inventors employed +an instrument that was not arranged for giving great sensitiveness, and +one with which resistances of from 10^{4} to 10^{5} megohms could be +measured by the use of a pile of 120 daniells. + +The instrument can be given another form. The four bobbins may be +arranged symmetrically in the same plane, and the two horseshoe magnets +be supported by an S-shaped aluminum bar. The latter traverses the plate +that supports the bobbins, in such a way that one of the magnets enters +one of the bobbins that correspond to it on one side of the plate, and +the other on the other side, as shown in Fig. 2. The bobbins are so +connected that, when they are traversed by a current, both magnets are at +the same time attracted toward the interior or repelled toward the +exterior of the bobbins. Such a form of the instrument has the advantage +of being more easily constructed, while the regulation of the magnets +with respect to the bore of the bobbins is easier. + +The chief advantage of the instrument results from the fact that, owing +to the arrangement of the magnets and bobbins, a large portion of the +wires of the latter is situated very near the poles of the magnets, and +in a position very favorable for electro-magnetic action. The instrument +presents no difficulties as regards construction, and costs no more than +an ordinary one. + +We might even arrange a single horseshoe magnet, or an S-shaped one, +horizontally, and employ but a single pair of bobbins, and thus have a +non-astatic apparatus based upon the same principle. But in astatic +instruments it is better to place the magnets in such a way that the two +branches shall be in the same vertical plane. + +Were the line that joins the two poles vertical, the system would be +perfectly astatic in a uniform field, since each magnet in particular +would then be perfectly astatic. A pair of horseshoe magnets may thus be +regulated in such a way as to form a perfectly astatic system in a +uniform field and to preserve an almost invariable zero, this being +something that it is very difficult to obtain with the ordinary +arrangement of needles, especially when a compensating magnet is used; +for, in such a case, one of the needles becomes more or less magnetized, +while the other becomes demagnetized, according to the position of the +compensating magnet.--_La Lumiere Electrique_. + + * * * * * + + + + +HISTOLOGICAL METHODS. + + +A cat, dog, rabbit, or Guinea pig will furnish parts from which sections +can be cut for the study of histology. Whichever animal is selected +should be young and well developed. Put it under influence of chloroform, +and open into the cavity of the chest; make an incision into the right +ventricle, and allow the animal to bleed to death; cut the trachea and +inject the lungs with a solution of one and a half drachms of chromic +acid in one quart of water, care being taken not to overdistend the lung. +Tie the severed end to prevent the escape of the fluid, and carefully +remove the lung. It is a difficult thing to do this without rupturing it, +but with care and patience it can be done. Place the lungs in a solution +of the same strength as used for injecting; after fifteen or twenty hours +change it to a fresh solution, and allow it to remain for about a month, +and then change it to rectified spirits, in which it may remain until +required. + +Cut the tongue into several transverse and longitudinal pieces, also the +small intestines, and put them into a solution of fifteen and one-half +grains chromic acid, thirty grammes bichromate of potash, and three pints +of water; change the solution the next day, and let them remain two weeks +and then place in spirits. Cut longitudinal and transverse portions of +the stomach and large intestines, wash in a weak solution of salt and +water, and put them in the same solution as used for the lungs, and treat +similarly. + +Cut the kidneys longitudinally and transversely, and put them in a +solution of six and one-half drachms bichromate of potash, two and +one-half drachms sodium sulphate, one quart of water; change the solution +the next day, and at the end of four weeks transfer to alcohol. Wash the +inner surface of the bladder with salt and water, and after cutting it +longitudinally and transversely, put the sections in a solution of three +drachms bichromate of potash in a quart of water. Cut the liver into +small parts, and place in the same solution as used for the kidneys; +change the solution after a day, and let them remain four or five weeks, +then change to spirits. The spleen and portions of the thin abdominal +muscles may be placed in a solution of three drachms chromic acid to one +quart of water, and transferred to alcohol after three or four weeks. +Carefully remove an eye and divide it behind the crystalline lens, put +the posterior portion in a solution made by dissolving fifteen grs. +chromic acid in five drachms water, and slowly adding five and one-half +ounces alcohol; change to spirits in two weeks. The lens should be put in +the same solution, but should remain a few days longer. Open the head, +remove the brain, and place transverse and longitudinal sections of it +in spirits for eighteen hours, then transfer to a solution of one drachm +chromic acid in a quart of water, and let it remain until hard enough to +cut. Place the uterus in a solution of one and one-half drachms chromic +acid in one quart of water, change to a new solution the next day, and at +the end of a month transfer to alcohol. + +The bones from one of the legs should be carefully cleaned of its +muscles, cut into several pieces, and placed in a solution of fifteen and +one-half grains chromic acid, one-half drachm nitric acid, and six ounces +water. Change the fluid frequently until the bones are sufficiently +softened, and then change to alcohol. + +_Section cutting_ machines for cutting sections can be procured of the +dealers, but a very simple and effective one can be easily made if one +does not wish to go to the expense of buying an instrument. + +A strip of wood twelve or fourteen inches long and about two inches wide +has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This +is covered with a brass plate, c, pierced with a hole one-half of an inch +in diameter. This hole extends through the wood, and is fitted with a +piston. Two long narrow inclined planes of nearly equal inclination, b, +b, grooved to slide on each other, are placed under the bridge; the lower +is to be fastened to the board; the end of the piston rests on the upper +one. The object from which we desire to cut a section is placed in the +hole, in the piston. If the upper plane be pushed in, the piston will be +forced upward, and with it the object. As the inclination of the plane is +very gradual, the vertical motion will be very slight as compared with +the horizontal. + +When the object is raised a little above the brass plate, a keen edged +razor, thoroughly wet, is pushed over the hole, cutting the object. This +gives the section a smooth surface, and even with the plate; now push the +plane forward one-eighth to one-quarter of an inch, and cut again; this +will give a thin section of the object. The thickness of the section +depends, of course, on the distance the wedge is pushed. + +With a little practice, much better sections can be cut by the hand than +by any machine; this does not apply of course to large sections. A razor +of good steel, with a blade thin and hard, are the most essential points +in an instrument for hand cutting. For ordinary purposes it is not +necessary to have the blade ground flat on one side, although many prefer +it. The knife should always be thoroughly wet, in order that the cut +tissue may float over its surface. Water, alcohol or salt and water may +be used for this purpose. + +[Illustration: FIG. 1.] + +_To out a section by hand_, hold the object between the thumb and first +two fingers of the left hand, supporting the back of the knife by the +forefinger. The knife is to be held firmly in the right hand, and in +cutting should never be pushed, but drawn from heel to point obliquely +through the tissue. The section should be removed from the knife by a +camel's hair brush. + +When the object is too small to hold, it is usually _embedded_ in some +convenient substance. A carrot is sometimes very useful for this purpose. +A hole rather smaller than the object is cut out of the middle. Put +whatever is to be cut into this, and cut a thin section of the whole. The +carrot does not cling to either the knife or the section, and the knife +is wetted at every slice by it. + +Paraffin is the agent usually employed for embedding purposes. Melt it, +and add a little lard to soften it; the addition of a little clove oil +renders it less adhesive. + +Melt the paraffin at as low a temperature as possible, and pour it into a +paper cone. Dip the object into this and remove immediately; as soon as +the layer of paraffin surrounding it becomes hardened, replace it in the +paraffin; this prevents overheating the tissues. + +Where the tissues are too soft to be cut, they may be soaked in a +solution of gum arabic and dried; in this condition they can be readily +cut, after which the gum can be dissolved off. This is an extremely +useful method for cutting the lung or other organs where an interstitial +support is needed. For a very thin object, a cork fitting any kind of a +tube is to be split, and the object placed between the two parts; the +cork is then thrust into the tube, and a sufficient degree of firmness +will be obtained to allow cutting. The sections should always be +manipulated with camel's hair brushes. + +Much practice will be required before dexterity is attained. + +_Methods of preserving the tissues_.