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diff --git a/8297-h/8297-h.htm b/8297-h/8297-h.htm new file mode 100644 index 0000000..51ff7f4 --- /dev/null +++ b/8297-h/8297-h.htm @@ -0,0 +1,4175 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta name="generator" content="HTML Tidy, see www.w3.org"> +<meta http-equiv="Content-Type" content= +"text/html; charset=ISO-8859-1"> +<title>The Project Gutenberg eBook of Scientific American +Supplement, June 25, 1881</title> +<style type="text/css"> +<!-- +body {margin-left: 15%; margin-right: 15%; background-color: white} +img {border: 0;} +h1,h2,h3 {text-align: center;} +.ind {margin-left: 10%; margin-right: 10%;} +hr {text-align: center; width: 50%;} +.ctr {text-align: center;} +--> +</style> +</head> +<body> + + +<pre> + +Project Gutenberg's Scientific American Supplement, No. 286, 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. 286 + June 25, 1881 + +Author: Various + +Posting Date: October 10, 2012 [EBook #8297] +Release Date: June, 2005 +First Posted: July 4, 2003 + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN SUPPL., NO. 286 *** + + + + +Produced by Olaf Voss, Don Kretz, Juliet Sutherland, Charles +Franks and the Online Distributed Proofreading Team. + + + + + + +</pre> + + + +<p class="ctr"><a href="images/1a.png"><img src= +"images/1a_th.png" alt=""></a></p> + +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 286</h1> + +<h2>NEW YORK, JUNE 25, 1881</h2> + +<h4>Scientific American Supplement. Vol. XI, No. 286.</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.--One Thousand Horse +Power Corliss Engine. 5 figures, to scale, illustrating the +construction of the new one thousand horse power Corliss engine, by +Hitch, Hargreaves & Co.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#2">Opening of the New Workshop of the Stevens +Institute of Technology. Speech of Prof. R.W. Raymond, speech of +Mr. Horatio Allen.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#3">Light Steam Engine for Aeronautical Purposes. +Constructed for Capt. Mojoisky, of the Russian Navy.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#4">Complete Prevention of Incrustation in Boilers. +Arrangement for purifying boiler water with lime and carbonate of +soda.--The purification of the water.--Examination of the purified +water.--Results of water purification.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#5">Eddystone Lighthouse. Progress of the +work.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#6">Rolling Mill for Making Corrugated Iron. 1 figure. +The new mill of Schultz, Knaudt & Co., of Essen, +Germany.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#7">Railway Turntable in the Time of Louis XIV. 1 +figure. Pleasure car. Railway and turntable at Mary-le-Roy Chateau, +France, in 1714.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#8">New Signal Wire Compensator. Communication from A. +Lyle, describing compensators in use on the Nizam State Railway, +East India.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#9">Tangye's Hydraulic Hoist. 2 figures.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#10">Power Loom for Delicate Fabrics. 1 +figure.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#11">How Veneering is Made.</a></td> +</tr> + +<tr> +<td valign="top">II.</td> +<td><a href="#12">TECHNOLOGY AND CHEMISTRY.--The Constituent Parts +of Leather. The composition of different leathers exhibited at the +Paris Exhibition.--Amount of leather produced by different tonnages +of 100 pounds of hides.--Percentage of tannin absorbed under +different methods of tanning.--Amounts of gelatine and tannin in +leather of different tonnages, etc.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#13">Progress in American Pottery.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#14">Photographic Notes.--Mr. Waruerke's New +Discovery.--Method of converting negatives directly into +positives.--Experiments of Capt. Bing on the sensitiveness of coal +oil--Bitumen plates.--Method of topographic engraving. By +Commandant DE LA NOE.--Succinate of Iron Developer.--Method of +making friable hydro-cellulose.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#15">Photo-Tracings in Black and Color.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#16">Dyeing Reds with Artificial Alizarin. By M. +MAURICE PRUD'HOMME.</a></td> +</tr> + +<tr> +<td valign="top">III.</td> +<td><a href="#17">ELECTRICITY, PHYSICAL SCIENCE, ETC.--On Faure's +Secondary Battery.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#18">Physical Science in Our Common Schools.--An +exceptionally strong argument for the teaching of physical science +by the experimental method in elementary schools, with an outline +of the method and the results of such teaching.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#19">On the Law of Avogadro and Ampere. By E. +VOGEL.</a></td> +</tr> + +<tr> +<td valign="top">IV.</td> +<td><a href="#20">GEOGRAPHY, GEOLOGY, ETC.--Petroleum and Coal in +Venezuela.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#21">Geographical Society of the Pacific.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#22">The Behring's Straits Currents.--Proofs of their +existence.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#23">Experimental Geology.--Artificial production of +calcareous pisolites and oolites.--On crystals of anhydrous +lime.--4 figures.</a></td> +</tr> + +<tr> +<td valign="top">V.</td> +<td><a href="#24">NATURAL HISTORY, ETC.--Coccidæ. By Dr. H. +BEHR.--An important paper read before the California Academy of +Sciences.--The marvelous fecundity of scale bugs.--Their +uses.--Their ravages.--Methods of destroying them.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#25">Agricultural Items.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#26">Timber Trees.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#27">Blood Rains.</a></td> +</tr> + +<tr> +<td valign="top">VI.</td> +<td><a href="#28">MEDICINE AND HYGIENE.--Medical Uses of +Figs.</a></td> +</tr> + +<tr> +<td></td> +<td><a href="#29">Topical Medication in Phthisis.</a></td> +</tr> + +<tr> +<td valign="top">VII.</td> +<td><a href="#30">ARCHITECTURE, ETC.--Suggestions in +Architecture.--Large illustration.--The New High School for Girls, +Oxford, England.</a></td> +</tr> +</table> + +<hr> +<p><a name="20"></a></p> + +<h2>PETROLEUM AND COAL IN VENEZUELA.</h2> + +<p>MR. E. H. PLUMACHER, U. S. Consul at Maracaibo, sends to the +State Department the following information touching the wealth of +coal and petroleum probable in Venezuela:</p> + +<p>The asphalt mines and petroleum fountains are most abundant in +that part of the country lying between the River Zulia and the +River Catatumbo, and the Cordilleras. The wonderful sand-bank is +about seven kilometers from the confluence of the Rivers Tara and +Sardinarte. It is ten meters high and thirty meters long. On its +surface can be seen several round holes, out of which rises the +petroleum and water with a noise like that made by steam vessels +when blowing off steam, and above there ascends a column of vapor. +There is a dense forest around this sand-bank, and the place has +been called "El Inferno." Dr. Edward McGregor visited the +sand-bank, and reported to the Government that by experiment he had +ascertained that one of the fountains spurted petroleum and water +at the rate of 240 gallons per hour. Mr. Plumacher says that the +petroleum is of very good quality, its density being that which the +British market requires in petroleum imported from the United +States. The river, up to the junction of the Tara and Sardinarte, +is navigable during the entire year for flat-bottomed craft of +forty or fifty tons.</p> + +<p>Mr. Plumacher has been unable to discover that there are any +deposits of asphalt or petroleum in the upper part of the +Department of Colon, beyond the Zulia, but he has been told that +the valleys of Cucuta and the territories of the State of Tachira +abound in coal mines. There are coal mines near San Antonia, in a +ravine called "La Carbonera," and these supply coal for the smiths' +forges in that place. Coal and asphalt are also found in large +quantities in the Department of Sucre. Mr. Plumacher has seen, +while residing in the State of Zulia, but one true specimen of +"lignite," which was given to him by a rich land-owner, who is a +Spanish subject. In the section where it was found there are +several fountains of a peculiar substance. It is a black liquid, of +little density, strongly impregnated with carbonic acid which it +transmits to the water which invariably accompanies it. Deposits of +this substance are found at the foot of the spurs of the +Cordilleras, and are believed to indicate the presence of great +deposits of anthracite.</p> + +<p>There are many petroleum wells of inferior quality between +Escuque and Bettijoque, in the town of Columbia. Laborers gather +the petroleum in handkerchiefs. After these become saturated, the +oil is pressed out by wringing. It is burned in the houses of the +poor. The people thought, in 1824, that it was a substance unknown +elsewhere, and they called it the "oil of Columbia." At that time +they hoped to establish a valuable industry by working it, and they +sent to England, France, and this country samples which attracted +much attention. But in those days no method of refining the crude +oil had been discovered, and therefore these efforts to introduce +petroleum to the world soon failed.</p> + +<p>The plains of Ceniza abound in asphalt and petroleum. There is a +large lake of these substances about twelve kilometers east of St. +Timoteo, and from it some asphalt is taken to Maracaibo. Many +deposits of asphalt are found between these plains and the River +Mene. The largest is that of Cienega de Mene, which is shallow. At +the bottom lies a compact bed of asphalt, which is not used at +present, except for painting the bottoms of vessels to keep off the +barnacles. There are wells of petroleum in the State of Falcon.</p> + +<p>Mr. Plumacher says that all the samples of coal submitted to him +in Venezuela for examination, with the exception of the "lignite" +before mentioned, were, in his opinion, asphalt in various degrees +of condensation. The sample which came from Tule he ranks with the +coals of the best quality. He believes that the innumerable +fountains and deposits of petroleum, bitumen, and asphalt that are +apparent on the surface of the region around Lake Maracaibo are +proof of the existence below of immense deposits of coal. These +deposits have not been uncovered because the territory remains for +the most part as wild as it was at the conquest.</p> + +<hr> +<p><a name="1"></a></p> + +<h2>ONE THOUSAND HORSE-POWER CORLISS ENGINE.</h2> + +<p class="ctr"><img src="images/1b.png" alt=""></p> + +<p class="ctr">FIG. 1.<br> +<br> +DIA. OF CYLINDER = 40''<br> +STROKE = 10 ft.<br> +REVS = 41<br> +SCALE OF DIAGRAMS 40 LBS = 1 INCH<br> +<br> +FIG. 2.</p> + +<p>We illustrate one of the largest Corliss engines ever +constructed. It is of the single cylinder, horizontal, condensing +type, with one cylinder 40 inches diameter, and 10 feet stroke, and +makes forty-five revolutions per minute, corresponding to a piston +speed of 900 feet per minute. At mid stroke the velocity of the +piston is 1,402 feet per minute nearly, and its energy in foot +pounds amounts to about 8.6 times its weight. The cylinder is steam +jacketed on the body and ends, and is fitted with Corliss valves +and Inglis & Spencer's automatic Corliss valve expansion gear. +Referring to the general drawing of the engine, it will be seen +that the cylinder is bolted directly to the end of the massive cast +iron frame, and the piston coupled direct to the crank by the steel +piston rod and crosshead and the connecting rod. The connecting rod +is 28 feet long center to center, and 12 inches diameter at the +middle. The crankshaft is made of forged Bolton steel, and is 21 +inches diameter at the part where the fly-wheel is carried. The fly +driving wheel is 35 feet in diameter, and grooved for twenty-seven +ropes, which transmit the power direct to the various line shafts +in the mill. The rope grooves are made on Hick, Hargreaves & +Co.'s standard pattern of deep groove, and the wheel, which is +built up, is constructed on their improved plan with separate arms +and boss, and twelve segments in the rim with joints planed to the +true angle by a special machine designed and made by themselves. +The weight of the fly-wheel is about 60 tons. The condensing +apparatus is arranged below, so that there is complete drainage +from the cylinder to the condenser. The air pump, which is 36 +inches diameter and 2 feet 6 inches stroke, is a vertical pump +worked by wrought iron plate levers and two side links, shown by +dotted lines, from the main crosshead. The engine is fenced off by +neat railing, and a platform with access from one side is fitted +round the top of the cylinder for getting conveniently to the valve +spindles and lubricators. The above engraving, which is a side +elevation of the cylinder, shows the valve gear complete. There are +two central disk plates worked by separate eccentrics, which give +separate motion to the steam and exhaust valves. The eccentrics are +mounted on a small cross shaft, which is driven by a line shaft and +gear wheels. The piston rod passes out at the back end of the +cylinder and is carried by a shoe slide and guide bar, as shown +more fully in the detailed sectional elevation through the +cylinder, showing also the covers and jackets in section. The +cylinder, made in four pieces, is built up on Mr. W. Inglis's +patent arrangement, with separate liner and steam jacket casing and +separate end valve chambers. This arrangement simplifies the +castings and secures good and sound ones. The liner has face +joints, which are carefully scraped up to bed truly to the end +valve chambers. The crosshead slides are each 3 feet 3 inches long +and I foot 3 inches wide. The engine was started last year, and has +worked beautifully from the first, without heating of bearings or +trouble of any kind, and it gives most uniform and steady turning. +It is worked now at forty-one revolutions per minute, or only 820 +feet piston speed, but will be worked regularly at the intended 900 +feet piston speed per minute when the spinning machinery is adapted +for the increase which the four extra revolutions per minute of the +engine will give; the load driven is over 1,000 horsepower, the +steam pressure being 50 lb. to 55 lb., which, however, will be +increased when the existing boilers, which are old, come to be +replaced by new. Indicator diagrams from the engines are given on +page 309. The engine is very economical in steam consumption, but +no special trials or tests have been made with it. An exactly +similar engine, but of smaller size, with a cylinder 30 inches +diameter and 8 feet stroke, working at forty-five revolutions per +minute, made by Messrs. Hick, Hargreaves & Co. for Sir Titus +Salt, Sons & Co.'s mill at Saltaire, was tested about two years +ago by Mr. Fletcher, chief engineer of the Manchester Steam Users' +Association, and the results which are given below pretty fairly +represent the results obtained from this class of engine. Messrs. +Hick, Hargreaves & Co. are now constructing a single engine of +the same type for 1,800 indicated horse-power for a cotton mill at +Bolton; and they have an order for a pair of horizontal compound +Corliss engines intended to indicate 3,000 horse-power. These +engines will be the largest cotton mill engines in the +world.--<i>The Engineer</i>.</p> + +<p class="ctr"><a href="images/1c.png"><img src= +"images/1c_th.png" alt= +"1000 HORSE POWER CORLISS ENGINE.--BY HICK. HARGREAVES & CO."> +</a></p> + +<p class="ctr">1000 HORSE POWER CORLISS ENGINE.--BY HICK. +HARGREAVES & CO.</p> + +<p><i>Result of Trials with Saltaire Horizontal Engine on February +14th and 15th, 1878. Trials made by Mr. L.E. Fletcher, Chief +Engineer Steam Users' Association, Manchester.</i></p> + +<p>Engine single-cylinder, with Corliss valves. Inglis and +Spencer's valve gear. Diameter of cylinder. 30in.; stroke, 8ft.; 45 +revolutions per minute.</p> + +<pre> +No. of trials +Total 1.H.P. +[MB] Mean boiler pressure. +[MP] Mean pressure on piston at beginning of stroke. +[ML] Mean loss between boiler pressure and cylinder. +[MA] Mean average pressure on piston. +[W] Water Per I.H.P. per hour. +[C] Coal per I.H.P. per hour. +<br> +No. of trials Total MB MP ML MA W C + I.H.P. lb lb lb lb lb lb +Trial No. 1. 301.89 46.6 44.11 2.53 21.23 18.373 2.699 +Trial No. 2. 309.66 47.63 44.45 3.18 21.67 17.599 2.561 +Means. 305.775 47.115 44.28 2.855 21.45 17.986 2.630 +</pre> + +<p class="ctr"><a href="images/2a.png"><img src= +"images/2a_th.png" alt= +"1000 HORSE POWER CORLISS ENGINE.--BY HICK, HARGREAVES & CO."> +</a></p> + +<p class="ctr">1000 HORSE POWER CORLISS ENGINE.--BY HICK, +HARGREAVES & CO.</p> + +<p class="ctr"><a href="images/2b.png"><img src= +"images/2b_th.png" alt= +"1000 HORSE POWER CORLISS ENGINE.--BY HICK, HARGREAVES & CO."> +</a></p> + +<p class="ctr">1000 HORSE POWER CORLISS ENGINE.--BY HICK, +HARGREAVES & CO.</p> + +<hr> +<p><a name="2"></a></p> + +<h2>OPENING OF THE NEW WORKSHOP OF THE STEVENS INSTITUTE OF +TECHNOLOGY.</h2> + +<p>In our SUPPLEMENT No. 283 we gave reports of some of the +addresses of the distinguished speakers, and we now present the +remarks of Prof. Raymond and Horatio Allen, Esq.:</p> + +<h3>SPEECH OF PROF. R. W. RAYMOND.</h3> + +<p>A few years ago, at one of the meetings of our Society of Civil +Engineers we spent a day or so in discussing the proper mode of +educating young men so as to fit them for that profession. It is a +question that is reopened for us as soon as we arrive at the age +when we begin to consider what career to lay out for our sons. When +we were young, the only question with parents in the better walks +of life was, whether their sons should be lawyers, physicians, or +ministers. Anything less than a professional career was looked upon +as a loss of caste, a lowering in the social scale. These things +have changed, now that we engineers are beginning to hold up our +heads, as we have every reason to do; for the prosperity and +well-being of the great nations of the world are attributable, +perhaps, more to our efforts than to those of any other class. +When, in the past, the man of letters, the poet, the orator, +succeeded, by some fit expression, by some winged word, to engage +the attention of the world concerning some subject he had at heart, +the highest praise his fellow man could bestow was to cry out to +him, "Well said, well said!" But now, when, by our achievements, +commerce and industry are increased to gigantic proportions, when +the remotest peoples are brought in ever closer communication with +us, when the progress of the human race has become a mighty +torrent, rushing onward with ever accelerating speed, we glory in +the yet higher praise, "Well done, well done!" Under these +circumstances, the question how a young man is best fitted for our +profession has become one of increasing importance, and three +methods have been proposed for its solution. Formerly the only +point in debate was whether the candidate should go first to the +schools and then to the workshop, or first to the shop and then to +the schools. It was difficult to arrive at any decision; for of the +many who had risen to eminence as engineers, some had adopted one +order and some the other. There remained a third course, that of +combining the school and the shop and of pursuing simultaneously +the study of theory and the exercise of practical manipulation. +Unforeseen difficulties arose, however, in the attempt to carry out +this, the most promising method. The maintenance of the shop proved +a heavy expense, which it was found could not be lessened by the +manufacture of salable articles, because the work of students could +not compete with that of expert mechanics. It would require more +time than could be allotted, moreover, to convert students into +skilled workmen. Various modifications of this combination of +theory and practice, including more or less of the Russian system +of instruction in shop-work, have been tried in different schools +of engineering, but never under so favorable conditions as the +present. With characteristic caution and good judgment, President +Morton has studied the operation of the scheme of instruction +adopted in the Stevens Institute, and, noting its deficiencies, has +now supplied them with munificent liberality, giving to it a +completeness that leaves seemingly nothing that could be improved +upon, even in a prayer or a dream. Still, no one will be more ready +to admit than he who has done all this, that it is not enough to +fit up a machine shop, be it never so complete, and light it with +an electric lamp. The decision as to its efficiency must come from +the students that are so fortunate as to be admitted to it. If such +young men, earnest, enthusiastic, with every incentive to exertion +and every advantage for improvement, here, where they can feel the +throbbing of the great heart of enterprise, within sight of bridges +upon which their services will be needed, within hearing of the +whistles of a score of railroads, and the bells of countless +manufactories which will want them; if such as these, trained under +such instructors and amid such surroundings, prove to be not fitted +for the positions waiting for them to fill, it will have been +definitely demonstrated that the perfect scheme is yet unknown.