--All water must be removed from the +tissue, either by drying or by immersing it in rectified spirits, and +then in absolute alcohol, and the alcohol driven off by floating it upon +oil of clove or turpentine. The substances used to preserve the tissues +are Canada balsam, Dammar balsam, glycerine, Farrant's solution, +potassium acetate, spirits, naphtha, and creosote. + +The section is to be floated on to the slide or placed in position with a +camel's hair brush. It should be spread out, and then examined under the +microscope for the purpose of improving its position if necessary, or of +removing any foreign particles. A drop of the preserving medium is then +placed upon it, and another placed on the cover and allowed to spread +out. The cover is then taken by a pair of pincers and inverted over the +object, and one edge brought to touch the slide at one part of its +margin. The cover is then gently lowered, and the whole space beneath the +cover filled and the tissue completely saturated. If air bubbles show +themselves, raise the cover at one corner and deposit a further quantity +of the medium. + +The slide should be set aside for a few days. First, the excess of the +medium must be removed; if it is glycerine, much of it can be removed by +a piece of blotting paper, but the cover must not be touched, for it is +easily displaced; that near the cover can be replaced by a camel's hair +brush. A narrow ring of glycerine jelly should be placed around the edge +of the cover, to fix it before the cement is applied. When this has set, +a narrow strip of cement is to be put on, just slightly overlapping the +edge of the cover and outside the margin of the jelly. Until it has been +perfectly secured, a slide carrying glycerine must never be placed in an +inclined position, as its cover will slide off. + +_Preservative media_.--Canada balsam may be prepared as follows: Place +some pure Canada balsam in a saucer, and cover with paper to exclude +dust; dry it in an oven at a temperature of 150 deg.; when it cools, it will +become hard and crystalline. Dissolve this in benzole, and use in the +same way as glycerine. + +Dammar is now used as a substitute for Canada balsam. By its use the +tissues are rendered more transparent. To prepare it, dissolve one-half +ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of +benzole, and filter. This may be used to mount unsoftened bone and tooth, +hair, brain, and spinal column, and most tissues that have been hardened +in alcohol or chromic acid, which require to have their transparency +increased. + +Glycerine is not adapted for white fibrous tissue or blood vessels, +unless they have been hardened in chromic acid, as it causes the white +fibers to swell up and lose their normal features. Sections of liver, +lung, skin, and alimentary canal show better in glycerine unless they +have been stained. + +Farrant's solution may be substituted for glycerine in many instances, +because of its feebler tendency to render the tissues transparent. It +consists of equal parts of gum arabic, glycerine, and a saturated +solution of arsenious acid. In mounting preparations with this medium, +the covered object should be allowed to lie a day before the varnish is +applied, so that the cover may be fixed, and thereby prevented from being +displaced. Rectified spirits may be used for mounting softened bone and +tooth, and naphtha and creosote are useful for preserving urinary casts. + +When the section is mounted in Canada or Dammar balsam, no cement is +required, but for all other preservative media the margin of the cover +must be covered with cement. To do this, dry the edges of the cover +thoroughly with bibulous paper, and paint a layer of gold size, allowing +it to overlap the cover an eighth or sixteenth of an inch, then cover +this with white zinc cement. + +_Preparation for mounting the different tissues_.--To obtain a section of +bone or tooth requires a grinding down of the tissue until it is so thin +as to be transparent. A section should first be cut as thin as possible +by a fine saw. It should be attached by the flattest side to a piece of +glass, and then ground down by a grindstone or by very fine emery, on a +perfectly flat piece of lead. When sufficiently thin and transparent, +mount in rectified spirits or Dammar. Sections of the tongue may be made +by embedding in paraffin, and mounted in Farrant's solution or glycerine. + +Sections of the stomach may also be made by embedding in paraffin, but +better ones can be made by freezing. Farrant's solution makes a good +mounting. + +The intestines also give a better section from freezing than by +embedding, as the paraffin injures the villi; mount in the same medium as +the stomach. + +The liver may be embedded in paraffin, and the section mounted in +Farrant's solution or glycerine. The kidney may be treated in the same +way. The cornea of the eye can be readily cut by embedding in paraffin, +and the section may be mounted in Farrant's solution. The crystalline +lens and retina may be treated similarly. + +The brain and spinal cord should be embedded in paraffin or a carrot, and +the section mounted in Dammar. Sections of the uterus and ovaries are +best mounted in glycerine or Dammar. Sections of lung maybe made by +embedding in gum or by freezing, and mounted in Farrant's solution. + +Every slide should be of uniform size, and labeled. The usual size is 3x1 +inches, and should be of a good quality of glass, free from scratches or +air holes. They may be labeled either by writing with a diamond, or a +small piece of paper affixed to one end, on which is written what is +required. + + * * * * * + + + + +LIFE HISTORY OF A NEW SEPTIC ORGANISM. + + +At a recent meeting in London, of the Royal Miscroscopical Society, Dr. +Dallinger gave his annual address to what was probably the largest +gathering of Fellows ever assembled on a similar occasion. After briefly +referring to the increased interest lately manifested in the study of +minute organisms, and recalling the characteristics of the doctrines of +abiogenesis and biogenesis, he passed rapidly in review the results of +the observations of Tyndall, Huxley, and Pasteur as bearing upon these +questions, and called attention to the observations of Buchner as to the +transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice +versa_, and referred with approval to Dr. Klein's criticisms thereon. +Having spoken of the desirability of careful and continuous study of this +class of organisms, and the importance of endeavoring to establish the +relation of the pathogenic form to the whole group, he said he should be +better able to deal with the subject by recording a few ascertained facts +rather than by making a more extended review, and he therefore devoted +the main part of his address to a description of "the life history of a +septic organism hitherto unknown to science." In his observations of this +form--extending over four years--he had the advantage of the highest +quality of homogeneous lenses obtainable, ranging from one-tenth to +one-fiftieth of an inch, his chief reliance being placed upon a very +perfect one thirty-fifth of an inch; and from the continuous nature of +the observations as well as the circumstances under which they were +carried on, dry lenses had for the most part to be employed. Having in +his possession a maceration of cod-fish in a fluid obtained from boiled +rabbits, he found at the bottom of it, when in an almost exhausted +condition, a precipitate forming a slightly viscid mass, to which his +attention was particularly directed. It was seen to contain a vast number +of _Bacterium termo_, but on examination with a one-tenth inch objective +showed that it also contained a comparatively small number of intensely +active organisms--one being discovered in about eight or ten drops of the +sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an +inch in breadth. The fluid had originally been kept at a temperature of +90 deg. to 95 deg. F., and it was noticed that, when placed upon a cold stage +under the microscope, the movements of the organisms became, gradually +slower, until at last they entirely ceased; the necessity, therefore, +arose for the use of a warm stage, and the very ingenious contrivance by +which a continuous and even temperature was maintained within the +one-tenth of a degree was exhibited. The greatest difficulty in the +matter was, however, experienced in obtaining specimens for observation, +in order to be able to trace them from their earliest to their latest +stage. The President then explained, by means of an admirable series of +illustrations projected upon a screen by the oxyhydrogen lantern, the +life history of the organism to which he had referred, exhibiting it +first as a translucent, elliptic, spindle-shaped body, with six long and +delicate flagella, the various positions in which the five specimens were +drawn giving a very good idea of its peculiar porpoiselike movements. + +The various positions which it assumed in making an attack upon a portion +of decomposed matter were also shown, the movements quite fascinating the +observer by their rhythmical character. The supposed action of the +flagella in the production of the movements observed was explained, +distinct evidence being afforded of a remarkable spiral motion, at least +of those behind. The process of fission was illustrated in all its +observed stages from the first appearance of a construction to that of +final and complete separation, the whole being performed within the space +of eight or nine minutes. A description of the process of fusion from the +simple contact of two organisms to their entire absorption into each +other followed, as well as their transformation into a granular mass, +which gradually decreased in size in consequence of the dropping of a +train of granules in it wake as it moved across the field. The +development of these granules was traced from their minute semi-opaque +and spherical form to that of the perfect flagellate organism first +shown, the entire process being completed in about an hour. Experiments +as to their thermal death-point showed that, while the adults could not +be killed by a temperature less than 146 deg. F., the highest point endured +by the germs was 190 deg. F. Illustrations of a variety of other modes of +fission discovered in previous researches on similar forms were given, +showing the mode of multiple division and a similar process in the case +of an organism contained in an investing envelope. The President +concluded his address, which was listened to throughout with the greatest +attention, by remarking that, though the processes could be seen and +their progress traced, the _modus operandi_ was not traceable. Yet the +observer could not fail to be impressed with the perfect concurrent +adaptation of these organisms to the circumstances of their being; they +were subject to no caprices, their life-cycles were as perfect as those +of a crustacean or a bird, and while the action of the various processes +was certain, their rapidity of increase and the shortness of their life +history were such that they afforded a splendid opportunity of testing +the correctness of the Darwinian law. + + * * * * * + + + + +WINTER AND THE INSECTS. + + +For a number of years previous to 1878 we had in Pembroke but little or +no severe cold, owing to the prevalence of southeast, south, west, and +especially southwest winds. In many places, fuchsias that were left in +the ground for the entire year had not been frozen to the root within the +memory of man. Some of these plants had grown to be trees five or six +yards in height, and with a trunk the size of one's leg. Now, during the +same series of years, many insects that are common throughout the rest of +Great Britain did not cease to be rare with us, or rather were confined +to certain circumscribed limits. Thus, the Noctuellae, with the exception +of a few species abundant everywhere, were almost wanting, and I know of +no other country where the dearth of common species of nocturnal +butterflies was so great. But during the winter of 1878 there supervened +a radical change. Persistent winds from the northwest, driving back the +currents of warm air from the south, brought on an intense cold that +froze everything; or, when some variation occurred in them, clouds formed +and dissolved into a rain that immediately froze, so that the large roads +remained for weeks covered with a layer of rime from two to four inches +thick. + +[Illustration: GREEN WOODPECKER SEARCHING FOR INSECTS.] + +The winters of 1879 and 1880 were equally cold; we may even say that the +latter was the severest that had been experienced in fifty years. This +year the sea-sand, along with the ice and snow, formed a thick crust all +along the tide-line--this being something rarely seen along our coast. +The first of these three winters (1878-1879) killed all the arborescent +veronicas and a few sumacs. As for the fuchsias and myrtles, they were +frozen down to the level of the soil. + +I now come to the effects of this severe cold upon the insects. + +The Lepidoptera, which before were rare, became more and more common in +1879, 1880, and 1881, and so much so that during the last named year they +abounded; and species that had formerly been detected only at certain +favored points spread over the entire coast and into the interior of the +country. The geometers appeared in numbers that were unheard of. But this +change was especially striking as regards the Noctuellae, in view of the +previous rarity of the individuals belonging to this family. + +We have here an example of the direct relation of cause to effect, +although I am not in a position to assert that the effect is always +produced in the same way. To me there is no question as to the fact that +the constitution of those insects which nature has accorded the faculty +of liberating is strengthened, and that their chances of life are +increased, if the cold of winter is intense enough to plunge them into an +absolute rest, and is not unseasonably affected by warm, spring-like +days. It is certain that such cold is capable of contributing largely to +the multiplication of the individuals of such species as hibernate in the +egg state, and it also has a beneficent influence upon those species +which, like the small social larvae, pass this season upon the earth +enveloped in a silken envelope, or, like the larvae of the Noctuellae, +between dead leaves or upon the ground itself. + +On another hand, it cannot be doubted that mild winters greatly +contribute to the bringing about of a destruction of larvae and chrysalids +in two ways: First, they favor the development of mould, which, as well +known, attacks the larvae of insects when these have been enfeebled by an +excess of rain or dampness; and second, they permit beasts of prey to +continue to exercise their activity. Now, these latter are numerous. +Moles, instead of burying themselves deeply, then continue to excavate +near the surface, and shrew mice are constantly in search of food. These +small mammals, which abound in this district, destroy a large number of +chrysalids of Lepidoptera. + +It is the same with birds. As soon as severe cold begins to prevail in +the north and east, they come in troops to the open fields and the +sheltered slope of the hills of our district. But it is scarcely worth +while to stop to tell of the skill and perseverance of these destroyer of +larvae. We may mention, the woodpecker, however, as a skillful searcher +for insects that lie hidden in places where the sun has melted the snow. +The carnivorous Coleoptera and the Forficulae are likewise generally in +motion during mild winters. Doubtless these last-named do not make very +large inroads in the ranks of larvae and chrysalids every day; yet, having +no other food, they destroy a goodly number of them. But I believe that +the devastations made in the army of insects by all these enemies united +do not equal those made by certain crustaceans--the wood lice. + +During mild winters these pests multiply, eat, and prosper out of bounds, +and to such a point that, in a climate like ours, they become a true +scourge that prevails everywhere, out of doors and within. Once in a +place, they begin to look for larvae and chrysalids, which they devour. +The severe cold seems to have destroyed a certain number of them, since +they are now not so numerous by far; and it has at least certainly put a +stop to their devastations at an epoch when the larvae are more +particularly exposed to the attacks of their enemies. It is to this +cause, as well as to the preceding, that I am led to attribute the +extraordinary multiplication of so many species during the three last +summers, which were separated by severe winters. Last winter was mild, +and there is therefore no reason to expect that there will be another +multiplication; but I hope that the harm done by such a season will be +slight. It is the progressive multiplication of the destroyers, joined to +the correlative disappearance of the victims caused by a series of +temperate seasons, that is to be feared. + +In support of the proposition that I maintain, I may mention still +another fact. While this district (Pembroke, Wales) is relatively poor in +species whose larvae feed and hibernate in the open air a few species of +Noctuellae, whose larvae live buried in the earth, are always abundant. The +country is relatively rich in spices of _Tortrix_, which develop and +hibernate in the stalks or roots of plants. It is also worthy of remark +that very few of our species seem to be incapable of enduring a severe +winter.