</p> + +<h3>SPEECH OF MR. HORATIO ALLEN.</h3> + +<p>Impressed with the very great step in advance which has been +inaugurated here this evening, I feel crowding upon me so many +thoughts that I cannot make sure that, in selecting from them, I +may not leave unsaid much that I should say, and say some things +that I had better omit. Some years ago, when asked by a wealthy +gentleman to what machine-shop he had best send his son, who was to +become a mechanical engineer, I advised him not to send him to any, +but to fit up a shop for him where he could go and work at what he +pleased without the drudgery of apprenticeship, to put him in the +way of receiving such information as he needed, and especially to +let him go where he could see things break. Great, indeed, are the +advantages of those who have the opportunity of seeing things +break, of witnessing failures and profiting by them. When men have +enumerated the achievements of those most eminent in our profession +the thought has often struck me, "Ah! if we could only see that +man's scrap heap."</p> + +<p>There are many who are able to construct a machine for a given +purpose so that it will work, but to do this so that it will not +cost too much is an entirely different problem. To know what to +omit is a rare talent. I once found a young man who could tell +students what to store up in their minds for immediate use, and +what to skim over or omit; but I could not keep him long, for more +lucrative positions are always waiting for such men.</p> + +<p>The advice I gave my wealthy friend was given before the Stevens +Institute had developed in the direction it has now. The foundation +of this advice, namely, to combine a certain amount of judicious +practice with theory, is now in a fair way to be carried out, and +although things will probably not be permitted to break here, the +students will doubtless have opportunities for looking around them +and supplementing their systematic instruction here by observation +abroad.</p> + +<hr> +<p><a name="3"></a></p> + +<h2>LIGHT STEAM ENGINE FOR BALLOONS.</h2> + +<p>We here illustrate one of a couple of compound engines designed +and constructed by Messrs. Ahrbecker, Son & Hamkens, of +Stamford Street, S.E., for Captain Mojaisky, of the Russian +Imperial Navy, who intends to use them for aeronautical purposes. +The larger of these engines has cylinders 3¾ in. and +7½ in. in diameter and 5 in. stroke, and when making 300 +revolutions per minute it develops 20 actual horse power, while its +weight is but 105 lbs. The smaller engine--the one illustrated--has +cylinders 2½ in. and 5 in. in diameter, and 3½ in. +stroke, and weighs 63 lbs., while when making 450 revolutions it +develops 10 actual horse power.</p> + +<p>The two engines are identical in design, and are constructed of +forged steel with the exception of the bearings, connecting-rods, +crossheads, slide valves and pumps, which are of phosphor-bronze. +The cylinders, with the steam passages, etc., are shaped out of the +solid. The standards, as will be seen, are of very light T steel, +the crankshafts and pins are hollow, as are also the crosshead +bolts and piston rods. The small engine drives a single-acting air +pump of the ordinary type by a crank, not shown in the drawing. The +condenser is formed of a series of hollow gratings.</p> + +<p class="ctr"><a href="images/3a.png"><img src= +"images/3a_th.png" alt= +"LIGHT STEAM ENGINE FOR AERONAUTICAL PURPOSES"></a></p> + +<p class="ctr">LIGHT STEAM ENGINE FOR AERONAUTICAL PURPOSES</p> + +<p>Steam is supplied to the two engines by one boiler of the +Herreshoff steam generator type, with certain modifications, +introduced by the designers, to insure the utmost certainty in +working. It is of steel, the outside dimensions being 22 in. in +diameter, 25 in. high, and weighs 142 lb. The fuel used is +petroleum, and the working pressure 190 lb. per square inch.</p> + +<p>The constructors consider the power developed by these engines +very moderate, on account of the low piston speed specified in this +particular case. In some small and light engines by the same makers +the piston speed is as high as 1000 ft. per minute. The engines now +illustrated form an interesting example of special designing, and +Messrs. Ahrbecker, Son, and Hamkens deserve much credit for the +manner in which the work has been turned out, the construction of +such light engines involving many practical +difficulties,--<i>Engineering.</i></p> + +<hr> +<p>Mount Baker, Washington Territory, has shown slight symptoms of +volcanic activity for several years. An unmistakable eruption is +now in progress.</p> + +<hr> +<p><a name="4"></a></p> + +<h2>COMPLETE PREVENTION OF INCRUSTATION IN BOILERS.</h2> + +<p>The chemical factory, Eisenbuettel, near Braunschweig, +distributes the following circular: "The principal generators of +incrustation in boilers are gypsum and the so-called bicarbonates +of calcium and magnesium. If these can be taken put of the water, +before it enters the boiler, the formation of incrustation is made +impossible; all disturbances and troubles, derived from these +incrustations, are done away with, and besides this, a considerable +saving of fuel is possible, as clear iron will conduct heat quicker +than that which is covered with incrustation."</p> + +<p>J. Kolb, according to <i>Dingler's Polyt. Journal</i>, says: "A +boiler with clear sides yielded with 1 kil. coal 7.5 kil. steam, +after two months only 6.4 kil. steam, or a decrease of 17 per cent. +At the same time the boiler had suffered by continual working."</p> + +<p>Suppose a boiler free from inside crust would yield a saving of +only 5 per cent. in fuel (and this figure is taken very low +compared with practical experiments) it would be at the same time a +saving of 3c. per cubic meter water. If the cleaning of one cubic +meter water therefore costs less than 3c., this alone would be an +advantage.</p> + +<p>Already, for a long time, efforts have been made to find some +means for this purpose, and we have reached good results with lime +and chloride of barium, as well as with magnesia preparations. But +these preparations have many disadvantages. Corrosion of the +boiler-iron and muriatic acid gas have been detected. (Accounts of +the Magdeburg Association for boiler management.)</p> + +<p>Chloride of calcium, which is formed by using chloride of +barium, increases the boiling point considerably, and diminishes +the elasticity of steam; while the sulphate of soda, resulting from +the use of carbonate of soda, is completely ineffectual against the +boiler iron. It increases the boiling point of water less than all +other salts, and diminishes likewise the elasticity of steam +(Wullner).</p> + +<p>In using magnesia preparation, the precipitation is only very +slowly and incompletely effected--one part of the magnesia will be +covered by the mire and the formed carbonate of magnesia in such a +way, that it can no more dissolve in water and have any effect +(<i>Dingler's Polyt. Journal</i>, 1877-78).</p> + +<p>The use of carbonate of soda is also cheaper than all other +above mentioned substances.</p> + +<p>One milligramme equivalent sulphate of lime, in 1 liter, = 68 +grammes sulphate of lime in 1 cubic meter, requiring for +decomposition:</p> + +<p>120 gr. (86-88 per cent.) chloride of barium of commerce--at +$5.00 = 0.6c.</p> + +<p>Or, 50 gr. magnesia preparation--at $10.00 = 0.5c.</p> + +<p>Or, 55 gr. (96-98 per cent.) carbonate of soda--at $7.50 = +0.41c.</p> + +<p>The proportions of cost by using chloride of barium, magnesia +preparation, carbonate of soda, will be 6 : 5 : 4.</p> + +<h3>ARRANGEMENT FOR PURIFYING BOILER-WATER WITH LIME AND CARBONATE +OF SODA.</h3> + +<p>We need for carrying out these manipulations, according to the +size of the establishment, one or more reservoirs for precipitating +the impurities of the water, and one pure water reservoir, to take +up the purified water; from the latter reservoir the boilers are +fed. The most practical idea would be to arrange the precipitating +reservoir in such manner that the purified water can flow directly +into the feeding reservoir.</p> + +<p>The water in the precipitating reservoir is heated either by +adding boiling water or letting in steam up to 60° C. at least. +The precipitating reservoirs (square iron vessels or horizontal +cylinders--old boilers) of no more than 4 or 4½ feet, having +a faucet 6 inches above the bottom, through which the purified +water is drawn off, and another one at the bottom of the vessel, to +let the precipitate off and allow of a perfect cleaning. In a +factory with six or seven boilers of the usual size, making +together 400 square meters heating surface, two precipitating +reservoirs, of ten cubic meters each, and one pure water reservoir +of ten or fifteen cubic meter capacity, are used.</p> + +<p>In twenty-four hours about 240 cubic meters of water are +evaporated; we have, therefore, to purify twenty-four precipitating +reservoirs at ten cubic meters each day, or ten cubic meters each +hour.</p> + +<p>It is profitable to surround the reservoirs with inferior +conductors of heat, to avoid losses.</p> + +<p>The contents of the precipitating reservoirs have to be stirred +up very well, and for this purpose we can either arrange a +mechanical stirrer or do it by hand, or the best would be a +"Korting steam stirring and blowing apparatus." In using the latter +we only have to open the valve, whereby in a very short time the +air driven through the water stirs this up and mixes it thoroughly +with the precipitating ingredients. In a factory where boilers of +only 15 to 100 square meters heating surface are, one precipitating +reservoir of two to ten cubic meters and one pure water reservoir +of three to ten cubic meters capacity are required. For +locomobiles, two wooden tubs or barrels are sufficient.</p> + +<h3>THE PURIFICATION OF THE WATER.</h3> + +<p>After the required quantity of lime and carbonate of soda which +is necessary for a total precipitation has been figured out from +the analysis of the water, respectively verified by practical +experiments in the laboratory, the heated water in the reservoir is +mixed with the lime, in form of thin milk of lime, and stirred up; +we have to add so much lime, that slightly reddened litmus paper +gives, after ¼ minute's contact with this mixture, an +alkaline reaction, i.e., turns blue; now the solution of carbonate +of soda is added and again stirred well.</p> + +<p>After twenty or thirty minutes (the hotter the water, the +quicker the precipitation) the precipitate has settled in large +flocks at the bottom, and the clear water is drawn off into the +pure water reservoir. The precipitating and settling of the +impurities can also take place in cold water; it will require, +however, a pretty long time.</p> + +<p>In order to avoid the weighing and slaking of the lime, which is +necessary for each precipitation, we use an open barrel, in which a +known quantity of slaked lime is mixed with three and a half or +four times its weight of water, and then diluted to a thin paste, +so that one kilogramme slaked lime is diluted to twenty-five liters +milk of lime.</p> + +<p>Example.--If we use for ten cubic meters water, one kilogramme +lime, or in one day (in twenty-four hours), 240 cubic meters 24 kg. +lime, a vessel four or five feet high and about 700 liters +capacity, in which daily 24 kg. lime with about 100 liters water +are slaked and then diluted to the mark 600, constantly stirring, +25 liters of this mixture contain exactly 1 kg. slaked lime.</p> + +<p>Before using, this milk of lime has to be stirred up and allowed +to settle for a few seconds; and then we draw off the required +quantity of milk of lime (in our case 25 liters) through a faucet +about 8 inches above the bottom, or we can dip it off with a pail. +For the first precipitate we always need the exact amount of milk +of lime, which we have figured out, or rather some more, but for +the next precipitates we do not want the whole quantity, but always +less, as that part of the lime, which does not settle with the +precipitate, will be good for use in further precipitations. It is +therefore important to control the addition of milk of lime by the +use of litmus paper. If we do not add enough lime, it prevents the +formation of the flocky precipitate, and, besides, more carbonate +of soda is used. By adding too much lime, we also use more +carbonate of soda in order to precipitate the excess of lime. We +can therefore add so much lime, that there is only a very small +excess of hydrous lime in the water, and that after well stirring, +a red litmus paper being placed in the water for twenty seconds, +appears only slightly blue. After a short time of practice, an +attentive person can always get the exact amount of lime which +ought to be added. On adding the milk of lime, we have to dissolve +the required amount of pure carbonate of soda in an iron kettle, in +about six or eight parts hot water with the assistance of steam; +add this to the other liquid in the precipitating reservoirs and +stir up well. The water will get clear after twenty-five or thirty +minutes, and is then drawn off into the pure water reservoir.</p> + +<h3>EXAMINATION OF WATER WHICH HAS BEEN PURIFIED BY MEANS OF MILK +OF LIME AND CARBONATE OF SODA.</h3> + +<p>In order to be convinced that the purification of the water has +been properly conducted, we try the water in the following manner. +Take a sample of the purified water into a small tumbler, and add a +few drops of a solution of oxalate of ammonia; this addition must +neither immediately nor after some minutes cause a milky appearance +of the water, but remain bright and clear. A white precipitate +would indicate that not enough carbonate of soda had been added. A +new sample is taken of the purified water and a solution of +chloride of calcium added; a milky appearance, especially after +heating, would show that too much carbonate of soda had been +added.</p> + +<h3>RESULTS OF THIS WATER PURIFICATION.</h3> + +<p>1. The boilers do not need to be cleaned during a whole season, +as they remain entirely free from incrustation; it is only required +to avoid a collection of soluble salts in the boiler, and therefore +it is partly drawn off twice a week.</p> + +<p>2. The iron is not touched by this purified water. The water +does not froth and does not stop up valves. The fillings in the +joints of pipes, etc., do not suffer so much, and therefore keep +longer.</p> + +<p>3. The steam is entirely free from sour gases.</p> + +<p>4. The production of steam is easier and better.</p> + +<p>5. A considerable saving of fuel can soon be perceived.</p> + +<p>6. The cost of cleaning boilers from incrustation, and loss of +time caused by cleaning, is entirely done with. Old incrustations, +which could not be cleaned out before, get decomposed and break off +in soft pieces.</p> + +<p>7. The cost of this purification is covered sufficiently by the +above advantages, and besides this, the method is cheaper and surer +than any other.</p> + +<p>The chemical factory, Eisenbuettel, furnishes pure carbonate of +soda in single packages, which exactly correspond with the +quantity, stated by the analysis, of ten cubic meters of a certain +water. The determination of the quantities of lime and carbonate of +soda necessary for a certain kind of water, after sending in a +sample, will be done without extra charge.--<i>Neue Zeitung fur +Ruebenzucker Industrie</i>.</p> + +<hr> +<p><a name="5"></a></p> + +<h2>EDDYSTONE LIGHTHOUSE.</h2> + +<p>The exterior work on the new Eddystone Lighthouse is about two +thirds done. In the latter part of April fifty-three courses of +granite masonry, rising to the height of seventy feet above high +water, had been laid, and thirty-six courses remained to be set. +The old lighthouse had been already overtopped. As the work +advances toward completion the question arises: What shall be done +with John Smeaton's famous tower, which has done such admirable +service for 120 years? One proposition is to take it down to the +level of the top of the solid portion, and leave the rest as a +perpetual memorial of the great work which Smeaton accomplished in +the face of obstacles vastly greater than those which confront the +modern architect. The London <i>News</i> says: "Were Smeaton's +beautiful tower to be literally consigned to the waves, we should +regard the act as a national calamity, not to say scandal; and, if +public funds are not available for its conservation, we trust that +private zeal and munificence may be relied on to save from +destruction so interesting a relic. It certainly could not cost +much to convey the building in sections to the mainland, and there, +on some suitable spot, to re-erect it as a national tribute to the +genius of its great architect." When the present lighthouse was +built one of the chief difficulties was in getting the building +materials to the spot. They were conveyed from Millbay in small +sailing vessels, which often beat about for days before they could +effect a landing at the Eddystone rocks, so that each arrival +called out the special gratitude of Smeaton.</p> + +<hr> +<p><a name="6"></a></p> + +<h2>ROLLING-MILL FOR MAKING CORRUGATED IRON.</h2> + +<p>MESSRS. SCHULZ, KNAUDT & Co., of Essen, who are making an +application of corrugated iron in the construction of the interior +flues of steam boilers, have devised a new mill for the manufacture +of this form of iron plates, and which is represented in the +accompanying cut, taken from the <i>Deutsche Industrie Zeitung</i>. +The supports of the two accessory cylinders, F F, rest on two +slides, G G, which move along the oblique guides, H H. As a +consequence of this arrangement, when the cylinders, F F, are +caused to approach the cylinder, D, both are raised at the same +instant.</p> + +<p>When the cylinders, F, occupy the position represented in the +engraving by unbroken lines, the flat plate, O, is simply submitted +to pressure between the cylinders, D and P, the cylinders, F F, +then merely acting as guides. But when, while the plate is being +thus flattened between the principal cylinders, the accessory +cylinders are caused to rise, the plate is curved as shown by the +dotted lines, O' O'. To obtain a uniformity in the position of the +two cylinders, F F, the following mechanism is employed: Each +cylinder has an axle, to which is affixed a crank, Q, connected by +means of a rod, R, with the slide, G. These axles are also provided +with toothed sectors, L L, which gear with two screws, L L, whose +threads run in opposite directions. These screws are mounted on a +shaft, N, which may be revolved by any suitable arrangement.</p> + +<p class="ctr"><a href="images/4a.png"><img src= +"images/4a_th.png" alt= +"ROLLING MILL FOR MAKING CORRUGATED IRON"></a></p> + +<p class="ctr">ROLLING MILL FOR MAKING CORRUGATED IRON</p> + +<hr> +<p><a name="7"></a></p> + +<h2>RAILWAY TURN-TABLE IN THE TIME OF LOUIS XIV.</h2> + +<p>The small engraving which we reproduce herewith from <i>La +Nature</i> is deposited at the Archives at Paris. It is catalogued +in the documents relating to Old Marly, 1714, under number 11,339, +Vol. 1. The design represents a diversion called the <i>Jeu de la +Roulette</i> which was indulged in by the royal family at the +sumptuous and magnificent chateau of Mary-le-Roi.</p> + +<p class="ctr"><a href="images/4b.png"><img src= +"images/4b_th.png" alt= +"PLEASURE CAR; RAILWAY AND TURN-TABLE OF THE TIME OF LOUIS XIV."> +</a></p> + +<p class="ctr">PLEASURE CAR; RAILWAY AND TURN-TABLE OF THE TIME OF +LOUIS XIV.</p> + +<p>According to Alex. Guillaumot the apparatus consisted of a sort +of railway on which the car was moved by manual labor. In the car, +which was decorated with the royal colors, are seen seated the +ladies and children of the king's household, while the king himself +stands in the rear and seems to be directing operations. The +remarkable peculiarity to which we would direct the attention of +the reader is that this document shows that the car ran on rails +very nearly like those used on the railways of the present time, +and that a turn-table served for changing the direction to a right +angle in order to place the car under the shelter of a small +building. The picture which we reproduce, and the authenticity of +which is certain, proves then that in the time of Louis XIV. our +present railway turn-tables had been thought of and +constructed--which is a historic fact worthy of being noted. It is +well known that the use of railways in mines is of very ancient +date, but we do not believe that there are on record any documents +as precise as that of the <i>Jeu de la Roulette</i> as to the +existence of turn-tables in former ages.</p> + +<hr> +<p><a name="8"></a></p> + +<h2>NEW SIGNAL WIRE COMPENSATOR.