--_C.G. Barret, in Science et Nature_. + + * * * * * + + + + +SILK WORM EGGS. + + +Prof. C.V. Riley, entomologist, announces that the Department of +Agriculture, Washington, will purchase during the coming summer such +quantities of silk worm eggs as may be deemed necessary for the +distribution that it is proposed to make for the season of 1886. So far +as found practicable, the eggs will be purchased of American producers. +There are certain precautions, however, that must be taken to insure +purchase. Eggs of improved races only (preferably of the French or +Italian Yellow Races) will be bought, and the producer should send one or +two samples of pierced cocoons with the eggs. In addition to this the +producer must conform to certain rules to be hereafter explained, so that +an examination may be made that will serve to show the degree of purity +of the eggs. No silk culturist should use his crop for the production of +eggs unless the worms have shown, until they began the spinning of their +cocoons, every sign of perfect, robust health. Any indication of the +disease called _flacherie_, from which the worms so often die after the +fourth moult and turn black from putrefaction, or of any other disease +from which silk worms suffer, should be considered as ample reason for +not using the cocoons for the purpose in question. They should, on the +other hand, be sold for the filature. If the worms have all the +indications of health until the spinning period, then the cocoons may be +used for the production of eggs. The following brief instructions will +prove of service to those who which to secure sound eggs: + +[Illustration] + +For each ounce of eggs to be produced, about three-quarters of a pound of +fresh cocoons from the finest and firmest in the lot should be chosen. +These should be strung in sets upon a thread, care being taken not to +pierce the chrysalis, and the strings hung in a cool, darkened room. The +moths generally emerge from the cocoons early in the morning, and will be +seen crawling about over these, the males being noticeable by their +smaller abdomens, more robust antennae, and by their greater activity. The +moths should be placed, regardless of sex, on a table, where they will +soon find their mates and couple. As soon as formed, the couples should +be removed to another table, that they may not be disturbed by the +flutterings of the single moths. + +There should be prepared for each ounce of eggs to be produced, about +one hundred small bags of fine muslin, made in the following manner: Cut +the cloth in pieces 3x6 inches. Then fold one end over so as to leave a +single edge of about three-quarters of an inch, as shown in the +accompanying cut. This should be sewn up into a bag with the upper end +open, and then turned inside out, so that the seams will cause the sides +to bulge. Thus completed they are called "cells." The cells should be +strung on a cord stretched across the room. + +The moths couple as a rule about eight o'clock in the morning. About four +in the afternoon they should be separated by taking them by the wings and +drawing them gently apart. Each female should now be placed by herself in +a cell, which is then closed by a pin as shown in the figure. Here she +will lay her eggs and in due time die. The males may as a rule be thrown +away, but it is wise to keep a few of the more active ones, in case there +should be a superabundance of females the following day. + +When the females have finished laying their eggs, which operation +occupies about thirty-six hours, they are ready to be shipped to this +office. The cells, with their inclosed moths and eggs, should be placed +in a strong box of wood or tin, being packed in such a manner that they +will not be crushed, and mailed to the entomologist at the department. By +using the inclosed return penalty slip, payment of postage may be +avoided. The name of the sender should be placed in each box. The moths, +as soon as received, will be examined microscopically, and the eggs of +those which are found to be free from disease will be weighed and paid +for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce +avoirdupois). Silk culturists are advised not to attempt the production +of eggs unless they are adepts at the industry, and have had at least one +season's experience. We would advise each person desiring to sell, to +send a sample first, with a statement of the quantity offered. + + * * * * * + + +Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He +intends to bring home phonograms of the savage dialects which he will +hire the natives to speak into the machine. + + * * * * * + +[NATURE.] + + + + +DETERMINING THE MEAN DENSITY OF THE EARTH. + + +In _Nature_ for March 5 (p. 408) Prof. Mayer suggests an improvement in +our method of determining the mean density of the earth, from which it +appears that our plan has not been properly understood. This +misunderstanding, no doubt, has arisen from the incomplete description of +our method given in the _Nature_ (Jan. 15. p. 260) report of the +_Proceedings_ of the Berlin Physical Society, which report was probably +the only source of information accessible to Prof. Mayer. We are led +therefore to give a short description of our method. + +Let H I K L represent a section of a cubical block of lead, about two +meters in the edge, and weighing 100,000 kilos. The balance, A B C, is +placed in the middle of the upper horizontal surface. It bears the +scale-pans, D and E. Under these scale-pans the block is bored vertically +through, and two other scale-pans, F and G, are suspended below the +block, attached to the balance by means of rods passing through these +openings. + +A weight D is brought into equilibrium by weights in G. The weight in D +is acted upon by the earth's attraction + that of the block, and that in +G by the earth's attraction - that of the block. The weights in G are then +greater than that in D by twice the attraction of the block. The weight +in D in now removed to F, and counterbalanced by weights in E. The weight +in E will be less than that in F by twice the attraction of the block. +The difference of the two weighings gives therefore four times the +attraction of the block. A correction must be introduced for the +variation in the earth's attraction due to the different heights of D, E +and F, G. + +[Illustration] + +In order to obtain as great a deflection of the balance by the method +suggested by Prof. Mayer, each of the mercury spheres must exert the same +attraction as our lead block. This would require spheres having radii of +about one meter. The length of the beam of the balance would be +necessarily at least two meters. Besides, each mass of mercury, would +exert some attraction on the weight on the other side, and thus lessen +the deviation of the balance. + +The method given by Prof. Mayer, except for the suggested employment of +mercury, is then no improvement on ours. If we should use mercury, we +would construct a cubical vessel to contain it, and use it as we propose +to use the lead block. The advantage of using mercury is, however, +counterbalanced by the difficulty of obtaining it in such large +quantities as would be necessary. + +ARTHUR KONIG. + +FRANZ RICHARZ. + +Berlin, Physical Institute of the University, March 15. + + * * * * * + + + + +PHYSICS WITHOUT APPARATUS. + + +_The Porosity and Permeability of Bodies._--Take two tumblers of the same +size, place one of them upon a table, and pour into it a small quantity +of nearly boiling water. Cover this glass with a sheet of cardboard, and +invert the other one upon it. This second tumbler must be previously +wiped so as to have it perfectly dry and transparent. In a few seconds +the steam from the lower tumbler will traverse the cardboard (which will +thus exhibit its permeability), and will gradually fill the upper +tumbler, and condense and run down its sides. Wood and cloth may be +experimented with in succession, and will give the same results; but +there are other substances that are _impermeable_, and will not allow +themselves to be traversed. Such, for example, is the vulcanized rubber +of which waterproofs are made. This experiment explains to us why fog +is, as has been well said, so _penetrating_. It traverses the tissue of +our overcoat and of our flannel, and comes into contact with our body. On +the contrary, a rubber coat preserves us against its action. + +[Illustration: Fig. 1.--EXPERIMENT UPON THE PERMEABILITY OF BODIES.] + +_A Hot Air Balloon_.--Make a hollow cylinder of small diameter out of a +sheet of paper such as is used for cigarette packages, and turn in the +ends slightly so that it shall preserve its form. If the cylinder seems +too difficult to make, a cone may be substituted. Now set fire to the +cylinder or cone at its upper part. The paper will burn and become +converted into a thin sheet of ashes, which will contract and curl +inward. This light residuum of ashes, being filled with air rarefied by +combustion, will suddenly rise to a distance of two or three yards. Here +we have a Montgolfier balloon.--_La Nature_. + +[Illustration: Fig. 2.--PRINCIPLE OF THE HOT AIR BALLOON.] + + * * * * * + + + + +THE CASINO AT MONTE CARLO. + + +The little city is situated about half way between Nizza and Mentone, and +it formerly was the chief city of a principality that belonged to the +family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to +the Emperor Napoleon, for three million francs, consequently the land +came under the jurisdiction of the French republic, but the city remained +in the Prince's possession, who, however, gave to the gambler Blanc the +privilege of erecting a gambling house upon the rocky shore of the sea. + +[Illustration: THE CASINO AT MONTE CARLO.] + +Enormous sums of money were spent to give this isolated cliff its present +appearance, covered as it is with beautiful buildings, hotels, and +villas, besides the magnificent Casino building, which was erected in +1862. Directly facing the sea, there is a succession of most beautiful +gardens and terraces. + +But this establishment, which seems like paradise, has had a most +disastrous effect upon thousands of persons, and for a long time the +subject of influencing the French government to put a stop to this +gambling house has been agitated. It can scarcely be imagined how much +misery it has already caused. It is evident to every one that the keeper +of the bank makes considerable profit, as the chances are 63 times +greater in his favor than those of the player. + +It is admitted that the profits amount every year to 17 million francs. +One can well imagine how many fortunes have been consumed every year to +make this profit; but the number cannot be determined. + + * * * * * + + + + +ON AN EXPRESS ENGINE. + + +It is a somewhat unpromising morning--the river is dark with fog and the +huge arch of the station nearly hidden by mist and steam. A cold, damp +wind makes the passengers hurry into the carriages, and strikes us +sharply as we step on to the foot-plate of the engine, which has just +joined the train. But as we get behind the shelter of the screen, we feel +a generous and slightly unctuous sensation of warmth very comforting to a +chilly man. The brasswork of the engine shines brilliantly, the footboard +has been newly scrubbed, and the driver and stoker stand waiting for the +signal. The needle shows that the steam is just below the pressure at +which it would begin to blow off; the water in the gauge glass is just +where it ought to be; in fact, the engine is in perfect condition and +ready for a start. The line is clear, the guard's whistle is answered by +our own, and we glide almost imperceptibly past the last few yards of the +platform. The driver opens the regulator till he is answered by a few +sounding puffs from the funnel, and then stands on the lookout for +signals so numerous that one wonders how he can tell which of the many +waving arms is raised or lowered for his guidance. + +So he goes on, with hand on regulator and lever, gradually admitting more +steam as signal after signal comes nearer and then flies past us, till at +last we are clear of the suburbs and find ourselves on a gentle incline +and a straight road, with the open fields on either side. It is now that +the real business of the journey begins. Locomotives are as sensitive and +have as many peculiarities as horses, and have to be as carefully studied +if you would ride them fast and far. The lever is put into the most +suitable notch for working the steam expansively; the driver's hand is on +the regulator, not to be removed for the rest of the trip; the furnace +door is thrown wide open, and firing begins in earnest. Here it may not +be amiss to state, for the benefit of the uninitiated, that the regulator +controls the supply of steam from the boiler, while the lever enables the +driver to reverse the engine, or, as we have already stated, to expand +the steam by cutting it off before the end of the stroke. The engine +answers to the appeal like a living thing, and seems, with its steady +beat and sonorous blast, to settle down to its work. It is pleasant from +our seat in the corner of the screen to see this preparation for the work +ahead--the absolute calm of driver and stoker, who exchange no word, but +go steadfastly and quietly about their business; to feel the vibrations +from the rails beneath throb through one with slowly increasing rapidity, +or watch the trees and houses go past as gulls flap past a boat. For +there is a certain apparent swagging movement of the objects past which +one travels which can only be likened to the peculiar flight of a large +sea-bird. But now there are signs of increased activity on the +foot-plate; the stoker is busy controlling the feed of water to the +boiler, and fires at more frequent intervals; the driver's hand moves +oftener as he coaxes and encourages the engine along the road, his +slightest gesture betraying the utmost tension of eye and ear; the +stations, instead of echoing a long sullen roar as we go through them, +flash past us with a sudden rattle, and the engine surges down the line, +the train following with hot haste in its wake. We are in a cutting, and +the noise is deafening. Looking ahead, we see an apparently impenetrable +wall before us. Suddenly the whistle is opened, and we are in one of the +longest tunnels in England. The effect produced is the opposite of that +with which we are familiar in a railway carriage, for the change is one +from darkness to light rather than from light to darkness. The front of +the fire-box, foot-plate, and the tender, which had been rather hazily +perceived in the whirl of surrounding objects, now strike sharply on the +eye, lit up by the blaze from the fire, while overhead we see a glorious +canopy of ruddy-glowing steam. The speed is great, and the flames in the +fire-box boil up and form eddies like water at the doors of an opening +lock. Far ahead we see a white speck, which increases in size till the +fierce light from the fire pales, and we are once more in open day. The +weather has lifted, the sky is gray, but there is no longer any +appearance of mist. The hills on the horizon stand out sharply, and seem +to keep pace with us as the miles slip past. The line is clear; but there +is an important junction not far distant, and we slacken speed, to insure +a prompt pull-up should we find an adverse signal. The junction signals +are soon sighted; neither caution nor danger is indicated, and, once +clear of the station, we steam ahead as fast as ever. One peculiarity of +the view of the line ahead strikes us. Looking at a railroad line from a +field or neighboring highway, even where the rails are laid on a steep +incline, the rise and fall of the road is not very strikingly apparent. +Seen through the weather-glass, the track appears to be laid up hill and +down dale, like a path on the downs above high cliffs. Over it all we +advance, the engine laboring and puffing on one or two heavy gradients, +in spite of a full supply of steam, or tearing down the inclines with +hardly any, or none at all and the brake on. And here it may be noted +that, like modern men, modern engines have been put upon diet, and are +not allowed to indulge in so much victual as their forefathers. The +engine-driver, like the doctor of the new school, is determined not to +ruin his patient by over-indulgence, and will tell you severely enough +that "he will never be guilty of choking his engine with an over-supply +of steam." In the mean time, the character of the country we travel +through has changed. It has become more open, and there is a stiff +sea-breeze, which makes itself distinctly felt through the rush of air +produced by the speed at which we are going. We fly past idle streams and +ponds, and as the steam swirls over them are disappointed at producing +so little effect; but the ducks, their inhabitants, are well used to such +visitations, and hardly deign to move a feather. Suddenly we plunge into +a series of small chalk cuttings, and on emerging from them find +ourselves parallel with a grand line of downs. We speed by a curve or +two, and find ourselves on the sea-shore; one more tunnel, and with steam +off we go soberly into the last station. But there is one step more. The +breeze blows about our ears. Before us the rails are wet, for the sea +swept over them not many hours since, and to accomplish the last few +yards of our journey the lever controlling the sand-box must be used +liberally, to prevent slipping; the signal is given, and at a walking +pace we make our way to where the steamer is awaiting us. A gentle +application of the brake pulls us up, and the journey is over. It is +difficult to realize, as the engine stands quietly under the lee of the +pier while the driver examines the machinery, and the fire, burned low, +throws out a gentle warmth as we stand before it, that half an hour ago +we were tearing along the line at full speed, while the foot-plate that +is now so pleasant to lounge on throbbed beneath us. Nothing now remains +but to kill time as best we may till the return trip many hours hence. It +scarcely promises to be as comfortable as our morning ride, for the +weather has changed--it is blowing half a gale, and the rain comes down +in sheets. Our train is timed to start in the small hours, and the night +seems dirty and depressing enough as we make our way for a cup of coffee +to the refreshment room, where a melancholy Italian sits in sad state +eating Bath buns and drinking brandy. We walk past the train, laden with +miserable sea-sick humanity, and step on