</h2> + +<p><i>To the Editor of the Scientific American</i>:</p> + +<p>I send you a plate of my new railway signal wire compensator. +Here in India signal wires give more trouble, perhaps, than in +America or elsewhere, by expansion and contraction. What makes the +difficulty more here is the ignorance and indolence of the point +and signalmen, who are all natives. There have been numerous +collisions, owing to signals falling off by contraction. Many +devices and systems have been tried, but none have given the +desired result. You will observe the signal wire marked D is +entirely separated and independent of the wire, E, leading to +lever. On the Great Indian and Peninsula Railway I work one of +these compensators, 1,160 yards from signal, which stands on a +summit the grade of which is 1 in 150; and on the Nizam State +Railway I have one working on a signal 800 yards. This signal had +previously given so much trouble that it was decided to do away +with it altogether. It stands on top of a high cutting and on a +1,600 foot curve.</p> + +<p class="ctr"><img src="images/4c.png" alt= +"Railway Signal Wire Comensator"></p> + +<p class="ctr">Railway Signal Wire Comensator</p> + +<p>I have noted on the compensator fixed at 1,160 yards, 13¼ +inches contraction and expansion. The compensator is very simple +and not at all likely to get out of order. On new wire, when I fix +my compensator, I usually have an adjusting screw on the lead to +lever. This I remove when the wire has been stretched to its full +tension. I have everything removed from lever, so there can be no +meddling or altering. When once the wire is stretched so that no +slack remains between lever and trigger, no further adjustment is +necessary.</p> + +<p>A. LYLE,</p> + +<p>Chief Maintenance Inspector, Permanent Way,</p> + +<p>H.H. Nizam State Railway, E. India.</p> + +<p>Secunderabad, India, 1881.</p> + +<p><a name="9"></a></p> + +<h2>TANGYE'S HYDRAULIC HOIST.</h2> + +<p class="ctr"><a href="images/4d.png"><img src= +"images/4d_th.png" alt="TANGYE'S HYDRAULIC HOIST."> +</a></p> + +<p class="ctr">TANGYE'S HYDRAULIC HOIST.</p> + +<p>The great merits of hydraulic hoists generally as regards safety +and readiness of control are too well known to need pointing out +here. We may, therefore, at once proceed to introduce to our +readers the apparatus of this class illustrated in the above +engravings. This is a hoist (Cherry's patent) manufactured by +Messrs. Tangye Brothers, of London and Birmingham, and which +experience has proved to be a most useful adjunct in warehouses, +railway stations, hotels, and the like. Fig. 1 of our engraving +shows a perspective view of the hoist, Fig. 2 being a longitudinal +section. It will be seen that this apparatus is of very simple +construction, the motion of the piston being transmitted directly +to the winding-drum shaft by means of a flexible steel rack. +Referring to Fig. 2, F is a piston working in the cylinder, G; E is +the flexible steel rack connected to the piston, F, and gearing +with a toothed wheel, B, which is inclosed in a watertight casing +having cover, D, for convenient access. The wheel, B, is keyed on a +steel shaft, C, which passes through stuffing-boxes in the casing, +and has the winding barrel, A, keyed on it outside the casing. H is +a rectangular tube, which guides the free end of the flexible steel +rack, E. The hoist is fitted with a stopping and starting valve, by +means of which water under pressure from any convenient source of +supply may be admitted or exhausted from the cylinder. The action +in lifting is as follows: The water pressure forces the piston +toward the end of the cylinder. The piston, by means of the +flexible steel rack, causes the toothed wheel to revolve. The +winding barrel, being keyed on the same shaft as the toothed wheel, +also revolves, and winds up the weight by means of the lifting +chain. Two special advantages are obtained by this simple method of +construction. In the first place, twice the length of stroke can be +obtained in the same space as compared with the older types of +hydraulic hoist; and, from the directness of the action, the +friction is reduced to a minimum. This simple method of +construction renders the hoist very compact and easily fixed; and, +from the directness with which the power is conveyed from the +piston to the winding drum, and the frictionless nature of the +mechanism, a smaller piston suffices than in the ordinary hydraulic +hoists, and a smaller quantity of water is required to work +them.--<i>Iron</i>.</p> + +<hr> +<p><a name="10"></a></p> + +<h2>POWER LOOM FOR DELICATE FABRICS.</h2> + +<p>The force with which the shuttle is thrown in an ordinary power +loom moving with a certain speed is always considerable, and, as a +consequence of the strain exerted on the thread, it is frequently +necessary to use a woof stronger than is desirable, in order that +it may have sufficient resistance. On another hand, when the woof +must be very fine and delicate the fabric is often advantageously +woven on a hand loom. In order to facilitate the manufacture of +like tissues on the power loom the celebrated Swiss manufacturer, +Hanneger, has invented an apparatus in which the shuttle is not +thrown, but passed from one side to the other by means of hooks, by +a process analogous to weaving silk by hand. A loom built on this +principle was shown at work weaving silk at the Paris Exhibition of +1878. This apparatus, represented in the annexed figure, contains +some arrangements which are new and interesting. On each side of +the woof in the heddle there is a carrier, B. These carriers are +provided with hooks, A A', having appendages, <i>a a'</i>, which +are fitted in the shuttle, O. The latter is of peculiar +construction. The upper ends of the hooks have fingers, <i>d +d'</i>, which holds the shuttle in position as long as the action +of the springs, <i>e e'</i>, continues. The distance that the +shuttle has to travel includes the breadth of the heddle, the +length of the shuttle, and about four inches in addition. The +motion of the two carriers, which approach each other and recede +simultaneously, is effected by the levers, C, D, E, and C', D', E'. +The levers, E, E', are actuated by a piece, F, which receives its +motion from the main shaft, H, through the intervention of a crank +and a connecting rod, G, and makes a little more than a quarter +revolution. The levers, E, E', are articulated in such a way that +the motion transmitted by them is slackened toward the outer end +and quickened toward the middle of the loom. While the carriers, B +B', are receiving their alternate backward and forward motion, the +shaft, I (which revolves only half as fast as the main shaft), +causes a lever, F F', to swing, through the aid of a crank, J, and +rod, K. Upon the two carriers, B B', are firmly attached two hooks, +M M', which move with them. When the hook, M, approaches the +extremity of the lever, F, the latter raises it, pushes against the +spring, E, and sets free the shuttle, which, at the same moment, +meets the opposite hook, <i>a'</i>, and, being caught by it, is +carried over to the other side. The same thing happens when the +carrier, B', is on its return travel, and the hook, M', mounts the +lever, F', which is then raised.</p> + +<p class="ctr"><a href="images/5a.png"><img src= +"images/5a_th.png" alt="POWER LOOM FOR DELICATE FABRICS."> +</a></p> + +<p class="ctr">POWER LOOM FOR DELICATE FABRICS.</p> + +<p>As will be seen from this description, the woof does not undergo +the least strain, and may be drawn very gently from the shuttle. +Neither does this latter exert any friction on the chain, since it +does not move on it as in ordinary looms. In this apparatus, +therefore, there may be employed for the chain very delicate +threads, which, in other looms, would be injured by the shuttle +passing over them. Looms constructed on this plan have for some +time been in very successful use in Switzerland.</p> + +<hr> +<p><a name="11"></a></p> + +<h2>HOW VENEERING IS MADE.</h2> + +<p>The process of manufacture is very interesting. The logs are +delivered in the mill yard in any suitable lengths as for ordinary +lumber. A steam drag saw cuts them into such lengths as may be +required by the order in hand; those being cut at the time of our +visit were four feet long. After cutting, the logs are placed in a +large steam box, 15 feet wide, 22 feet long, and six feet high, +built separate from the main building. This box is divided into two +compartments. When one is filled entirely full, the doors are +closed, and the steam, supplied by the engine in the main building, +is turned on. The logs remain in this box from three to four hours, +when they are ready for use. This steaming not only removes the +bark, but moistens and softens the entire log. From the steam box +the log goes to the veneer lathe. It is here raised, grasped at +each end by the lathe centers, and firmly held in position, +beginning to slowly revolve. Every turn brings it in contact with +the knife, which is gauged to a required thickness. As the log +revolves the inequalities of its surface of course first come in +contact with the keen-edged knife, and disappear in the shape of +waste veneer, which is passed to the engine room to be used as +fuel. Soon, however, the unevenness of the log disappears, and the +now perfect veneer comes from beneath the knife in a continuous +sheet, and is received and passed on to the cutting table. This +continues until the log is reduced to about a seven inch core, +which is useless for the purpose. The veneer as it comes rolling +off the log presents all the diversity of colors and the beautiful +grain and rich marking that have perhaps for centuries been growing +to perfection in the silent depths of our great forests.</p> + +<p>From the lathe, the veneer is passed to the cutting table, where +it is cut to lengths and widths as desired. It is then conveyed to +the second story, where it is placed in large dry rooms, air tight, +except as the air reaches them through the proper channels. The +veneer is here placed in crates, each piece separate and standing +on edge. The hot air is then turned on. This comes from the sheet +iron furnace attached to the boiler in the engine room below, and +is conveyed through large pipes regulated by dampers for putting on +or taking off the heat. There is also a blower attached which keeps +the hot air in the dry rooms in constant motion, the air as it +cools passing off through an escape pipe in the roof, while the +freshly heated air takes its place from below. These rooms are also +provided with a net-work of hot air pipes near the floor. The +temperature is kept at about 165°, and so rapid is the drying +process that in the short space of four hours the green log from +the steam box is shaved, cut, dried, packed, and ready for +shipment.</p> + +<p>After leaving the dry rooms it is assorted, counted, and put up +in packages of one hundred each, and tied with cords like lath, +when it is ready for shipment. Bird's-eye maple veneer is much more +valuable and requires more care than almost any other, and this is +packed in cases instead of tied in bundles. The drying process is +usually a slow one, and conducted in open sheds simply exposed to +the air. Mr. Densmore's invention will revolutionize this process, +and already gives his mill a most decided advantage.</p> + +<p>The mill will cut about 30,000 feet of veneer in a day, and this +cut can be increased to 40,000 if necessary. Mr. Densmore has +already received several large orders, and the rapidly increasing +demand for this material is likely to give the mill all the work it +can do. The timber used is principally curled and bird's-eye maple, +beech, birch, cherry, ash, and oak. These all grow in abundance in +this vicinity, and the beautifully marked and grained timber of our +forests will find fitting places in the ornamental uses these +veneers will be put to.</p> + +<hr> +<p><a name="12"></a></p> + +<h2>THE CONSTITUENT PARTS OF LEATHER.</h2> + +<p>The constituent parts of leather seem to be but little +understood. The opinions of those engaged in the manufacture of +leather differ widely on this question.</p> + +<p>Some think that tannin assimilates itself with the hide and +becomes fixed there by reason of a special affinity. Others regard +the hide as a chemical combination of gelatine and tannin. We know +that the hide contains some matters which are not ineradicable, but +only need a slight washing to detach them.</p> + +<p>We deem it advisable, in order to examine the hide properly +so-called, to dispense with those eradicable substances which may +be regarded, to some extent, as not germain to it, and confine our +attention to the raw stock, freed from these imperfections.</p> + +<p>It is well known that a large number of vegetable substances are +employed as tanning agents. Our researches have been directed to +leather tanned by means of the most important of these agents.</p> + +<p>Many questions present themselves in the course of such an +examination. Among others, that most important one, from a +practical point of view, of the weight the tanning agent gives to +the hide, that is to say, the result in leather of weight given to +the raw material. The degree of tannage is also to be considered; +the length of time during which the tanning agent is to be left +with the hide; in short, the influence upon the leather of the +substances used in its production. That is why we have made the +completest possible analysis of different leathers.</p> + +<p>Besides ordinary oak bark there are used at present very +different substances, such as laurel, chestnut, hemlock, quebracho +and pine bark, sumac, etc.</p> + +<p>Water is an element that exists in all hides, and it is +necessary to take it into consideration in the analysis. It is +present in perceptible quantity even in dry hides. This water +cannot be entirely eradicated without injuring the leather, which +will lose in suppleness and appearance. Water should then be +considered as one of the elements of leather, but it must be +understood that if it exceeds certain limits, say 12 to 14 per +cent., it becomes useless and even injurious. Moreover, if there is +any excess over the normal quantity, it becomes deceptive and +dishonest, as in such a case one sells for hides that which is +nothing but water. Supposing that a hide, instead of only 14 per +cent., contained 18 per cent. of water, it is evident that in +buying 100 pounds of such a hide one would pay for four pounds of +water at the rate for which he purchased the hide.</p> + +<p>There are, also, some matters soluble in air, which are formed +to a large extent from fat arising as much from the hide as from +tanning substances. The air dissolves at the same time a certain +amount of organic acid and resinous products which the hide has +absorbed. After treating with air, alcohol is used, which dissolves +principally the coloring matters, tannin which has not become +assimilated, bodies analogous to resin, and some extractive +substances.</p> + +<p>That which remains after these methods have been pursued ought +to be regarded as the hide proper, that is to say, as the animal +tissue saturated with tannic acid. In this remainder one is able to +estimate with close precision that which belongs to the hide. The +hide being an elementary tissue of unchangeable form, it is easy, +in determining the elementary portion, to find the amount of real +hide remaining in the product. With these elements one can arrive +at a solution of some of the questions we are discussing.</p> + +<p>We give below, according to this method, a table showing the +composition of the different leathers exhibited at the Paris +Exposition of 1878. They are the results of careful research, and +we have based our work upon them:</p> + +<pre> + Matter Soluble Fixed + in Air Tannin + | | + | Matter Solu- | + | ble in Alcohol | + | | | + Moisture | | Gelatine | + --+-- --+-- --+-- --+-- --+-- +Steer hide, hemlock tanned (heavy leather) 10.95 4.15 19.77 39.1 26.03 +Sheepskins, sumac " (Hungarian) 10.8 10.3 12.1 40.3 26.5 +Finished calf, pine bark tanned (Hungarian) 11.2 1.7 7.4 41.6 38.1 +Steer hide, quebracho tanned (heavy leather) 11.7 1.6 11.2 43.1 32.4 + " " chestnut " " " 13.5 0.29 1.99 45.46 38.76 +Finished calfskins, + oak tanned (Chateau Renault) 12.4 0.33 3.59 46.74 36.94 +Steer hide, laurel tanned (heavy leather) 12.4 1.05 7.95 47.47 31.13 + " " oak tanned after three years in + the vats (heavy leather) 11.45 0.37 3.31 49.85 35.02 +</pre> + +<p>The following table shows the amount of leather produced by +different tannages of 100 pounds of hides:</p> + +<pre> + Pounds. +Hemlock 255.7 +Sumac 248.1 +Pine 240.3 +Quebracho 232 +Chestnut 219.9 +Oak 213.9 +Laurel 210.6 +Oak, lasting three years 206 +</pre> + +<p>It is important to mention here the large proportion of resinous +matter hemlock-tanned leather contains. This resin is a very +beautiful red substance, which communicates its peculiar color to +the leather.</p> + +<p>We should mention here that in these calculations we assume that +the hide is in a perfectly dry state, water being a changeable +element which does not allow one to arrive at a precise result.</p> + +<p>These figures show the enormous differences resulting from +diverse methods of tanning. Hemlock, which threatens to flood the +markets of Europe, distinguishes itself above all. The high results +attributable to the large proportion of resin that the hide +assimilates, explain in part the lowness of its price, which +renders it so formidable a competitor. One is also surprised at the +large return from sumac-tanned hides when it is remembered in how +short a time the tanning was accomplished, which, in the present +case, only occupied half an hour.</p> + +<p>The figures show us that the greatest return is obtained by +means of those tanning substances which are richest in resin. In +short, hemlock, sumac, and pine, which give the greatest return, +are those containing the largest amount of resin. Thus, hemlock +bark gives 10.58 per cent. of it, and sumac leaves 22.7 per cent., +besides the tannin which they contain. We know also that pine bark +is very rich in resin. There is, then, advantage to the tanner, so +far as the question of result is concerned, in using these +materials. There is, however, another side to the question, as the +leather thus surcharged with resin is of inferior quality, +generally has a lower commercial value, and is often of a color but +little esteemed.</p> + +<p>The percentage of tannin absorbed by the different methods of +tannages appears in the following table:</p> + +<pre> +Hemlock 64.2 +Sumac 61.4 +Pine 90.8 +Quebracho 75.3 +Chestnut 85.2 +Oak 76.9 +Laurel 64.8 +Oak, three years in the vat 70.2 +</pre> + +<p>The subjoined is a statement of the gelatine and tannin in +leather of different tannages, and also shows the amount of azote +or elementary matter contained in each:</p> + +<pre> + Gelatine. Tannin. Azote. +Hemlock 60.4 39.6 10.88 +Sumac 60.4 39.6 11 +Pine bark 52.5 47.5 9.56 +Quebracho 57.1 42.9 10.4 +Chestnut 53.97 46.03 9.79 +Oak 55.87 44.13 10.24 +Laurel 60.4 39.6 10.94 +Oak, 3 years in vat 58.75 41.25 10.65 +</pre> + +<p>It is not pretended that these figures are absolutely correct, +as they often vary in certain limits even for similar products. +They form, however, a fair basis of calculation.</p> + +<p>As to whether leather is a veritable combination, it seems to us +that this question should be answered affirmatively. In fact, the +resistance of leather properly so-called to neutral dissolvents, +argues in favor of this opinion.</p> + +<p>Furthermore, the perceptible proportion of tannin remaining +absorbed by a like amount of hide is another powerful argument. It +remains for us to say here that the differences observable in the +quantity of fixed tannin ought to arise chiefly from the different +natures of these tannins, which have properties differing as do +those of one plant from another, and which really have but one +property in common, that of assimilating themselves with animal +tissues and rendering them imputrescible.</p> + +<p>In conclusion, these researches determine the functions of +resinous matters which frequently accompany tannin; they show a +very simple method for estimating the results of one's work, as +well as the degree of tannage.--<i>Muntz & Schoen, in La Halle +aux Cuirs</i>.--<i>Shoe & Leather Reporter</i>.</p> + +<hr> +<p><a name="30"></a></p> + +<h2>NEW HIGH SCHOOL FOR GIRLS, OXFORD.