the engine, which stands in the +dark at the end of the platform. Time is up, and we pass from the dim +half-light of the station into outer darkness. A blacker night there +could hardly be; looking ahead there is nothing to be seen but one's own +reflection in the weather-glass. We are in the midst of obscurity, which +suddenly changes to a rich light as the whistle is opened and we enter a +tunnel. The effect is far more striking than in the daytime. The light is +more concentrated, and the mouth of the tunnel we have just entered might +be the entrance to Hades--for there is no telltale spot of light to prove +to our senses the existence of any opening at the other end. The sound +echoed from the walls and roof has a tremendous quality, and resolves +itself into a grand sort of Wagnerian rhythm, making a vast crescendo, +till with a rush we clear the tunnel, and are once more under the open +sky. The pace is increasing, the steady beat of the engine tells more +distinctly on the ear than in the daytime; the foot-plate is lit up by +the glare from the fire-door; but still there is nothing to be seen ahead +but the impenetrable night. Looking back, however, the scene is very +different. The tender and guard's van glow in the light thrown by the +fire, trees and houses by the side of the track stand out sharply for a +moment and are then lost to sight, the light from the carriage windows +produces the effect of the wake of a ship seen from the stern. Gradually +the clouds have rolled away, leaving the sky clear. The moon is seen +fitfully through the whirling steam; the surrounding country is visible +for miles round. The effect produced is unspeakably beautiful. In the +mean time let us turn our attention to the working of the engine. In the +first place, let us take note that, although the engine we are now on, +and that which took us from London, belong to the same type, their +performances are somewhat different. No two engines ever resemble each +other, no matter how carefully they may have been built from the same +plan, neither do any two drivers manage their engines precisely in the +same way. We have in this instance an excellent opportunity of comparing +two different methods of driving. It is the driver's principal object to +get the required amount of work out of his engine with the smallest +possible expenditure of coal and water. To obtain this result the steam +must be worked expansively, which is done by placing the valve gear in +such a position by means of the lever that the supply of steam to the +cylinders is cut off, as we have stated at the beginning of this article, +before the piston has accomplished its full stroke. There are two ways of +controlling the speed of an engine worked, as all locomotives are worked +now, expansively. You may keep the regulator wide open, so that there is +always a full supply of steam on its way to the cylinders, in which case +you increase or diminish the speed by using the steam more or less +expansively through the agency of the lever. Or you may work with the +same amount of expansion throughout the journey, and have command of the +engine by constantly changing the position of the regulator. There is no +doubt that the men who employ the latter method save something by it, +although this would hardly seem to be the opinion of the driver who is +bringing us rapidly nearer to London, for unlike the driver whom we +accompanied on the daylight journey, his hand is not often on the +regulator. As we rush on past countless signals, punctual to the minute, +yet always having ample time to slacken speed before we come to the +places where the different colored lights cluster thickest, we are +reminded once more how much is required of an express engine-man besides +a thorough acquaintance with the machinery he has to control. Traveling +at night at a great speed, he must know every inch of the road by +heart--where an incline begins and where it ends, and the exact spot at +which every signal along the line may be first sighted. He must have +completely mastered the working of the traffic on both the up and down +lines, and, above all, must be ready to act with the utmost promptitude +should anything go wrong. Mr. Michael Reynolds' publications have done +much toward enlightening the public on these points, but we doubt if +there are many who really know the amount of toil and danger cheerfully +faced by the men on the engine, who hold their lives in their hands day +after day for many years. These thoughts occur to us as we recross the +Thames and pull up at the platform after a thoroughly enjoyable +run.--_Saturday Review_. + + * * * * * + + +The mucilage on postage stamps may not be unhealthy, but persons having a +good many to affix to letter envelopes, circulars, newspapers, or other +wrappers every day, will consume considerable gum during a year. A less +objectionable mode of affixing stamps than the one usually employed is to +wet the upper right hand corner of the envelope, and press the stamp upon +it. It will be found to adhere quite as well as if the stamp went through +the moistening process. + + * * * * * + + + + +ERYTHROXYLON. + +[Footnote: From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, +and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, +S.B., M.D., and Charles F. Squibb, A.B.] + + +COCA. + +The condition of the principal markets of the world for this drug has +recently been exceptionally bad. That is, whether good coca was sought +for in the ports of Central and South America, or in London, Hamburg, or +New York, the search, even without limitation in price, was almost +invariably unsuccessful. Not that the drug, independent of quality, was +scarce, for hundreds of bales were accessible at all times; but the +quality was so poor as to be quite unfit for use. The samples, instead of +being green and fragrant, were brown and odorless, or musty and +disagreeable, at once condemning the lots they represented, to the most +casual observation, and yet the price was high enough to have represented +a good article. The best that could be done by the most careful buyers +was to accept occasional parcels, the best of which were of very inferior +quality, and therefore unfit for medicinal uses, and these at very high +prices. Coca is well known to be a very sensitive and perishable drug, +only fit for its somewhat equivocal uses when fresh and green, and well +cared for in packing and transportation. Very much like tea in this and +other respects, it should be packed and transported with the same care +and pains, in leaded chests, or in some equivalent package. It is very +well known that tea, if managed, transported, handled, and sold as coca +is, would be nearly or quite worthless, and therefore coca managed as the +great mass of it is must be nearly all of it comparatively worthless. If +used as tea is, this would probably soon appear; but when used as a +medicine which has been highly extolled and well advertised, it seems to +go on equally well whether of good or bad quality. It is pretty safe to +say that nineteen-twentieths of the coca seen in this market within the +past two years must be almost inert and valueless, yet all is sold and +used, and its reputation as a therapeutic agent is pretty well kept up. +At least many thousands of pounds of the brown ill-smelling leaf, and of +preparations made from it, are annually sold. And worse than this, +considerable quantities of a handsome looking green leaf, well put up and +well taken care of, have been sold and used as coca, when wanting in +nearly all its characteristics. + +The writer for more than a year past has seen but one or two small lots +of moderately good coca, and in common with other buyers has been obliged +to buy the best that could be found to keep up his supply of the fluid +extract. Almost every purchase has been made on mental protest, and he +has been ashamed of every pound of fluid extract sent out, from the +knowledge that it was of poor quality; and there seems to be no more +prospect of a supply of better quality than there was this time last +year, because so long as an inferior quality sells in such enormous +quantities at good prices the demands of trade are satisfied. + +Under this condition of the markets, the writer has finally decided to +give up making a fluid extract of coca, and has left it off his list, +adopting a fluid extract of tea instead, as a superior substitute, for +those who may choose to use it, and regrets that this course was not +taken a year ago. + +The character of coca as a therapeutic agent is not very good. The florid +stories of a multitude of travelers and writers, up to and including the +testimony of Dr. Mantegazza, received a considerable support from so good +an authority as Sir Robert Christison, who reported very definite results +from trials made upon himself, and upon several students under his +immediate control and observation; and his results seem to have led to a +very careful and exhaustive series of observations at University College, +London, by Mr. Dowdeswell. This paper, published in _The Lancet_ of April +29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: +Observations on the Properties and