</h2> + +<p>The new High School for Girls at Oxford, built by Mr. T.G. +Jackson, for the Girls' Public Day School Company, Limited, was +opened September 23, 1880, when the school was transferred from the +temporary premises it had occupied in St. Giles's. The new building +stands in St. Giles's road, East, to the north of Oxford, on land +leased from University College, and contains accommodation for +about 270 pupils in 11 class-rooms, some of which communicate by +sliding doors, besides a residence for the mistress, an office and +waiting-room, a room for the teachers, cloak rooms, kitchens, and +other necessary offices, and a large hall, 50 ft. by 30 ft., for +the general assembling of the school together and for use on +speech-days and other public occasions. The principal front faces +St. Giles's road, and is shown in the accompanying illustration. +The great hall occupies the whole of the upper story of the front +building, with the office and cloak-rooms below it, and the +principal entrance in the center. The class-rooms are all placed in +the rear of the building, to secure quiet, and open on each floor +into a corridor surrounding the main staircase which occupies the +center of the building. The walls are built of Headington stone in +rubble work, with dressings of brick, between which the walling is +plastered, and the front is enriched with cornices and pilasters, +and a hood over the entrance door, all of terra cotta. The hinder +part of the building is kept studiously simple and plain on account +of expense. Behind the school is a large playground, which is +provided with an asphalt tennis-court, and is picturesquely shaded +with apple-trees, the survivors of an old orchard. The builders +were Messrs. Symm & Co., of Oxford; and the terra cotta was +made by Messrs. Doulton, of Lambeth. Mr. E. Long was clerk of +works.--<i>Building News</i>.</p> + +<p class="ctr"><a href="images/6a.png"><img src= +"images/6a_th.png" alt= +"SUGGESTIONS IN ARCHITECTURE--NEW HIGH SCHOOL, OXFORD"></a></p> + +<p class="ctr">SUGGESTIONS IN ARCHITECTURE--NEW HIGH SCHOOL, +OXFORD</p> + +<hr> +<p><a name="13"></a></p> + +<h2>PROGRESS IN AMERICAN POTTERY.</h2> + +<p>No advance in any industry has been more sure than in that of +pottery and chinaware, under the American tariff, or more rapid in +the past four or five years. It took Europe three centuries and the +jealous precautions of royal pottery proprietors to build up the +great protectorates that made their distinctive trade-marks of such +value. The earlier lusters of the Italian faience were guild +privacies or individual secrets, as was almost all the craft of the +earlier art-worker. Royal patronage in England was equivalent to a +protective tariff for Josiah Wedgwood; and everywhere the +importance of guarding the china nurseries has been understood. We +have in this country broadcast and in abundance every type of +material needed for the finest china ware, and for the finer +glasses and enamels. The royal manufactories in Europe were hard +put to it sometimes for want of discovering kaolin beds in their +dominions, but the resources of the United States in these +particulars needed something more than to be brought to light. The +manipulation and washing of the clays to render them immediately +useful to the potteries depends entirely upon the reliance of these +establishments upon home materials. The Missouri potteries have +their supplies near home, but these supplies must be put upon the +market for other cities in condition to compete with the clays of +Europe. There are fine kaolin beds in Chester and Delaware counties +in this State; there are clay beds in New Jersey, and the recent +needs of Ohio potteries have uncovered fine clay in that State. +This shows that not only for the manufacture itself, but for the +development of material here, everything depends upon the stimulus +that protection gives.</p> + +<p>Ohio china and Cincinnati pottery are known all over the +country. The Chelsea Works, near Boston, however, are as +distinguished for their clays and faience, and for lustrous tiles +especially (to be used in household decoration) can rival the rich +show that the Doulton ware made at the Centennial. Other New +England potteries are eminent for terra cotta and granite wares. On +Long Island and in New York city there are porcelain and terra +cotta factories of established fame, and the first porcelain work +to succeed in home markets was made at the still busy factories of +Greenpoint. New Jersey potteries take the broad ground of the +useful, first of all, in their manufacture of excellent granite and +cream-colored ware for domestic use, but every year turn out more +beautiful forms and more artistic work. The Etruria Company +especially have succeeded in giving the warm flesh tints to the +"Parian" for busts and statuettes, now to be seen in many shop +windows. These goods ought always to be labeled and known as +American--it adds to their value with any true connoisseur. Some of +these establishments, more than others, have the enterprise to +experiment in native clays, for which the whole trade owes their +acknowledgments.</p> + +<p>The demand all through the country by skillful decorators for +the pottery forms to work upon, points to still greater extensions +in this business of making our own china, and to the employment and +good pay of more thousands than are now employed in it. A +collection of American china, terra cotta, etc., begun at this time +and added to from year to year, will soon be a most interesting +cabinet. Both in the eastern and western manufactories ingenious +workers are rediscovering and experimenting in pastes and glazes +and colors, simply because there is a large demand for all such, +and they can be supplied at prices within the reach of most buyers. +It needs only to point out this flourishing state of things, +through the "let-alone" principle, which protection insures to this +industry, to exhibit the threatened damage of the attempt, under +cover of earthenware duties, to get a little free trade through at +this session.--<i>Philadelphia Public Ledger</i>.</p> + +<hr> +<p><a name="14"></a></p> + +<h2>PHOTOGRAPHIC NOTES.</h2> + +<p><i>Mr. Warnerke's New Discovery</i>.--Very happily for our art, +we are at the present moment entering upon a stage of improvement +which shows that photography is advancing with vast strides toward +a position that has the possibility of a marvelous future. In +England, especially, great advances are being made. The recent +experiments of our accomplished colleague, Mr. Warnerke, on +gelatine rendered insoluble by light, after it has been sensitized +by silver bromide and developed by pyrogallic acid, have revealed +to us a number of new facts whose valuable results it is impossible +at present to foretell. It seems, however, certain that we shall +thus be able to accomplish very nearly the same effects as those +obtained by bichromatized gelatine, but with the additional +advantage of a much greater rapidity in all the operations. In my +own experiments with the new process of phototypie, I hit upon the +plan of plunging the carbon image, from which all soluble gelatine +had been removed, into a bath of pyrogallic acid, in order to still +further render impermeable the substance forming the printing +surface. I also conceived the idea of afterward saturating this +carbon image with a solution of nitrate of silver, and of +subsequently treating it with pyrogallic acid, in order to still +further render impermeable the substance forming the printing +surface. But the process described by Mr. Warnerke is quite +different; by means of it we shall be able to fix the image taken +in the camera, in the same way as we develop carbon pictures, and +afterward to employ them in any manner that may be desirable. Thus +the positive process of carbon printing would be modified in such a +manner that the mixtures containing the permanent pigment should be +sensitized with silver bromide in place of potassium bichromate. In +this way impressions could be very rapidly taken of positive +proofs, and enlargements made, which might be developed in hot +water, just as in the ordinary carbon process, and at least we +should have permanent images. Mr. Warnerke's highly interesting +experiments will no doubt open the way to many valuable +applications, and will realize a marked progress in the art of +photography.</p> + +<p><i>Method for Converting Negatives Directly into +Positives</i>.--Captain Bing, who is employed in the topographic +studios of the Ministry of War, has devised a process for the +direct conversion of negatives into positives. The idea is not a +new one; but several experimenters, and notably the late Thomas +Sutton, have pointed out the means of effecting this conversion; it +has never, however, so far as I know, been introduced into actual +practice, as is now the case. The process which I am about to +describe is now worked in the studios of the Topographic Service. +The negative image is developed in the ordinary way, but the +development is carried much further than if it were to be used as +an ordinary negative. After developing and thoroughly washing, the +negative is placed on a black cloth with the collodion side +downward, and exposed to diffuse light for a time, which varies +from a few seconds to two or three minutes, according to the +intensity of the plate. Afterward the conversion is effected by +moistening the plate afresh, and then plunging it into a bath which +is thus composed:</p> + +<pre> +Water 700 cub. cents. +Potassium bichromate 30 grams. +Pure nitric acid 300 cub. cents. +</pre> + +<p>In a few minutes this solution will dissolve all the reduced +silver forming the negative; the negative image is therefore +entirely destroyed; but it has served to impress on the sensitive +film beneath it a positive image, which is still in a latent +condition. It must, therefore, be developed, and to do this, the +film is treated with a solution of--</p> + +<pre> +Water 1,000 grams +Pyrogallic acid 25 " +Citric acid 20 " +Alcohol of 36° 50 cub. cents. +</pre> + +<p>The process is carried on exactly as if developing an ordinary +negative; but the action of the developer is stopped at the precise +moment when the positive has acquired intensity sufficient for the +purpose for which it is to be used. Fixing, varnishing, etc., are +then carried on the usual way. The great advantage of this process +consists in the fact of its rendering positives of much greater +delicacy than those that are taken by contact; and, on the other +hand, by means of it we are able to avoid two distinct operations, +when for certain kinds of work we require positive plates where a +negative would be of no service. M. V. Rau, the assistant who has +carried out this process under the direction of Captain Bing, has +described it in a work which has just been published by M. +Gauthier-Villars.</p> + +<p><i>Experiments of Captain Bing on the Sensitiveness of Coal +Oil</i>.--The same Captain of Engineers has undertaken a series of +very interesting experiments on the sensitiveness to light of one +or two substances to which bitumen probably owes its sensitiveness, +but which, contrary to what takes place with bitumen, are capable +of rendering very beautiful half tones, both on polished zinc and +on albumenized paper. These sensitive substances are extracted by +dissolving marine glue or coal-tar in benzine. By exposure to +light, both marine-glue and coal-tar turn of a sepia color, and, in +a printing-frame, they render a visible image, which is not the +case with bitumen; their solvents are in the order of their energy; +chloroform, ether, benzine, turpentine, petroleum spirit, and +alcohol. Of these solvents, benzine is the best adapted for +reducing the substances to a fluid state, so as to enable them to +flow over the zinc. The images obtained, which are permanent, and +which are very much like those of the Daguerreotype, are fixed by +means of the turpentine and petroleum spirit. They are washed with +water, and then carefully dried. It is possible to obtain prints +with half-tones in fatty ink by means of plates of zinc coated with +marine-glue. Some attempts in this direction were shown to me, +which promised very well in this respect. We are, therefore, in the +right road, not only for economically producing permanent prints on +paper, but also for making zinc plates in which the phototype film +of bichromatized gelatine is replaced by a solution of marine-glue +and benzine. The substance known in commerce under the name of +pitch or coal-tar will produce the same results.</p> + +<p><i>Bitumen Plates</i>.--A new method of making bitumen plates by +contact has also been introduced into the topographical studios. +The plan, or the original drawing, is placed against a glass plate, +coated with a mixture of bitumen and of marine-glue dissolved in +benzine. The marine-glue gives the bitumen greater pliancy, and +prevents it from scaling off when rubbed, particularly when the +plate is retouched with a dry point. These bitumen plates are so +thoroughly opaque to the penetration of the actinic rays, that the +printing-frame may be left for any time in full sunlight without +any fear of fog being produced on the zinc plate from which the +prints are to be taken.</p> + +<p><i>Method for Topographic Engraving by Commandant de la +Noë</i>.--Before leaving the interesting studios of which I +have been speaking, I ought to mention a very ingenious application +which has been made of a process called <i>topogravure</i>, +invented by Commandant de la Noë, who is the director of this +important department. A plate of polished zinc is coated with +bitumen in the usual way, and then exposed directly to the light +under an original drawing, or even under a printed plan. So soon as +the light has sufficiently acted, which may be seen by means of +photometric bands equally transparent at the plate, all the bitumen +not acted upon is dissolved. As it is a positive which has acted as +matrix, the uncovered zinc indicates the design, and the ground +remains coated with insoluble bitumen. The plate is then etched +with a weak solution of nitric acid in water, and the lines of the +design are thus slightly engraved; the surface is then re-coated +with another layer of bitumen, which fills up all the hollows, and +is then rubbed down with charcoal. All the surface is thus cleaned +off, and the only bitumen which remains is that in the lines, +which, though not deep, are sufficiently so to protect the +substance from the rubbing of the charcoal. When this is done we +have an engraved plate which can be printed from, like a +lithographic stone; it is gummed and wetted in the usual way, and +it gives prints of much greater delicacy and purity than those +taken directly from the bitumen. The ink is retained by the slight +projection of the surface beyond the line, so that it cannot +spread, and a kind of copper plate engraving is taken by +lithographic printing. Besides, in arriving at this result, there +is the advantage of being able to use directly the original plans +and drawings, without being obliged to have recourse to a plate +taken in the camera; the latter is indispensable for printing in +the usual way on bitumen where the impression on the sensitive film +is obtained by means of a negative. It will be seen that this +process is exceedingly ingenious, and not only is its application +very easy, but all its details are essentially practical.</p> + +<p><i>Succinate of Iron Developer</i>.--I have received a letter +from M. Borlinetto, in which he states that he has been induced by +the analogy which exists between oxalic and succinic acids to try +whether succinate of iron can be substituted for oxalate of iron as +a developer. To prove this he prepared some proto-succinate of iron +from the succinate of potassium and proto-sulphate of iron, +following the method given by Dr. Eder for the preparation of his +ferrous oxalate developer. He carried out the development in the +same way as is done by the oxalate, and he found that the succinate +of iron is even more energetic than the oxalate. The plate develops +regularly with much delicacy, and gives a peculiar tone. It is +necessary to take some fresh solution at every operation, on +account of the proto-succinate of iron being rapidly converted into +per-succinate by contact with the air.</p> + +<p><i>Method of Making Friable Hydro-Cellulose</i>.--At the meeting +of the Photographic Society of France, M. Girard showed his method +of preparing cellulose in a state of powder, specially adapted for +the production of pyroxyline for making collodion. Carded +cotton-wool is placed in water, acidulated with 3 per cent. of +sulphuric or nitric acid, and is left there from five to fifteen +seconds; it is then taken out and laid on a linen cloth, which is +then wrung so as to extract most of the liquid. In this condition +there still remains from 30 to 40 per cent. of acidulated water; +the cotton is divided into parcels and allowed to dry in the open +air until it feels dry to the touch, though in this condition it +still contains 20 per cent. of water. It is next inclosed in a +covered jar, which is heated to a temperature of 65° C.; the +desiccation therefore takes place in the closed space, and the +conversion of the material is completed in about two or three +hours. In this way a very perfect hydro-cellulose is obtained, and +in the best form for producing excellent pyroxyline.--<i>Corresp. +Photo Mews</i>.</p> + +<hr> +<p><a name="15"></a></p> + +<h2>PHOTO TRACINGS IN BLACK AND COLOR.</h2> + +<p>Two new processes for taking photo tracings in black and color +have recently been published--"Nigrography" and +"Anthrakotype"--both of which represent a real advance in +photographic art. By these two processes we are enabled for the +first time to accomplish the rapid production of positive copies in +black of plans and other line drawings. Each of these new methods +has its own sphere of action; both, therefore, should deserve +equally descriptive notices.</p> + +<p>For large plans, drawn with lines of even breadth, and showing +no gradated lines, or such as shade into gray, the process styled +"nigrography," invented by Itterbeim, of Vienna, and patented both +in Germany and Austria, will be found best adapted. The base of +this process is a solution of gum, with which large sheets of paper +can be more readily coated than with one of gelatine; it is, +therefore, very suitable for the preparation of tracings of the +largest size. The paper used must be the best drawing paper, +thoroughly sized, and on this the solution, consisting of 25 parts +of gum arabic dissolved in 100 parts of water, to which are added 7 +parts of potassium bichromate and I part of alcohol, is spread with +a broad, flat brush. It is then dried, and if placed in a cool, +dark place will keep good for a long time. When used, it is placed +under the plan to be reproduced, and exposed to diffused light for +from five to ten minutes--that is to say, to about 14° of +Vogel's photometer; it is then removed and placed for twenty +minutes in cold water, in order to wash out all the chromated gum +which has not been affected by light. By pressing between two +sheets of blotting-paper the water is then got rid of, and if the +exposure has been correctly judged the drawing will appear as dull +lines on a shiny ground. After the paper has been completely dried +it is ready for the black color. This consists of 5 parts of +shellac, 100 parts of alcohol, and 15 parts of finely-powdered +vine-black. A sponge is used to distribute the color over the +paper, and the latter is then laid in a 2 to 3 per cent. bath of +sulphuric acid, where it must remain until the black color can be +easily removed by means of a stiff brush. All the lines of the +drawing will then appear in black on a white ground. These +nigrographic tracings are very fine, but they only appear in +complete perfection when the original drawings are perfectly +opaque. Half-tone lines, or the marks of a red pencil on the +original, are not reproduced in the nigrographic copy.</p> + +<p>"Anthrakotype" is a kind of dusting-on process. It was invented +by Dr. Sobacchi, in the year 1879, and has been lately more fully +described by Captain Pizzighelli. This process--called also +"Photanthrakography"--is founded on the property of chromated +gelatine which has not been acted on by light to swell up in +lukewarm water, and to become tacky, so that in this condition it +can retain powdered color which had been dusted on it. Wherever, +however, the chromated gelatine has been acted on by light, the +surface becomes horny, undergoes no change in warm water, and loses +all sign of tackiness. In this process absolute opacity in the +lines of the original drawing is by no means necessary, for it +reproduces gray, half-tone lines just as well as it does black +ones. Pencil drawings can also be copied, and in this lies one +great advantage of the process over other photo-tracing methods, +for, to a certain extent, even half-tones can be produced.</p> + +<p>For the paper for anthrakotype an ordinary strong, well-sized +paper must be selected. This must be coated with a gelatine +solution (gelatine 1, water 30 parts), either by floating the paper +on the solution, or by flowing the solution over the paper. In the +latter case the paper is softened by soaking in water, is then +pressed on to a glass plate placed in a horizontal position, the +edges are turned up, and the gelatine solution is poured into the +trough thus formed. To sensitize the paper, it is dipped for a +couple of minutes in a solution of potassium bichromate (1 in 25), +then taken out and dried in the dark.