Action of the Leaf of the Coca Plant +(Erythroxylon coca), made in the Physiological Laboratory of University +College, by G.F. Dowdeswell, B.A." The results of these investigations +were absolutely negative, and at the close of the work the investigator +says: "Without asserting that it is positively inert, it is concluded +from these experiments that its action is so slight as to preclude the +idea of its having any value either therapeutically or popularly; and it +is the belief of the writer, from observation upon the effect on the +pulse, etc., of tea, milk and water, and even plain water, hot, tepid, +and cold, that such things may, at slightly different temperatures, +produce a more decided effect than even large doses of coca, if taken at +about the temperature of the body." + +Conflicting and contradictory testimony from competent authority is not +uncommon in therapeutics, and the reasons for it are well recognized in +the impossibility of an equality in the conditions and circumstances of +the investigations, and hence the general decision commonly reached is +upon the principle of averages. + +There can hardly be a reasonable doubt that coca, in common with tea and +coffee and other similar articles, has a refreshing, recuperative, and +sustaining effect upon human beings, and when well cultivated, well +cured, and well preserved, so as to reach its uses of good quality and in +good condition, it is at least equal to good tea, and available for +important therapeutic uses. Mr. Dowdeswell supposed that he used good +coca, but it is very easy to see that with any amount of care and pains +he may have been mistaken in this. Had he but used the same parcel of +coca that Sir Robert Christison did, the results of the two observers +would be absolutely incomprehensible; and the results, in the absence of +any testimony on that point, simply prove that the two observers were +using a different article, though under the same name, and possibly with +the same care in selection. On Sir Robert Christison's side of the +question there are many competent observers whose testimony is spread +over many years; while on Mr. Dowdeswell's side there are fewer +observers. But there has been no observer on either side whose researches +have been anything like so thorough, so extended, or so accurate as those +of Mr. Dowdeswell. Indeed, no other account has been met with wherein the +modern methods of precision have been applied to the question at all; the +other testimony being all rather loose and indefinite, often at second or +third hands, or from the narratives of more or less enthusiastic +travelers. But if Mr. Dowdeswell's results be accepted as being +conclusive, the annual consumption of 40,000,000 pounds of coca at a cost +of 10,000,000 dollars promotes this substance to take rank among the +large economic blunders of the age.[9] + +[Footnote 9: An excellent summing up of the character and history of +coca, from which some of the writer's information has been obtained, will +be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article +40.] + +The testimony in regard to the effects of tea, coffee, Paraguay tea, +Guarana and Kola nuts, is all of a similar character to that upon coca. +Each of these substances seems to have come into use independently, in +widely separated countries, to produce the same effects, namely, to +refresh, renew, or sustain the physical and mental organism, and it was a +curious surprise to find, after they had all been thus long used, that +although each came from a different natural order of plants, the same +active principle--namely, caffeine--could be extracted in different +proportions from all. It is now still more curious, however, to find that +for centuries another plant, namely coca, yielding a different principle, +has been in use for similar purposes, the effects of which differ as +little from those of tea, coffee, etc., as these do among themselves. Yet +cocaine is chemically very different from caffeine, simply producing a +similar physiological effect in much smaller doses. All these substances +in their natural condition seem to be identical in their general +physiological effect, but idiosyncrasy, or different individual +impressibility or sensitiveness, causes a different action, as well in +quality as in degree from the different substances, upon some persons. + +In order to throw a little additional light on the comparative activity +of the principal individuals of this group of substances, the following +trials were made. It is generally admitted, and is probably true, that +the same power in these agents which refreshes, recuperates, and sustains +in the condition which needs or requires such effects also counteracts +the tendency to sleep, or produces wakefulness when a tendency to sleep +exists; and, therefore, if a tendency or disposition to sleep could be +prevented by these agents, this tendency might be used as a measure of +their effects when used in varying quantities, and thus measure the +agents against each other for dose or quantitative effect. In this way +the proposition is to first measure coca against tea, then coffee against +guarana, and finally to compare the four agents, using pure caffeine as a +kind of standard to measure by. + +An opportunity for such trials occurred in a healthy individual +sixty-five years old, not habituated to the use of either tea, coffee, +tobacco, or any other narcotic substances, of good physical condition and +regular habits, and not very susceptible or sensitive to the action of +nervines or so-called anti-spasmodics. Quantities of preparations of +valerian, asafoetida, compound spirit of ether, etc., which would yield a +prompt effect upon many individuals seem to have little or no effect upon +him, nor do moderate quantities of wines or spirits stimulate him. That +is to say, he has not a very impressible nervous organization, is not +imaginative, nor very liable to accept results on insufficient or partial +evidence. + +Fully occupied with work, both physical and mental in due proportion, for +more than ten hours every secular day, when evening comes he finds +himself unable to read long on account of a drowsiness supposed to be of +a purely physiological character. With a full breakfast at about 7:30, a +full dinner at about 2:30, and a light evening meal about 7, and no +stimulants, or tea, or coffee at any time, he finds, as a matter of not +invariable but general habit, that by half past 8 drowsiness becomes so +dominant that it becomes almost impossible, and generally impracticable, +to avoid falling asleep in his chair while attempting to read, even +though ordinary conversation be carried on around him. + +The first trial to combat or prevent this drowsiness was made with +caffeine. The first specimen used was a very beautiful article made by +Merck of Darmstadt, and after that by pure specimens made for the +purpose, the two kinds being found identical in effect. + +Commencing with a one grain dose at about 6:30 P.M., on alternate +evenings, leaving the intermediate evenings in order to be sure that the +nightly tendency still persisted, and increasing by half a grain each +alternate evening, no very definite effect was perceived, until the dose +reached 21/2 grains, and this dose simply rendered the tendency to sleep +resistible by effort. After an interval of three evenings, with the +tendency to sleep recurring with somewhat varying force each evening, a +dose of 3 grains was taken, the maximum single dose of the German +Pharmacopoeia. This gave a comfortable evening of restedness, without +sleep or any very strong tendency to it until ten o'clock. Without +anything to counteract sleep, the rule was to read with difficulty by +nine, without much comprehension by quarter past nine, and either be +asleep or go to bed by half past nine. The 3 grain dose of caffeine +repeatedly obviated all this discomfort up to ten o'clock, but did not +prevent the habitual, prompt, and sound sleep, from the time of going to +bed till morning. + +This was the model established, upon and by which to measure all the +other agents, and they were never taken nearer than on alternate +evenings, with occasional longer intervals, especially when the final +doses of record were to be taken. + +The next agent tried in precisely this same way was coca; and knowing +that the quality of that which was attainable was very low, the +commencing dose of the leaf in substance was 2 drachms, or about 8 +grammes. This gave no very definite effect, but 21/2 drachms did give a +definite effect, and a subsequent dose of 21/2 fluid drachms of a well made +fluid extract of coca gave about the same effect as 21/2 grains of +caffeine. Three fluid drachms of the fluid extract were about equivalent +to 3 grains of caffeine. + +Both the coca used and the fluid extract were then assayed by the modern +methods, for the proportion of the alkaloid they contained. + +The only assays of coca that could be found conveniently were those of +Dr. Albert Niemann, of Goslar, given in the _American Journal of +Pharmacy_, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of +Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who +obtained 4 grains