</p> + +<p>The paper is now placed beneath the drawing in a copying-frame, +and exposed for several minutes to the light; it is afterward laid +in cold water in order to remove all excess of chromate. A copy of +the original drawing now exists in relief on the swollen gelatine, +and, in order to make this relief sticky, the paper is next dipped +for a short time in water, at a temperature of about 28° or +30° C. It is then laid on a smooth glass plate, superficially +dried by means of blotting-paper, and lamp-black or soot evenly +dusted on over the whole surface by means of a fine sieve. Although +lamp-black is so inexpensive and so easily obtained, as material it +answers the present purpose better than any other black coloring +substance. If now the color be evenly distributed with a broad +brush, the whole surface of the paper will appear to be thoroughly +black. In order to fix the color on the tacky parts of the +gelatine, the paper must next be dried by artificial heat--say, by +placing it near a stove--and this has the advantage of still +further increasing the stickiness of the gelatine in the parts +which have not been acted upon by light, so that the coloring +matter adheres even more firmly to the gelatine. When the paper is +thoroughly dry, place it in water, and let it be played on by a +strong jet; this removes all the color from the parts which have +been exposed to the light, and so develops the picture. By a little +gentle friction with a wet sponge, the development will be +materially promoted.</p> + +<p>A highly interesting peculiarity of this anthrakotype process is +the fact that a copy, though it may have been incorrectly exposed, +can still be saved. For instance, if the image does not seem to be +vigorous enough, it can be intensified in the simplest way; it is +only necessary to soak the paper afresh, then dust on more color, +etc.; in short, repeat the developing process as above described. +In difficult cases the dusting-on may be repeated five or six +times, till at last the desired intensity is obtained.</p> + +<p>By this process, therefore, we get a positive copy of a positive +original in black lines on a white ground. Of course, any other +coloring material in a state of powder may be used instead of soot, +and then a colored drawing on a white ground is obtained. Very +pretty variations of the process may be made by using gold or +silver paper, and dusting-on with different colors; or a picture +may be taken in gold bronze powder on a white ground. In this way +colored drawings may be taken on a gold or a silver ground, and +very bright photo tracings will be the result. Some examples of +this kind, that have been sent us from Vienna, are exceedingly +beautiful.</p> + +<p>Summing up the respective advantages of the two processes we +have above described, we may say that "nigrography" is best adapted +for copying drawings of a large size; the copies can with +difficulty be distinguished from good autographs, and they do not +possess the bad quality of gelatine papers--the tendency to roll up +and crack. Drawings, however, which have shadow or gradated lines +cannot be well produced by this process; in such cases it is better +to adopt "anthrakotype," with which good results will be +obtained.--<i>Photographic News</i>.</p> + +<hr> +<p><a name="17"></a></p> + +<h2>ON M. C. FAURE'S SECONDARY BATTERY.</h2> + +<p>The researches of M. Gaston Planté on the polarization of +voltameters led to his invention of the secondary cell, composed of +two strips of lead immersed in acidulated water. These cells +accumulate, and, so to speak, store up the electricity passed into +them from some outside generator. When the two electrodes are +connected with any source of electricity the surfaces of the two +strips of lead undergo certain modifications. Thus, the positive +pole retains oxygen and becomes covered with a thin coating of +peroxide of lead, while the negative pole becomes reduced to a +clean metallic state.</p> + +<p>Now, if the secondary cell is separated from the primary one, we +have a veritable voltaic battery, for the symmetry of the poles is +upset, and one is ready to give up oxygen and the other eager to +receive it. When the poles are connected, an intense electric +current is obtained, but it is of short duration. Such a cell, +having half a square meter of surface, can store up enough +electricity to keep a platinum wire 1 millim. in diameter and 8 +centims. long, red-hot for ten minutes. M. Planté has +succeeded in increasing the duration of the current by alternately +charging and discharging the cell, so as alternately to form layers +of reduced metal and peroxide of lead on the surface of the strip. +It was seen that this cell would afford an excellent means for the +conveyance of electricity from place to place, the great drawback, +however, being that the storing capacity was not sufficient as +compared with the weight and size of the cell. This difficulty has +now been overcome by M. Faure; the cell as he has improved it is +made in the following manner:</p> + +<p>The two strips of lead are separately covered with minium or +some other insoluble oxide of lead, then covered with an envelope +of felt, firmly attached by rivets of lead. These two electrodes +are then placed near each other in water acidulated with sulphuric +acid, as in the Planté cell. The cell is then attached to a +battery so as to allow a current of electricity to pass through it, +and the minium is thereby reduced to metallic spongy lead on the +negative pole, and oxidized to peroxide of lead on the positive +pole; when the cell is discharged the reduced lead becomes +oxidized, and the peroxide of lead is reduced until the cell +becomes inert.</p> + +<p>The improvement consists, as will be seen, in substituting for +strips of lead masses of spongy lead; for, in the Planté +cell, the action is restricted to the surface, while in Faure's +modification the action is almost unlimited. A battery composed of +Faure's cells, and weighing 150 lb., is capable of storing up a +quantity of electricity equivalent to one horsepower during one +hour, and calculations based on facts in thermal chemistry show +that this weight could be greatly decreased. A battery of 24 cells, +each weighing 14 lb., will keep a strip of platinum five-eighths of +an inch wide, one-thirty-second of an inch thick, and 9 ft. 10 in. +long, red-hot for a long time.</p> + +<p>The loss resulting from the charging and discharging of this +battery is not great; for example, if a certain quantity of energy +is expended in charging the cells, 80 per cent. of that energy can +be reproduced by the electricity resulting from the discharge of +the cells; moreover, the battery can be carried from one place to +another without injury. A battery was lately charged in Paris, then +taken to Brussels, where it was used the next day without +recharging. The cost is also said to be very low. A quantity of +electricity equal to one horse power during an hour can be +produced, stored, and delivered at any distance within 3 miles of +the works for 1½d. Therefore these batteries may become +useful in producing the electric light in private houses. A 1,250 +horsepower engine, working dynamo-machines giving a continuous +current, will in one hour produce 1,000 horse-power of effective +electricity, that is to say 80 per cent. of the initial force. The +cost of the machines, establishment, and construction will not be +more than £40,000, and the quantity of coal burnt will be 2 +lb. per hour per effective horse-power, which will cost (say) +½d. The apparatus necessary to store up the force of 1,000 +horses for twenty-four hours will cost £48,000, and will +weigh 1,500 tons. This price and these weights may become much less +after a time. The expense for wages and repairs will be less than +¼d. per hour per horse-power, which would be £24 a +day, or £8,800 a year; thus the total cost of one horse-power +for an hour stored up at the works is ¾d. Allowing that the +carriage will cost as much as the production and storing, we have +what is stated above, viz., that the total cost within 3 miles of +the works is 1½d. per horse-power per hour. This quantity of +electricity will produce a light, according to the amount of +division, equivalent to from 5 to 30 gas burners, which is much +cheaper than gas.--<i>Chemical News</i>.</p> + +<hr> +<p><a name="18"></a></p> + +<h2>PHYSICAL SCIENCE IN OUR COMMON SCHOOLS.</h2> + +<p>[Footnote: Read before the State Normal Institute at Winona, +Minnesota, April 28, 1881, by Clarence M. Boutelle, Professor of +Mathematics and Physical Science in the State Normal School.]</p> + +<p>Very little, perhaps, which is new can be said regarding the +teaching of physical science by the experimental method. Special +schools for scientific education, with large and costly +laboratories, are by no means few nor poorly attended; scientific +books and periodicals are widely read; scientific lectures are +popular. But, while in many schools of advanced grade, science is +taught in a scientific way, in many others the work is confined to +the mere study of books, and in only a few of our common district +schools is it taught at all.</p> + +<p>I shall advocate, and I believe with good reason, the use of +apparatus and experiments to supplement the knowledge gained from +books in schools where books are used, the giving of lessons to +younger children who do not use books, and the giving of these +lessons to some extent in all our schools. And the facts which I +have gathered together regarding the teaching of science will be +used with all these ends in view.</p> + +<p>Physics--using the term in its broadest sense--has been defined +as the science which has for its object the study of the material +world, the phenomena which it presents to us, the laws which govern +(or account for) these phenomena, and the applications which can be +made of either classes of related phenomena, or of laws, to the +wants of man. Thus broadly defined, physics would be one of two +great subjects covering the whole domain of knowledge. The entire +world of matter, as distinguished from the world of mind, would be +presented to us in a comprehensive study of physics.</p> + +<p>I shall consider in this discussion only a limited part of this +great subject. Phenomena modified by the action of the vital force, +either in plants or in animals, will be excluded; I shall not, +therefore, consider such subjects as botany or zoölogy. +Geology and related branches will also be omitted by restricting +our study to phenomena which take place in short, definite, +measurable periods of time. And lastly, those subjects in which, as +in astronomy, the phenomena take place beyond the control of +student and teacher, and in which their repetition at pleasure is +impossible, will not be considered. Natural philosophy, or physics, +as this term is generally used, and chemistry, will, therefore, be +the subjects which we will consider as sources from which to draw +matter for lessons for the children in our schools.</p> + +<p>The child's mind has the receptive side, the sensibility, the +most prominent. His senses are alert. He handles and examines +objects about him. He sees more, and he learns more from the +seeing, than he will in later years unless his perceptive powers +are definitely trained and observation made a habit. His judgment +and his will are weak. He reasons imperfectly. He chooses without +appropriate motives. He needs the building up and development given +by educational training. <i>Nature points out the method.</i></p> + +<p>Sensibility being the characteristic of his mind, we must appeal +to him through his senses. We must use the concrete; through it we +must act upon his weak will and immature judgment. From his natural +curiosity we must develop attention. His naturally strong +perceptive powers must be made yet stronger; they must be led in +proper directions and fixed upon appropriate objects. He must be +led to appreciate the relation between cause and effects--to +associate together related facts--and to state what he knows in a +definite, clear, and forcible manner.</p> + +<p>Object lessons, conversational lessons, lessons on animals, +lessons based on pictures and other devices, have been used to meet +this demand of the child's mental make up. Good in many respects, +and vastly better than mere book work, they have faults which I +shall point out in connection with the corresponding advantages of +easy lessons in the elements of science. I shall not quibble over +definitions. Object lessons may, perhaps, properly be said to +include lessons such as it seems to me should be given--lessons +drawn from natural philosophy or chemistry--but I use the term here +in the sense in which it is often used, as meaning lessons based +upon some object. A thimble, a knife, a watch, for instance, each +of these being a favorite with a certain class of object teachers, +may be taken.</p> + +<p>The objections are:</p> + +<p>1. Little new knowledge can be given which is simple and +appropriate. Most children already know the names of such objects +as are chosen, the names of the most prominent parts, the materials +of which they are composed and their uses. Much that is often given +should be omitted altogether if we fairly regard the economy of the +child's time and mental strength. It doesn't pay to teach children +that which isn't worth remembering, and which we don't care to have +them remember.</p> + +<p>2. Study of the qualities of materials is a prominent part of +lessons on objects. Such study is really the study of physical +science, but with objects such as are usually selected is a very +difficult part to give to young children. Ask the student who has +taken a course in chemistry whether the study of the qualities of +metals and their alloys is easy work. Ask him how much can readily +be shown, and how much must be taken on authority. Have him tell +you how much or how little the thing itself suggests, and how much +must he memorized from the mere book statement and with difficulty. +Study of materials is good to a certain extent, but it is often +carried much too far.</p> + +<p>Consider a conversational lesson on some animal. Lessons are +sometimes given on cats. As an element in a reading lesson--to +arouse interest--to hold the attention--to secure correct emphasis +and inflection--to make sure of the reading being good: such work +is appropriate. But let us see what the effect upon the pupil is as +regards the knowledge he gains of the cat, and the effect upon his +habits of thought and study. The student gives some statement as to +the appearance--the size--or some act of his cat. It is usually an +imperfect statement drawn from the imperfect memory of an imperfect +observation. And the teacher, having only a <i>general +knowledge</i> of the habits of cats, can correct in only a general +way. Thus habits of faulty and incorrect observation and inaccurate +memory are fastened upon the child. It is no less by the correction +of the false than by the presenting of the true, that we educate +properly.</p> + +<p>Besides this there is the fact that traits, habits, and +peculiarities of animals are not always manifested when we wish +them to be. Suppose a teacher asks a child to notice the way in +which a dog drinks, for example; the child may have to wait until +long after all the associated facts, the reasons why this thing was +to be observed--the lesson as a whole of which this formed a +part--have all grown dim in the memory, before the chance for the +observation occurs.</p> + +<p>Pictures are less valuable as educational aids than objects; at +best they are but partially and imperfectly concrete. The study of +pictures tends to cultivate the imagination and taste, but +observation and judgment are but little exercised.</p> + +<p>A comparison of the kind of knowledge gained in either of the +above ways with that gained by a study of science as such, will +make some of the advantages of the latter evident. An act of +complete knowledge consists in the identifying of an attribute with +a subject. Attributes of quality--of condition--of relation, may be +gained from lessons in which objects or pictures are used. +Attributes of action which are unregulated by the observer may be +learned from the study of animals. But very little of actions and +changes which can be made to take place under specified conditions, +and with uniformity of result, can be learned until physical +science is drawn upon.</p> + +<p>And yet consider the importance of such study. Changes around +him appeal most strongly to the child. "Why <i>does</i> this thing +<i>do</i> as it <i>does</i>?" is more frequent than "Why <i>is</i> +this thing as it <i>is</i>?" He sees changes of place, of form, of +size, of composition, taking place; his curiosity is aroused; and +he is ready to study with avidity, and in a systematic manner, the +changes which his teacher may present to him. Consider the +peculiarities belonging to the study of changes of any sort. The +interest is held, for the mind is constantly gaining the new. The +attention cannot be divided--all parts of the change, all phases of +the action, must be known, and to be known must be <i>observed</i>; +while in other forms of lessons the attention may be diverted for a +moment to return to the consideration of exactly what was being +observed before. It goes without saying that in one case quick and +accurate observation, a retentive memory, and the association of +causes and effects follow, and that in the other they do not.</p> + +<p>I advocate, therefore, the teaching of physical science in our +schools--<i>in all our schools</i>. Physical science taught by the +experimental method.</p> + +<p>An experiment has been defined as a question put to Nature, a +question asked in <i>things</i> rather than in <i>words</i>, and so +conditioned that no uncertain answer can be given. Nature says that +all matter gravitates, not in words, but in the swing of planets +around the sun, and in the leap of the avalanche. And men have +devised ingenious machines through which Nature may tell us the +invariable laws of gravitation, and give some hint as to why it is +true.</p> + +<p>There are two kinds of experiments, and two corresponding kinds +of investigators.</p> + +<p>I. In original investigation there are the following +elements:</p> + +<p>1. The careful determination of all the conditions under which +the experiment takes place.</p> + +<p>2. The observation of exactly what happens, with a painstaking +elimination of all previous notions as to what ought to happen.</p> + +<p>3. The change of conditions, one at a time, with a comparison of +the results obtained with the changes made, in order to determine +that each condition has been given just its appropriate weight in +the experiment.</p> + +<p>4. The classification and explanation of the result.</p> + +<p>5. The extension of the knowledge gained by turning it to +investigations suggested by what has already been learned.</p> + +<p>6. The practical application of the knowledge gained.</p> + +<p>II. In ordinary experiments for educational purposes the +experimenter follows in a general way in the footsteps of the +original investigator. There are the following elements to be +considered:</p> + +<p>1. The arrangement of conditions in general imitation of the +original investigator. This arrangement needs only to be general. +For example, if an original investigation were undertaken to +determine the composition of a metallic oxide, the metal and the +oxygen would both be carefully saved to be measured and weighed and +fully tested. The ordinary experiment would be considered +successful if oxygen and the metal were shown to result.</p> + +<p>2. The careful consideration of what should happen.</p> + +<p>3 The determination that the expected either does or does not +happen, with examination of reasons and elimination of disturbing +causes in the latter case.</p> + +<p>4. The accepting as true of the classification and explanation +already given. Theories, explanations, and laws are thus accepted +every day by minds which could never have originated either them or +the experiments from which they were derived.</p> + +<p>The method of original investigation, strictly considered, +presents many difficulties. A long course of preliminary +training--a thorough knowledge of what has been done in a given +field already--a quick imagination--a genius for devising forms of +apparatus which will enable him to work well under particular +conditions in the most simple and effective way--the faculty of +suspending judgment, and of seeing what happens, all that happens, +and just how it happens--patience--caution--courage--quick judgment +when a completed experiment presses for an explanation--these are +some of the characteristics which must belong to the original +worker.</p> + +<p>Were we all capable of doing such work there would be these +advantages, among others, of studying for ourselves:</p> + +<p>1. What we find out for ourselves we remember longer and recall +more readily than what we acquire in any other way. This advantage +holds true whether the facts learned are entirely new or only new +to us. Almost every man whose life has been spent in study has a +store of facts which he discovered, and on which he built hopes of +future greatness until he found out later that they were old to the +knowledge of the world he lived in. And these things are among +those which will remain longest in his memory.</p> + +<p>2. Associated facts would be learned in studying in this way +which would remain unknown otherwise.</p> + +<p>But all the advantages would be associated with disadvantages +too. Long periods of time would have to be given for comparatively +small results. The history of science is full of instances in which +years were spent in the elaboration of some law, or principle, or +theory which the school boy of to-day learns in an hour and recites +in a breath. Why does water rise in a pump? Do all bodies, large +and small, fall equally fast? The principles which answer and +explain such questions can be made so clear and evident to the mind +of a pupil that he would almost fancy they must have been known +from the first instead of having waited for the hard, earnest labor +of intellectual giants. And science has gone on, and for us and for +our pupils would still go on, only as accompanied with numerous +mistakes and disappointments.</p> + +<p>What method shall we adopt in the teaching of science? It must +differ according to the age and capacity of the pupils. An +excellent modification of the method of original investigation may +be arranged as follows:</p> + +<p>The children are put in possession of all facts relating to +conditions, the teacher explaining them as much as may be +necessary. The experiment is performed, the pupils being required +to observe exactly what takes place, the experiments selected being +of such a nature that any previous judgment as to what ought to +occur is as nearly impossible as may be. We predict from knowledge, +real or supposed, of facts which are associated in our minds with +any new subject under consideration. Children often know in a +general, vague, and indefinite way that which, for the sake of a +full and systematic knowledge, we may desire them to study. What +they know will unconsciously modify their expectations, and their +expectations in turn may modify their observations. We are apt to +believe that happens which we expect will happen. There ought to be +no difficulty, however, in finding simple and appropriate +experiments with which the child is entirely unacquainted, and in +which anything beyond the wildest guess work is, for him, +impossible. The principal use which can be made of this method is +in the mere observation of what takes place. Nothing which the +child notices correctly need be rejected, no matter how far removed +from the chief event on the object of the experiment. Care that the +pupil shall see all, and separate the essential from the +accidental, is all that is necessary.</p> + +<p>But the original investigator assigns reasons, and with care the +children may be allowed to attempt that. This, however, should not +be carried far; incorrect explanations should be criticised; and +the class should at length be given all the elements of the correct +explanation which they have not determined for themselves. Later, +pupils should be encouraged to name related phenomena, to mention +things which they have seen happen which are due to associated +causes, and to suggest variations for the experiment and tests for +its explanation. Good results may be made to follow this kind of +work even with very young pupils. A child grows in mental strength +by using the powers he has, and mistakes seen to be such are not +only steps toward a correct view of the subject under +consideration, but are steps toward that habit of mind which +spontaneously presents correct views at once in study which comes +later in life.</p> + +<p>Another method is this: The pupil may know what is expected to +happen, as well as the conditions given, and held responsible for +an observation of what does happen and a comparison of what he +really observes with what he expects to observe. Explanations are +usually given a class, often in books with which they are +furnished, instead of being drawn from them, in whole or in part, +by questioning, when physical science is studied in this way. +Indeed, this method is a necessity when text books are used, unless +experiments from some outside source are introduced.</p> + +<p>Who shall perform the experiments? With young pupils everywhere, +and in most of our common, and even in many of our graded schools, +the experiments must be performed by the teacher. With young pupils +the time is too limited, and the responsibility and necessary care +too great to permit of any other plan being practical. In many of +our schools the small supply of apparatus renders this necessary +even with larger pupils. Added to the reasons already given is the +important one that in no other way--by no other plan--can the +teacher be as readily sure that his pupils observe and reason fully +for themselves. In this normal school a course in physics, in which +the experiments are all performed in the class room by the teacher, +is followed by a course in chemistry, in which the members of the +class perform the experiments for themselves in the laboratory. +And, notwithstanding the age, maturity, and previous observation of +the pupils, a great deal must be done both in the laboratory and in +the recitation room to be sure that all that happens is seen--that +the purpose is clearly held in the mind--that the reason is fully +understood.</p> + +<p>With older pupils and greater facilities, however, the +experiments should be performed by the pupils themselves. Constant +watchfulness is necessary, it is true, to insure to the pupil the +full educational value of the experiment. With this watchfulness it +can be done, and the advantages are numerous. Among them are:</p> + +<p>1. The learning of the use and care of apparatus.</p> + +<p>2. The learning of methods of actual construction, from +materials at hand, of some of the simpler kinds of apparatus.</p> + +<p>3. The learning of the importance of careful preparation. An +experiment may be performed in a few minutes before a class which +has taken an hour or more of time in its preparation. The pupil +fully appreciates its importance, and is in the best condition to +remember it only when he has had a part of the hard work attending +that preparation. Again, conditions under which an experiment is +successfully performed are often not appreciated when merely stated +in words. "To prepare hydrogen gas, pass a thistle tube and a +delivery tube through a cork which fit tightly in the neck of a +bottle," etc., is simple enough. Let a pupil try with a cork which +does not fit tightly and he will never forget that condition.</p> + +<p>4. The learning of the importance of following directions. +Chemistry, especially, is full of those cases where this means +everything. Sometimes, not often in experiments performed in +school, however, it may mean even life or death.</p> + +<p>The time for experiments should be carefully considered. When +performed by the teacher they should be taken up during the +recitation:</p> + +<p>1. If used as a foundation to build upon, at the beginning of +the lesson.</p> + +<p>2. If used as a summary, at the close.</p> + +<p>3. They should be closely connected with the points which they +illustrate.</p> + +<p>4. When very short, or when so difficult as to demand the whole +attention of the teacher, they may be given and afterward +discussed. If long or easy, they may be discussed while the work is +going on. Changes which take place slowly, as those which are +brought about by the gradual action of heat, for instance, are best +taken up in this latter way.</p> + +<p>5. Exceptions may be necessary, as when experiments which demand +special preparation immediately before they are presented are given +when the recitation begins, or cases in which experiments are kept +until near the close of a recitation, when the teacher finds that +attention flags and the lesson seems to have lost its interest to +the pupils as soon as the experiments have been given.</p> + +<p>When performed by the pupils themselves, experiments should come +before the recitation as a part of the preparation for the work of +the class room.</p> + +<p>Even in those cases in which the teacher performs the work, +opportunity should be given, from time to time, for the performing +of the experiment by the pupils themselves. This can be done in +several ways. During the course in physics here I am in the habit +of leaving apparatus on the table in my room for at least one day, +often for a longer time, and of giving permission to my class to +perform the experiments for themselves when their time permits and +the nature of the experiment makes it an advantage to get a nearer +view than was possible in the class work. I leave it to them to +decide when to perform the experiments, or whether it is to their +advantage to take the time to perform them at all. I make no +attempt to watch either pupils or apparatus, although I would often +assist or explain at intermissions or during the afternoon. The +apparatus was largely used, and the effect on recitations was a +good one. For advanced pupils, and those who can be fully trusted, +the plan is a good one. The only question is the safety of the +apparatus; each teacher can decide for himself regarding the +advisability of the plan for his own school.</p> + +<p>With smaller pupils their own safety may render it best to keep +apparatus out of their hands, except under the immediate direction +of the teacher. With all pupils that is, doubtless, the best plan +where chemicals are concerned.</p> + +<p>Another method is to allow pupils to assist the teacher in the +preparation of experiments, to call occasionally upon members of +the class to come forward and give the experiment in the place of +the teacher, and to encourage home work relating to experiments. +This latter is often spontaneous on the part of older pupils, and +can be brought about with the smaller ones by the use of a little +tact; many of the toys of the present day have some scientific +principle at bottom; let the teacher find out what toys his young +pupils have, and encourage them to use them in a scientific +way.</p> + +<p>In whatever ways experiments be used, the class should be made +to consider the following elements as important in every case:</p> + +<p>1. The purpose of the experiment. The same experiment may be +performed at one time for one purpose, at another time for another. +The purpose intended should be made the prominent thing, all others +being subordinated to it. Many chemical reactions, for instance, +can be made to yield either one of two or more substances for study +or examination, or use, while it may be the purpose of the +experiment to close only one of them.</p> + +<p>2 The apparatus. All elements should be considered. The +necessary should be separated from that which may vary. In cases +where the various parts must have some definite relation to the +others as regards size or position, all that should be considered +with care. In complex apparatus the exact office of each part +should be understood.</p> + +<p>3. A clear understanding of what happens. To this I have already +referred.</p> + +<p>4. Why it happens.</p> + +<p>5. In what other way it might be made to happen. In chemistry +almost every substance can be prepared in several different ways. +The common method is in most cases made so by some consideration of +convenience, cheapness, or safety. Often only one method is +considered in one place in a text book. In a review, however, +several methods can be associated together. Tests, uses, etc., will +vary, too, and should be studied with that fact in view. In physics +phenomena illustrating a given principle can usually be made to +take place in several different ways. Often very simple apparatus +will do to illustrate some fact for which complex and costly +apparatus would be convenient. In such case the study of the +experiment with that fact in view becomes important to us who need +to simplify apparatus as much as possible.</p> + +<p>6. Special precautions which may be necessary. Some experiments +always work well, even in the hands of those not used to the work. +Others are successful--sometimes safe, even--only when the greatest +care is taken. Substances are used constantly in work in chemistry +which are deadly poisons, others which are gaseous and will pass +through the smallest holes. In physics the experiments usually +present fewer difficulties of this sort. But special care is +necessary to complete success here.</p> + +<p>7. Other things shown by the experiment. While the main object +should be kept in most prominent view in all experimental work, the +fullest educational value will come only when all that can be +learned by the use of an experiment is carefully considered.</p> + +<p>In selecting just the work to be taken up with a given class of +children, attention must be paid to the selection of the +appropriate matter to be presented and the well adapted method of +presenting it. The following points should be carefully +considered:</p> + +<p>1. The matter must be adapted to the capacity of the child. This +must be true both as regards the quality and the quantity. The +tendency will be to teach too much when the matter presented is +entirely new, but too little in many cases where the pupil already +knows the subject in a general way. Matter is valuable only when +given slowly enough to permit of its being fully understood and +memorized, while on the other hand method is valuable only when it +secures the development of attention and the various faculties of +the child's mind by presenting a sufficient amount of the new.</p> + +<p>2. The work must be based on what is already known. This, one of +the best known of the principles of teaching, is of at least as +great importance in physical science as in any other department of +knowledge. It seems to me in many cases to be more important here +than elsewhere. It is not necessary to reach each point by passing +over every other point usually considered. Lessons in electricity +or sound, for instance, can be given to children who have done +nothing with other parts of science. But a natural beginning must +be made, and an orderly sequence of lessons adopted. Children will +not do what adults would find almost impossible in covering gaps +between lessons.</p> + +<p>Science may be compared to a great temple. Pillars, each built +of many curiously joined stones, standing at the very entrance, +represent the departments of science so far as man has studied +them. We need not dig down and study the foundations with the +children; we need not study every pillar nor choose any particular +one rather than some other; but we must learn something of every +stone--of each great fact--in the pillar we select, be it ever so +little. The original investigator climbs to stones never before +reached, or boldly ventures away into the dim recesses beyond the +entrance to bring back hints of what may be known and believed a +hundred years hence, perhaps. The exact investigator measures each +stone. Patiently and toilsomely scientific men examine them with +glass and reagent. We need not do this, but we must omit none of +the stones.</p> + +<p>3. The work must be continuous. To continue the figure, the +stones must be considered in some regular order. One lesson in +electricity, one in sound, then one in some other department is +injurious. We remember best by associated facts, and, while with +the child this is less so than with the man, one great object of +this work is to teach him to remember in that way.</p> + +<p>4. Experiments should never be performed for mere show. Of two +experiments which illustrate a fact equally well it is often best +to select the most striking and brilliant one. The attention and +interest of the child will be gained in this way when they would +not be to so great an extent in any other. The point of the +experiment, however, should never be lost sight of in attention to +the merely wonderful in it.</p> + +<p>With older pupils, and especially with those who use books for +themselves and perform the experiments there considered, the fact +that experiments demand work, downright hard work, with care, and +patience, and perseverance, and courage, cannot be kept too +prominently before them.</p> + +<p>5. Every lesson should have a definite object. Not the general +value of the experiment, but some <i>one thing</i> which it shows +should be the object considered.</p> + +<p>6. Each experiment should be associated with some truth +expressed in words. The experiment should be remembered in +connection with a definite statement in each case. The memory of +either the experiment, or the principle apart from the experiment, +is a species of half knowledge which should be avoided. An +unillustrated principle must, when the necessity arises, be stored +in the memory; and in the systematic study of books this necessity +will often come. But we should never crowd this abstract work on +the memory unassisted by the suggestive concrete, when the concrete +aid is possible.</p> + +<p>7. All that is taught should be true. It is not necessary to +attempt to exhaust a subject, nor to attempt to teach minute +details regarding it to the pupils in our schools, but it is +necessary that every statement given to the pupil to be learned and +remembered should contain no element of falsehood.</p> + +<p>The student in mathematics experiences a feeling of growing +strength and power when he finds, in algebra, that the formula he +used in arithmetic in extracting a square root has grown in +importance by leading indirectly to a theorem of which it is only +one particular case--a theorem with a more definite proof, and a +larger capability for use than he had thought possible. When he +finds a still simpler proof for the binomial theorem in his study +of the calculus, his feeling of increasing power and the desire for +still greater results deepens and intensifies. Were he to find, on +the contrary, that from a false notion of the means to be used in +making a thing simple, his teacher in arithmetic had taught him +what is false, we should approve his feeling of disgust and +disappointment. Early impressions are the most lasting, and the +hardest part of school work for the teacher is the unteaching of +false ideas, and the correcting of imperfectly formed and partially +understood ideas. I took a case from mathematics, the exact +science, to illustrate this point. But I must not neglect to notice +the difference between that subject and physical science. The +latter consists of theories, hypotheses, and so-called laws, +supported by <i>observed facts</i>. The facts remain, but time has +overthrown many of the hypotheses and theories, and it will +doubtless overthrow more and give us something better and truer in +their place. While a careful distinction between what is known and +what is believed is necessary, I should always class the teaching +of accepted theories and hypotheses with the teaching of the +true.</p> + +<p>But teachers, with more of imagination than good sense, teach +distinctions which do not exist, generalizations which do not +generalize, and do incalculable mischief by so doing.</p> + +<p>8. Experimental work should be thoroughly honest as to +conditions and results. If an experiment is not the success you +expected it would be, say so honestly, and if you know why, explain +it. The pupil should be taught to know just what <i>is</i>, theory +or expectation to the contrary notwithstanding. Discoveries in +physical science have often originated in a search for the reason +for some unexpected thing.</p> + +<p>The relation of the study of science to books on science should +be considered. For the work done with pupils before they are given +books to use for themselves, any attempt to follow a text book is +to be deplored. The study of the properties of matter, for +instance, would be a fearful and wonderful thing to set a class of +little ones at as a beginning in scientific work. Just what matter, +and force, and molecules, and atoms are may be well enough for the +student who is old enough to begin to use a book, but they would be +but dry husks to a younger child. Many of the careful +classifications and analyses of topics in text books had far better +be used as summaries than in any other way; and a definition is +better when the pupil knows it is true than when he is about to +find out whether it is or not.</p> + +<p>An ideal course in science would be one in which nothing should +be learned but that found out by the observation of the pupil +himself under the guidance of the teacher, necessary terms being +given, but only when the thing to be named had been considered, and +the mind demanded the term because of a felt need. Practically such +a method is impossible in its fullest sense, but a closer approach +to it will be an advantage.