of alkaloid from 1,500 grains of coca, which is also +about a quarter of one per cent. These assays were, however, very old, +and made by the old process. The process used by the writer was the more +modern one of Dragendorff slightly modified. It was as follows: + +Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 +grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, +and the mixture boiled for ten minutes. The liquid was filtered off, and +the residue percolated with about 60 c.c. of water. It was then again +stirred into 150 c.c. of boiling water, and was again boiled and +percolated until apparently thoroughly exhausted. The total liquid, +amounting to more than 600 c.c., was evaporated on a water-bath, +commencing with the weaker portions, so that the stronger ones might be +exposed to the heat for the shortest time, until reduced to about 20 c.c. +This liquid extract was transferred to a flask, and vigorously shaken +with 50 c.c. of strong ether. The ether was poured off, as closely as +practicable, into a tared capsule, where it was allowed to evaporate +spontaneously. A second and third portion of ether, each of 50 c.c., were +used in the same way, and the whole evaporated to dryness in the capsule. +A scanty, greenish, oily residue was left in the capsule, in which there +was no appearance of a crystallized alkaloid. The capsule and contents +were then weighed and the weight noted. The oily residue was then +repeatedly washed with small quantities of water, until the washings no +longer affected litmus-paper. The oily matter adhered to the capsule +during this process, no part of it coming off with the washing, and at +the end of the washing the capsule and contents were again dried and +weighed, and the weight subtracted from the original weight. The +difference was taken as the alkaloid cocaine, and it amounted to 0.077 +grm., equal to 0.26 per cent. + +Several preliminary assays were made in reaching this method. Some +authorities recommend the very finely powdered mixture of coca and +magnesia, or coca and lime, to be at once exhausted with ether. Others +recommend that the mixture be made into a paste with water, and after +drying on a water-bath that it be then exhausted with ether. This is +better, but neither of these methods were satisfactory. + +Finally, 30 c.c. of a well made fluid extract of the same coca was +thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the +mixture dried on a water-bath and powdered. This powder was then +exhausted, one part by ether and the other part by chloroform, exactly as +in the method given, both parts giving very slightly higher results. As a +check upon the results, the solution of alkaloid washed out was titrated +with normal solution of oxalic acid. + +From all this it would appear that this inferior coca of the markets, or +rather the best that can be selected from it, yields about the same +proportion of the alkaloid as was obtained by Niemann and Maisch, but it +has been shown that, by the older processes of assay used by them, much +of the alkaloid was probably lost or destroyed, and that much better +results are generally obtained by the modern process. + +Now, since 3 drachms of this coca, or three fluid drachms of its fluid +extract, gave the same physiological, or perhaps therapeutical, effect as +3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of +cocaine, it follows that cocaine is about 6.5 times more effective than +caffeine; but it also follows that the coca accessible, and even the very +best coca, contains very much less of its alkaloid than those articles +which yield caffeine do of that principle. + + * * * * * + + + + +THE MELLOCO. + + +ULLUCUS TUBEROSA.--Early last year two tubers of this plant were received +at Kew from Caracas, and from out of doors in a prepared bed in June. The +result of this experiment, together with a few particulars as to the +esculent properties of the tubers, may be worth recording, as I believe +several gardeners, among them being the Messrs. Sutton, have obtained +tubers of the Ullucus from Kew with a view to giving it a trial. The two +Caracas tubers mentioned above were as large as hens' eggs, rather +longer, and somewhat flattened; the skin was red, as in some potatoes. +These, when placed in heat, rapidly developed shoots, which were removed +as soon as they were strong enough to form cuttings; in this way about a +hundred sturdy young plants were obtained and made ready for planting out +of doors in June. They were planted in a light, sandy, well manured soil +in a position exposed to full sunshine. Here they grew quickly, forming +by the middle of August tufts of shoots and leaves one foot across. They +were earthed up as for potatoes, and the strongest shoots were pegged +down and partly covered with soil, though the latter proved unnecessary. +At this time there were no tubers nor any signs of them. On again +examining the plants in September (about the middle), we were surprised +to find no tubers had yet been formed. The plants were now very strong, +and it was therefore concluded that instead of forming tubers the +strength of the plants had "run to leaves." We gave them up, no further +notice being taken of them till the frost came, when on perceiving that a +frost of four or five degrees did not injure the foliage, we again +examined the plants, and found an abundant crop of tubers just below the +surface of the soil, and varying in size from that of peas to pigeons' +eggs. The plants were left till the haulms had been destroyed by cold, +after which the tubers were gathered. On cooking some of the larger ones +by boiling for half an hour, we found them still rather hard, and with a +flavor of potatoes, almost concealed under a strong earthy taste, quite +disagreeable and soap-like. Considering how short a time these tubers had +had to grow in it is not improbable that their hardness and disagreeable +taste were owing to their being unripe; no doubt young, green potatoes +(these Ullucus tubers were partly green) would be quite as nauseous as +these were. + +[Illustration: MELLOCO TUBERS.] + +We are told that the Ullucus is extensively cultivated in Peru and +Bolivia, in the elevated regions where the common potato also thrives, +and with which the Ullucus is equally popular as a tuber-yielding plant. +In the _Gardeners' Chronicle_ for 1848, p. 862, Mr. J.B. Pentland stated +that the Ullucus "is planted in July or August, the seed employed being +generally the smaller tubers, unfit for food, and is gathered in during +the last week of April. These two periods of the year are the spring and +autumn in the southern hemisphere. The mode of cultivation is in drills, +into which the root is dropped, with a little manure. The climate, even +during the summer season, is severe, scarcely a night passing over +without the streams being frozen over, the sky being in general cloudless +at all periods of the year except during the rainy season (December to +March). Mean temperature about 49 deg.." This information seems to support +the view formed of this plant from its behavior at Kew last year, namely, +that the tubers are formed on the approach of cold weather, and that, so +long as the weather is warm and bright, leaves only are developed. Plants +grown in houses where the temperature has not been allowed to fall below +50 deg. in winter did not form any tubers, although they were in good health. +We found no tubers on the plants grown out of doors till some time after +the return of cold, wet weather. It seems likely that this plant does not +develop tubers unless its existence is threatened by cold; at all events, +such a conclusion seems reasonable from the above statements. + +Possibly a wet and rather cold autumn would be favorable to this plant +and the production of its tubers--such a season, for instance, as would +be most unfavorable for the common potato. It would be worth while +testing the Ullucus for low and cold situations where the potato would +not thrive. There is not much probability of the former ever proving a +substitute for or even a rival to the potato, at least in this country; +but there is room for another good esculent, and the Ullucus is prolific +enough, hardy enough, and, we suppose, when properly grown, palatable +enough to be worthy a trial. In the _Gardeners' Chronicle_ for 1848, p. +828, will be found a most interesting detailed account of experiments +made with this plant in France by M. Louis Vilmorin.--_W. Waston, Kew; +The Gardeners' Chronicle_. + + * * * * * + + +A catalogue, containing brief notices of many important scientific papers +heretofore published in the SUPPLEMENT, may be had gratis at this office. + + + * * * * * + +THE SCIENTIFIC AMERICAN SUPPLEMENT. + +PUBLISHED WEEKLY. + +TERMS OF SUBSCRIPTION, $5 A YEAR. + +Sent by mail, postage prepaid, to subscribers in any part of the United +States or Canada. Six dollars a year, sent, prepaid, to any foreign +country. + +All the back numbers of THE SUPPLEMENT, from the commencement, January 1, +1876, can be had. Price, 10 cents each. + +All the back volumes of THE SUPPLEMENT can likewise be supplied. Two +volumes are issued yearly. 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