</p> + +<p>Among the numerous good results which will follow the study of +physical science are the following:</p> + +<p>1. The cultivation of all the faculties of the child in a +natural order, thus making him grow into a ready, quick, and +observing man. Education in schools is too often shaped so as to +repress instead of cultivate the instinctive desire for the +<i>knowledge of things</i> which is found in every child.</p> + +<p>2. The mechanical skill which comes from the preparation and use +of apparatus.</p> + +<p>3. The ability to follow directions.</p> + +<p>4. The belief in stated scientific facts, the understanding of +descriptions, diagrams, etc.</p> + +<p>5. The habitual scientific use of events which happen around +us.</p> + +<p>6. The study of the old to find the new. The principle of the +telephone, for instance, is as old as spoken language. The mere[1] +pulses in the air--carrying all the characteristics of what you +say--may set in vibration either the drum of my ear, or a disk of +metal. How simple--and how simple all true science is--when we +understand it.</p> + +<p>[Transcribers note 1: corrected from 'more']</p> + +<p>8. The cultivation of the scientific judgment, and the inventive +powers of the mind. One great original investigator, made such by +the direction given his mind in one of our common schools, would be +cheaply bought at the price of all that the study of science in our +schools will cost for the next quarter of a century.</p> + +<p>8. Honesty. If there is a study whose every tendency is more in +the direction of honesty and truthfulness--both with ourselves and +with others--than is the study of experimental science, I do not +know what it is.</p> + +<p>Physical science, then, will help in making men and women out of +our boys and girls. It is worthy of a fair, earnest trial +everywhere.</p> + +<p>A few minutes each day in which a class or a school study +science in some of the ways I have indicated will give a knowledge +at the end of a term or a year of no mean value. The time thus +spent will have rested the pupils from their books, to which they +will return refreshed, and instead of being time lost from other +study the work will have been made enough more earnest and intense +to make it again.</p> + +<p>Apparatus for illustrating many of the ordinary facts of physics +can be devised from materials always at hand. Many more can be made +by any one skilled in the use of tools. In chemistry, the +simplicity of the apparatus, and comparative cheapness of ordinary +chemicals, make the use of a large number of beautiful and +instructive experiments both easy and cheap.</p> + +<p>A nation is what its trades and manufactures--its inventions and +discoveries--make it; and these depend on its trained scientific +men. Boys become men. Their growing minds are waiting for what I +urge you to offer. Science has never advanced without carrying +practical civilization with it--but it has never truly advanced +save by the use of the experimental method. <i>And it never +will</i>.</p> + +<p>Let us then look forward to the time when our boys and young +men--our girls and young women--shall extend the boundaries of +human knowledge by its use, fitted so to do by what we may have +done for them.</p> + +<hr> +<p><a name="21"></a></p> + +<h2>GEOGRAPHICAL SOCIETY OF THE PACIFIC.</h2> + +<p>This society is a recent organization, the objects of which are +to encourage geographical exploration and discovery; to investigate +and disseminate geographical information by discussion, lectures, +and publications; to establish in this, the chief maritime city of +the Western States, for the benefit of commerce, navigation, and +the industrial and material interests of the Pacific slope, a place +where the means will be afforded of obtaining accurate information +not only of the countries bordering on the Pacific ocean, but of +every part of the habitable globe; to accumulate a library of the +best books on geography, history, and statistics; to make a +collection of the most recent maps and charts--especially those +which relate to the Pacific coast, the islands of the Pacific and +the Pacific ocean--and to enter into correspondence with scientific +and learned societies whose objects include or sympathize with +geography.</p> + +<p>The society will publish a bulletin and an annual journal, which +will interchange with geographical and other societies. Monthly +meetings are to be held, at which original papers will be read or +lectures be given; and to which, as well as to the entertainments +to distinguished travelers, to the conversazioni, and to the +informal evenings, the fellows of the society will have the +privilege of introducing their friends. The initiation fee to the +society is $10; monthly dues $1; life fellowship $100.</p> + +<p>At a meeting held at the Palace Hotel on the 12th May, the +following gentlemen were elected for the ensuing year: President, +Geo. Davidson; Vice-Presidents, Hon. Ogden Hoffman, Wm. Lane +Booker, H.B.M. Consul, and John R. Jarboe; Foreign Corresponding +Sec., Francis Berton; Home Cor. Sec., James P. Cox; Treas., Gen. C. +I. Hutchinson; Sec'y, C. Mitchell Grant, F.R.G.S. The council is +composed of the following: Hon. Joseph W. Winans, Hon. J.F. +Sullivan, Ralph C. Harrison, A.S. Hallidie, Thos. E. Stevin, +F.A.G.S., W.W. Crane, Jr., W.J. Shaw, C.P. Murphy, Thos. Brice, +Edward L.G. Steele, Gerrit L. Lansing, Joseph D. Redding. The +Trustees are Geo. Davidson, Wm. Lane Booker, Hon. Jno. S. Hager, +Geo. Chismore, M.D., Selim Franklin.</p> + +<hr> +<p><a name="22"></a></p> + +<h2>THE BEHRING'S STRAITS CURRENTS.</h2> + +<p>It will be remembered that a short time since we mentioned the +fact that W.H. Dall, of the U. S. Coast Survey, who has passed a +number of years in Alaskan waters, on Coast Survey duty, denied the +existence of any branch of the Kuro Shiwo, or Japanese warm stream, +in Behring's Straits. That is, he failed to find evidence of the +existence of any such current, although he had made careful +observations. At the islands in Behring's Straits, his vessel had +sailed in opposite directions with ebb and flood tide, and he +thought the only currents there were tidal in their nature. The +existence or non-existence of this current is an important point in +Arctic research on this side of the continent.</p> + +<p>At the last meeting of the Academy of Sciences, Prof. Davidson, +of the U. S. Coast Survey, author of the "Alaska Coast Pilot," +refuted Dr. Dall's opinion of the non-existence of a branch of the +Kuro Shiwo, or Japanese warm stream, from the north Pacific into +the Arctic Ocean, through Behring's Straits. He said that in 1857 +he gave to the Academy his own observations, and recently he had +conferred with Capt. C.L. Hooper, who commanded the U. S. steamer +Thomas Corwin, employed as a revenue steam cruiser in the Arctic +and around the coast of Alaska. Capt. Hooper confirms the opinions +of all previous navigators, every one of which, except Dr. Dall, +say that a branch of this warm stream passed northward into the +Arctic through Behring's Strait. It is partly deflected by St. +Lawrence Island, and closely follows the coast on the Alaskan side, +while a cold current comes out south, past East Cape in Siberia, +skirting the Asiatic shore past Kamschatka, and thence continues +down the coast of China. He said ice often extended several miles +seaward, from East Cape on the Asiatic side of Behring Strait, +making what seamen call a false cape, and indicating cold water, +while no such formation makes off on the American side, where the +water is 12 degrees warmer than on the Asiatic shore off the +Diomede islands, situated in the middle of Behring's Strait, the +current varies in intensity according to the wind.</p> + +<p>Frequently it is almost nothing for several days, when after a +series of southerly winds the shallow Arctic basin has been filled, +under a heavy pressure, with an unusual volume of water, and a +sudden change to northerly winds, makes even a small current +setting southward for a few days, just as at times the surface +currents set out our Golden Gate continuously for 24 and 48 hours, +as shown by the United States Coast Survey tide gauges. Whalers +report that the incoming water then flows in, under the temporary +outflowing stream.</p> + +<p>Old trees, of a variety known to grow in tropical Japan, are +floated into the Arctic basin as far as past Point Barrow, on the +American side, but none are found on the Asiatic side, or near +Wrangell Land, where a cold stream exists, and ice remains late in +the season. On the northern side of the Aleutian islands are found +cocoanut husks and other tropical productions stranded along the +beaches. The American coast of Alaska has a much warmer climate +than the Asiatic coast of Siberia, and the American timber line +extends very far north. The ice opens early in the season on the +American side, and invariably late on the Asiatic.</p> + +<p>Capt. C. L. Hooper says that when just north of Behring's +Strait, off the American coast, in the Arctic basin, the U.S. +steamer Thomas Corwin, when becalmed for 24 hours, drifted 40 miles +to the northward. From all these, and other facts, and the +unanimous testimony of American whalemen, who have for years spent +many months annually in the Arctic, and from his own observations, +he argued that a branch of the Kuro-Shiwo or Japanese warm stream, +unquestionably runs northward through Behring's Strait into the +Arctic basin along the northwestern coast of Alaska.</p> + +<p>Prof. Davidson then called to mind the testimony in regard to +the existence of Plover Island, between Herald Island and Wrangell +Land, which he said was first made public through this academy. The +evidence of Capts. Williams and Thomas Long were recited and highly +praised. One of the officers of Admiral Rodgers' expedition climbed +to near the top of Herald Island, at a time of great refraction, +when probably a false horizon existed, and hence did not see Plover +Island, although Wrangell Land was in sight.</p> + +<p>Prof. Davidson thinks all the authorities are against Dr. Dall, +who attributes the warm current he observed on the American coast +to water from the Yukon River and to the large expanse of shallow +water exposed to the sun's rays. As Dall's observations only +covered a few days of possibly exceptional weather, and the whalers +and Captain Hooper's cover vastly longer periods, and whalers all +say it is a pretty hard thing to beat southward through Behring's +Strait, owing to the northerly current setting into the Arctic, we +are forced to the conclusion that Dr. Dall has mistaken the +exception for the rule, and his conclusions are therefore +erroneous. When, in 1824, Wrangell went north, he, like others, +always found broken ice and considerable open water. In 1867, when +Capt. Thomas Long made his memorable survey of the coast of +Wrangell Land, the season was an exceptionally open one, and in +California we had heavy rains, extending into July.</p> + +<hr> +<p><a name="23"></a></p> + +<h2>EXPERIMENTAL GEOLOGY.</h2> + +<h3>ARTIFICIAL PRODUCTION OF CALCAREOUS PISOLITES AND OOLITES.</h3> + +<p>Mr. Stanislas Meunier communicates to <i>Le Nature</i> an +account of some interesting specimens of globular calcareous +matter, resembling pisolites or peastones both in appearance and +structure, which were accidentally formed as follows: The Northern +Railway Company, France, desiring to purify some calciferous water +designed for use in steam boilers, hit upon the ingenious expedient +of treating it with lime water whose concentration was calculated +exactly from the amount of lime held in the liquid to be purified. +The liquids were mixed in a vast reservoir, to which they were led +by parallel pipes, and by which they were given a rapid eddying +motion. The transformation of the bicarbonate into neutral +carbonate of lime being thus effected with the accompaniment of a +circling motion, the insoluble salt which precipitated, instead of +being deposited in an amorphous state, hardened into globules, the +sizes of which were strictly regulated by the velocity of the +currents. Those that have been formed at one and the same operation +are uniform, but those formed at different times vary +greatly--their diameters varying by at least one millimeter to one +and a half centimeters. The surface of the smaller globules is +smooth, but that of the larger ones is rough. Even by the naked +eye, it may be seen that both the large and small globules are +formed of regularly superposed concentric layers. If an extremely +thin section be made through one of them it is found that the +number of layers is very great and that they are remarkably regular +(A). By the microscope, it has been ascertained that each layer is +about 0.007 of a millimeter in thickness.</p> + +<p>On observing it under polarized light the calcareous substance +is discovered to be everywhere crystallized, and this suggests the +question whether the carbonate has here taken the form of aragonite +or of calcite. Examination has shown it to be the latter. The +density of the globules (2.58) is similar to that of ordinary +varieties of calcite. It is probable that if the operation were to +take place under the influence of heat, under the conditions above +mentioned, aragonite would be formed. It is hardly necessary to +dwell upon the possible geological applications of this mode of +forming calcareous oolites and pisolites.</p> + +<h3>ON CRYSTALS OF ANHYDROUS LIME.</h3> + +<p>Some time ago it was discovered that some limestone, which had +been submitted for eighteen months to a heat of nearly 1,000 +degrees in the smelting furnaces of Leroy-Descloges (France), had +given rise to perfectly crystallized anhydrous lime. Figure C shows +three of these crystals magnified 300 diameters. It will be noticed +that they have a striking analogy with grains of common salt. They +are, in fact, cubes (often imperfect), but do not polarize light, +as a substance of the first crystalline system should. However, it +is rarely the case that the crystals do not have <i>some</i> action +on light. Most usually, when the two Nicol prisms are crossed so as +to cause extinction, the crystals present the appearance shown at +D. That is to say, while the central portion is totally inactive +there are seen on the margins zones which greatly brighten the +light.</p> + +<p class="ctr"><img src="images/10a.png" alt=""></p> + +<p>A and B.--Calcareous Pisolites and Oolites produced +artificially. A.--External aspect and section of a Pisolite. +B.--Details of internal structure as seen by the microscope.</p> + +<p>C and D.--Crystals of anhydrous Lime obtained artificially. +C.--Crystals seen under the microscope in the natural light. +D.--Crystals seen under the microscope in polarized light.</p> + +<p>The phenomenon is explained by the slow carbonization of the +anhydrous lime under the influence of the air; the external layers +passing to the state of carbonate of lime or Iceland spar, which, +as well known, has great influence on polarized light. This +transformation, which takes place without disturbing the +crystalline state, does not lead to any general modification of the +form of the crystals, and the final product of carbonization is a +cubic form known in mineralogical language as <i>epigene</i>. As +the molecule of spar is entirely different in form from the +molecule of lime, the form of the crystal is not absolutely +preserved, and there are observed on the edges of the epigene +crystal certain grooves which correspond with a loss of substance. +These grooves are quite visible, for example, on the crystal to the +left in Fig. D.</p> + +<p>Up to the present time anhydrous lime has been known only in an +amorphous state. The experiment which has produced it in the form +noted above would doubtless give rise to crystallized states of +other earthy oxides likewise, and even of alkalino-earthy +oxides.</p> + +<p><a name="24"></a></p> + +<h2>COCCIDÆ.</h2> + +<p>[Footnote: A paper recently read before the California Academy +of Sciences.]</p> + +<h3>By DR. H. BEHR.</h3> + +<p>With the exception of Hymenoptera there is no group of insects +that interfere in so many ways in good and evil with our own +interests, as that group of Homoptera called Coccidæ.</p> + +<p>But while the Hymenoptera command our respect by an intellect +that approaches the human, the Coccus tribe possesses only the +lowest kind of instinct, and its females even pass the greater part +of their lives in a mere vegetation state, without the power of +locomotion or perception, like a plant, exhibiting only organs of +assimilation and reproduction.</p> + +<p>But strange to say, these two groups, otherwise so very +dissimilar, exhibit again a resemblance in their product. Both +produce honey and wax.</p> + +<p>It is true, the honey of this tribe is almost exclusively used +by the ants. But I have tasted the honey-like secretion of an +Australian lecanium living; on the leaves of Eucalyptus dumosus; +and the manna mentioned in Scripture is considered the secretion of +Coccus manniparus (Ehrenberg) that feeds on a tamarix, and whose +product is still used by the native tribes round Mount Sinai.</p> + +<p>Several species of Coccides are used for the production of wax; +many more, among which the Cochenill, for dyes.</p> + +<p>All these substances can be obtained in other ways, even the +Cochenill is to a great extent superseded by aniline dyes, but in +regard to one production, indispensable to a great extent, we are +entirely dependent on some insects of this family; it is the +Shellac, lately also found in the desert regions around the Gila +and Colorado on the Larrea Mexicana. You will remember that +excellent treatise on this variety of Shellac, written by Professor +J.M. Stillman at Berkeley, on its chemical peculiarities.</p> + +<p>But all these different forms of utility fall very lightly in +weight, and can not even be counted as an extenuating circumstance, +when we compare them to the enormous evils brought on farmer and +gardener by the hosts of those Coccides that visit plantations, +hothouses, and orchards.</p> + +<p>To combat successfully against these insect-pests we have first +to study their habits and then adapt to them our remedies, which +you will see are more effective when well administered than those +which we possess against insect pests of other classes.</p> + +<p>I give here only the outlines of their natural history, +peculiarities that are common to all, for it would be impossible to +go into detail. Where there are exceptions of practical importance +I will mention them.</p> + +<p>In countries with a well defined winter the winged males appear +as soon as white frosts are no more usual, and copulate with the +unwieldy limbless female, that looks more like a gall or morbid +excrescence, than a living animal. Shortly after the young ones are +perceptible near the withered body of their mother, covered by waxy +secretions that look somewhat like a feathery down.</p> + +<p>These young ones are lively enough, they move about with +agility, and it is not till high summer that they fasten themselves +permanently, and lose feet and antennae, organs of locomotion and +perception that are no more of any use to them. (There is a slight +difference in this regard between different genera, as for +instance, Coccus and Dorthesia retain these organs in different +degrees of imperfection, Lecanium and Aspidiotus losing every trace +of them.)</p> + +<p>In this limbless, senseless state the females remain fall and +winter. Toward the end of winter these animated galls begin to +swell, and those containing males enter the state of the chrysalis, +from which the males emerge at the beginning of the warm season and +fecundate the gall-like females, which undergo neither chrysalis +state nor any other change, but die, or we may call it dissolve +into their offspring, for there scarcely remains anything of them, +except a pruinous kind of down, after having given birth to the +young ones.</p> + +<p>Now we come to the practical deduction from these facts. It is +clear that the only time when the scalebug can emigrate and infest +a new tree is the time when it is a larva, that is, when it has the +power of locomotion. In countries with a pronounced winter this +time begins much later than with us, but it ends about the same +time, that is, the beginning of August. I have seen the male of +Aspidiotus in February, so that the active larva may be expected in +March, and the active Lecanium Hesperidum I have seen last year, +June 27, at Colonel Hooper's ranch in Sonoma County. We may safely +fix the time of the active scalebug from March to August.</p> + +<p>Notwithstanding the agility of the young scalebug, the voyage +from one tree to another, considering the minute size of the +traveler, is an undertaking but seldom succeeding, but one female +bug, if we take into account its enormous fertility, is sufficient +to cover with its grandchildren next year a tree of moderate +size.</p> + +<p>Besides there is another and much more effective way of +transmigration by the kind assistance of the ant who colonizes the +scalebug as well for its wax as it colonizes the Aphis for its +honey. Birds on their feathers and the gardener himself on his +dress contribute to spread them.</p> + +<p>But even the ant can not transplant the scalebug when it is once +firmly fixed by its rostrum.</p> + +<p>It is evident, therefore, that the time for the application of +insecticides is the time when all the scalebugs are fixed, that is +about the end of July or beginning of August. All previous +application will clean the tree or plant only for a time, and does +not prevent a more or less numerous immigration from the +neighboring vegetation, especially if an ant-hill is not far +off.</p> + +<p>As to the insecticide, there are to be applied two very +effective ones, each with its advantages and disadvantages.</p> + +<p>1. Petroleum and its different preparations.</p> + +<p>2. Lye or soap.</p> + +<p>The petroleum is the best disinfectant. It can safely be applied +to any cutting or stem, as long as it is not planted, but is one of +the most invidious substances when applied to vegetation in the +garden, or fields. If effectively applied, it can not be prevented +from running down the bark of the tree and entering the ground, +where every drop binds a certain amount of earth to an insoluble +substance, in which state it remains for ever. With every +application the quantity of these insoluble compounds is augmented +and sterility added.</p> + +<p>If I am not mistaken, it was near Antwerp--at least I am certain +it was in Belgium--where the first experience of this kind is +recorded.</p> + +<p>In France, preparations of coal tar have been recommended and +have been lately used in the form of a paint. May be that in this +form the substance is not so apt to enter into combinations with +the soil. At any rate, the method is of too recent a date to permit +any conclusions about the final result of these applications, as +the invidious nature of the substance produces, by gradual +accumulation, its effects, which are not perceived until they are +irreparable.</p> + +<p>2. Lye or soap. The application of these insecticides requires +more care, and is therefore more troublesome. But instead of +attracting fertility from the soil, they add to it. In Southern +Europe soap and water has been for many years the remedy against +the Lecanium Hesperidum. The method applied by the farmers in +Portugal, as described to me by Dr. Bleasdale, is perhaps the most +perfect one. The Portuguese have very well observed that the +colonization of scalebugs always begins at the lowest end of the +trunk and pretend, therefore, that the scalebug comes out of the +ground. This, of course, is not the case, but may their +interpretation be an error, they have been practical enough in +utilizing their observation about the invasion beginning near the +roots. They knead a ring of clay round the tree, in which ring the +soap water runs when they wash the tree, and besides, they fill +frequently the little ditch formed by this ring.</p> + +<p>This arrangement of course is only possible in climates of a +rainy summer.</p> + +<p>As it is our object to make our knowledge as available as +possible for practical purposes, I repeat for the benefit of +cultivators the advice, without repeating the reasoning:</p> + +<p>1. Use the petroleum for disinfecting imported trees and +cuttings:</p> + +<p>2. Use soap for cleaning trees planted in your orchard.</p> + +<p>3. If you must use the petroleum in your garden, use it in +August, when a single application is sufficient.</p> + +<hr> +<p><a name="25"></a></p> + +<h2>AGRICULTURAL ITEMS.</h2> + +<p>The exportation of dried apples from this country to France has +greatly increased of late years, and now it is said that a large +part of this useful product comes back in the shape of Normandy +cider and light claret.</p> + +<p>A.B. Goodsell says in the <i>New York Tribune</i>: "Put your hen +feed around the currants. I did this twice a week during May and +June, and not a currant worm was seen, while every leaf was eaten +off other bushes 150 feet distant, and not so treated."</p> + +<p>Buckwheat may be made profitable upon a piece of rough or newly +cleared ground: No other crop is so effective in mellowing rough, +cloddy land. The seed in northern localities should be sown before +July 12; otherwise early frosts may catch the crops. Grass and +clover may sometimes be sown successfully with buckwheat.</p> + +<p>The London News says: "Of all poultry breeding, the rearing of +the goose in favorable situations is said to be the least +troublesome and most profitable. It is not surprising, therefore, +that the trade has of late years been enormously developed. Geese +will live, and, to a certain extent, thrive on the coarsest of +grasses."</p> + +<p>When a cow has a depraved appetite, and chews coarse, +indigestible things, or licks the ground, it indicates indigestion, +and she should have some physic. Give one pint and a half of +linseed oil, one pound of Epsom salts, and afterward give in some +bran one ounce of salt and the same of ground ginger twice a +week.</p> + +<p>Asiatic breeds of fowl lay eggs from deep chocolate through +every shade of coffee color, while the Spanish, Hamburg, and +Italian breeds are known for the pure white of the eggshell. A +cross, however remote, with Asiatics, will cause even the +last-named breeds to lay an egg slightly tinted.</p> + +<p>In setting out currant bushes care should be exercised not to +place any buds under ground, or they will push out as so many +suckers. Currants are great feeders, and should be highly manured. +To destroy the worm, steep one table-spoonful of hellebore in a +pint of water, and sprinkle the bushes. Two or three sprinklings +are sufficient for one season.</p> + +<p>Mr. Joseph Harris, of Rochester, makes a handy box for +protecting melons and cucumbers from insect enemies. Take two +strips of board of the required size, and fasten them together with +a piece of muslin, so the muslin will form the top and two sides of +the box. Then stretch into box form by inserting a small strip of +wood as a brace between the two boards. This makes a good, +serviceable box, and, when done with for the season, it can be +packed into a very small space, by simply removing the brace and +bringing the two board sides together. As there is no patent on the +contrivance, anybody can make the boxes for himself.</p> + +<p>Mr. C. S. Read recently said before the London Fanners' Club: +"American agriculturists get up earlier, are better educated, breed +their stock more scientifically, use more machinery, and generally +bring more brains to bear upon their work than the English farmer. +The practical conclusion is, that if farmers in England worked +hard, lived frugally, were clad as meanly as those of the States, +were content to drink filthy tea three times a day, read more and +hunted less, the majority of them may continue to live in the old +country."--<i>N. E. Farmer</i>.</p> + +<hr> +<p><a name="26"></a></p> + +<h2>TIMBER TREES.</h2> + +<p>A paper was read by Sir R. Christison at the last meeting of the +Edinburgh Botanical Society upon the "Growth of Wood in 1880." In a +former paper, he said, he endeavored to show that, in the +unfavorable season of 1879, the growth of wood of all kinds of +trees was materially less than in the comparatively favorable +season of 1878. He had now to state results of measurements of the +same trees for the recent favorable season of 1880. The previous +autumn was unfavorable for the ripening of young wood, and the +trees in an unprepared condition were exposed during a great part +of December, 1879, to an asperity of climate unprecedented in this +latitude. This might have led one to expect a falling off in the +growth of wood, and it appeared, from comparison of measurements, +that, with very few exceptions, the growth of wood last year was +even more below the average of favorable years than that of the bad +year, 1879. Thus, in fifteen leaf-shedding trees of various +species, exclusive of the oak, the average growth of trunk girth in +three successive years was: 1878, 8-10ths; 1879, 45-100ths; 1880, +3-10ths and a half. In four specimens of the oak tribe, the growth +was: 1878, 8-10ths; 1879, 77-100ths; 1880, 54-100ths. In twenty +specimens of the evergreen Pinaceae the growth was: 1878, 8-10ths; +1879, 7-10ths; 1880, 6-10ths and a half. After giving details in +regard to particular trees, Sir Robert stated, as general +deductions from his observations, that leaf-shedding trees, +exclusive of the oak, suffered most; that the evergreen Pinaceae +suffered least; and that there was some power of resistance on the +part of the oak tribe which was remarkable, the power of resistance +of the Hungary oak being particularly deserving of attention. In +another communication on the "extent of the season of growth," Sir +Robert stated, as the result of observations on five leaf-shedding +and five evergreen trees, that in the case of the former, even in a +fine year, the growth of wood was confined very nearly, if not +entirely, to the months of June, July, and August; while in the +case of the latter growth commenced a month sooner, terminating, +however, about the same time. Mr. A. Buchan said it was proposed +that the inquiry should be taken up more extensively over +Scotland.</p> + +<hr> +<a name="28"></a> MEDICAL USES OF FIGS.--Prof. Bouchut speaks +(<i>Comptes Rendus</i>) of some experiments he has made, going to +show that the milky juice of the fig-tree possesses a digestive +power. He also observed that, when some of this preparation was +mixed with animal tissue, it preserved it it from decay for a long +time. This fact, in connection with Prof. Billroth's case of cancer +of the breast, which was so excessively foul smelling that all his +deodorizers failed, but which, on applying a poultice made of dried +figs cooked in milk, the previously unbearable odor was entirely +done away with, gives an importance to this homely remedy not to be +denied.--<i>Medical Press and Circ.</i> + +<hr> +<p><a name="27"></a></p> + +<h2>BLOOD RAIN.</h2> + +<p>The sensibilities of ignorant or superstitious people have at +various times been alarmed by the different phenomena of so-called +blood, ink, or sulphur rains. Ehrenberg very patiently collected +records of the most prominent instances of these, and published +them in his treatise on the dust of trade winds. Some, it is known, +are due to soot; others, to pollen of conifers or willows; others, +to the production of fungi and algae.</p> + +<p>Many of the tales of the descent of showers of blood from the +clouds which are so common in old chronicles, depends, says Mr. +Berkeley, the mycologist, upon the multitudinous production of +infusorial insects or some of the lower algae. To this category +belongs the phenomenon known under the name of "red snow." One of +the most peculiar and remarkable form, which is apparently virulent +only in very hot seasons, is caused by the rapid production of +little blood-red spots on cooked vegetables or decaying fungi, so +that provisions which were dressed only the previous day are +covered with a bright scarlet coat, which sometimes penetrates +deeply into their substance. This depends upon the growth of a +little plant which has been referred to the algae, under the name +of <i>Palmellae prodigiosa</i>. The rapidity with which this little +plant spreads over meat and vegetables is quite astonishing, making +them appear precisely as if spotted with arterial blood; and what +increases the illusion is, that there are little detached specks, +exactly as if they had been squirted from a small artery. The +particles of which the substance is composed have an active +molecular motion, but the morphosis of the production has not yet +been properly observed. The color of the so-called "blood rain" is +so beautiful that attempts have been made to use it as a dye, and +with some success; and could the plant be reproduced with any +constancy, there seems little doubt that the color would stand. On +the same paste with the "blood-rain" there have been observed +white, blue, and yellow spots, which were not distinguishable in +structure and character.</p> + +<hr> +<p><a name="29"></a></p> + +<h2>TOPICAL MEDICATION IN PHTHISIS.</h2> + +<p>Dr. G.H. Mackenzie reports in the <i>Lancet</i> an acute case of +phthisis which was successfully treated by him by causing the +patient to respire as continuously as possible, through a +respirator devised for the purpose, an antiseptic atmosphere. The +result obtained appears to bear out the experiments of +Schüller of Greifswald, who found that animals rendered +artificially tuberculous were cured by being made to inhale +creosote water for lengthened periods. Intermittent spraying or +inhaling does not produce the same result. In order to insure +success the application to the lungs must be made +<i>continuously</i>. For this purpose Dr. Mackenzie has used +various volatile antiseptics, such as creosote, carbolic acid, and +thymol. The latter, however, he has discarded as being too +irritating and inefficient. Carbolic acid seems to be absorbed, for +it has been detected freely in the urine after it had been inhaled; +but this does not happen with creosote. As absorption of the +particular drug employed is not necessary, and therefore not to be +desired, Dr. Mackenzie now uses creosote only, either pure or +dissolved in one to three parts of rectified spirits. "Whether," +says he, "the success so far attained is due to the antidotal +action of creosote and carbolic acid on a specific tubercular +neoplasm, or to their action as preventives of septic poisoning +from the local center in the lungs, it is certain that their +continuous, steady use in the manner just described has a decidedly +curative action in acute phthisis, and is therefore, worthy of an +extended trial."</p> + +<hr> +<p><a name="19"></a></p> + +<h2>ON THE LAW OF AVOGADRO AND AMPERE.</h2> + +<p>The Scientific American Supplement of May 14,1881, contains, +under this head, Mr. Wm. H. Greene's objections to my demonstration +(in No. 270 of the same paper) of the error of Avogadro's +hypothesis. The most important part of my argument is based on the +evidence afforded by the compound cyanogen; and Mr. Greene, +directing his attention to this subject in the first place, states +that because cyanogen combines with hydrogen or with chlorine, +without diminution of volumes, I have concluded that the hypothesis +falls to the ground. This statement has impressed me with the +conviction that Mr. Greene has failed to perceive the difficulty +which is at the bottom of the question, and I will, therefore, +present the subject more fully and comprehensively.</p> + +<p>The molecule of any elementary body is, on the ground of the +hypothesis, assumed to be a compound of two atoms, and the molecule +of carbon consequently C<sub>2</sub>=24; that of nitrogen +N<sub>2</sub>=28. Combination of the two, according to the same +hypothesis, takes place by substitution; the atoms are supposed to +be set free and to exchange places, forming a new compound +different from the original only in this: that each new particle +contains an atom of each of the two different substances, while +each original particle consists of two identical atoms. The product +is, therefore, assumed to be, and can, under the circumstances, be +no other than particles of the composition CN and weight 26. These +particles are molecules, according to the definition laid down, +just as C<sub>2</sub> and N<sub>2</sub>; but there is this +essential difference, that the specific gravity of cyanogen gas, +26, coincides with the molecular weight, while the assumed +molecular weight, N<sub>2</sub>=28, is twice as great as the +specific gravity of the gas, N=14.</p> + +<p>In using the term molecular weight, it is to be remembered that +it does not express the weight of single molecules, but only their +relative weight, millions of millions molecules being contained in +the unit of volume. But on the hypothesis that there is the same +number of molecules in the same volume of any gas, the specific +gravities of gases can be, and are, identified with their molecular +weights, and, on the ground of the hypothesis again, the unit of +the numbers which enter into every chemical reaction and constitute +the molecular weight, is stipulated to be that contained in two +volumes.</p> + +<p>The impossibility of the correctness of the hypothesis is now +revealed by the fact just demonstrated, that in the case of +nitrogen the specific gravity does not coincide with the molecular +weight. If equal volumes contain the same number of molecules, the +specific gravities and the molecular weights must be the same; and +if the specific gravities and molecular weights are not the same, +equal volumes cannot contain the same number of molecules. The +assumed molecular weight of nitrogen is twice as great as the +specific gravity, but the molecular weight and the specific gravity +of cyanogen are identical; the number of molecules contained in one +volume of cyanogen must, therefore, necessarily be twice as great +as the number contained in one of nitrogen, and this is fully and +completely borne out by the chemical facts.</p> + +<p>In saying that when cyanogen combines with chlorine there is +naturally no condensation, Mr. Greene has no idea that this natural +law is fatal to his artificial law of Avogadro and Ampere; "for," +continues he, "the theory is fulfilled by the actual reaction." It +is not. The theory requires two vols. of cyanogen and two vols. of +chlorine, that is, the unit of numbers, to enter into reaction and +to produce two vols. of the compound. But they produce four vols., +and the non-condensation is therefore in opposition to the theory. +It is true beyond doubt that the molecular weight of cyanogen +chloride is contained in two volumes, in spite of the hypothesis, +not on the ground of it; two vols. + two vols., producing four +vols.; two vols. could, theoretically, contain only half the unit +of numbers, and there seems to be no escape from the following +general conclusions:</p> + +<p>1. Two vols. of CNCl, representing the unit of numbers, the +constituent weights, C=12, N=14, Cl=35.5, must each, likewise, +represent the same number; the molecular weight is, therefore, +contained in one vol. of N or Cl, but in two of CNCl and equal +numbers are not contained in equal volumes.</p> + +<p>2. The weights N=14, Cl=35.5 occupy in the free state one +volume, but in the combination, CNCl, two volumes; their specific +gravity is, therefore, by chemical action reduced to one half. The +fact thus elicited of the variability and variation of the specific +gravity is of fundamental importance and involves the irrelevancy +of the mathematical demonstration of the hypothesis. In this +demonstration the specific gravity is assumed to be constant, and +this assumption not holding good, and the number of molecules in +unit of volume being reduced to one half when the specific gravity +is reduced to the same extent by chemical action, it is obvious +that the mathematical proof must fail. Mr. Greene states that I +have proceeded to demolish C. Clerk Maxwell's conclusion from +mathematical reasoning. This is incorrect; I have found no fault +with the conclusion of the celebrated mathematician, and consider +his reasoning unimpeachable. I am also of opinion that he is +entitled to great credit and respect for the prominent part he has +taken in the development of the kinetic theory, and further think +that it was for the chemists to produce the fact of the variability +of the specific gravities, which they would probably not have +failed to do but for the prevalence of Avogadro's hypothesis, which +is virtually the assertion of the constancy of the specific +gravities.</p> + +<p>3. The unit of numbers being represented by Cl=35.5, it is +likewise represented by H=1, and as the product of the union of the +two elements is HCl, 36.5 = two vols., combination takes place by +addition and not by substitution; consequently are</p> + +<p>4. The elementary molecules not compounds of atoms? And the +distinction between atoms and molecules is an artificial one, not +justified by the natural facts.</p> + +<p>5. Is the molecular weight not in every instance = two +volumes?</p> + +<p>These conclusions overthrow all the fundamental assumptions on +which the hypothesis rests, and leave it, in the full meaning of +the term, without support. Though Mr. Greene states that my +arguments are based upon entirely erroneous premises, he has not +even attempted to invalidate a single one of my premises.</p> + +<p>As he considers the non-condensation to be natural in the case +of cyanogen and chlorine, the condensation of two vols. of HCl + +two vols. of H<sub>3</sub>N to two vols. of NH<sub>4</sub>Cl ought +to appear to him unnatural. He, however, contends for it, and +tries, on this solitary occasion, to strengthen his opinion by +authority, though the proof, if it could be given, that ammonium +chloride at the temperature of volatilization is decomposed into +its two constituents, would be insufficient to uphold the +theory.</p> + +<p>The ground on which Mr. Greene assumes a partial decomposition +at 350° C. is the slight excess of the observed density (14.43) +over that corresponding to four vols. (13.375). There is, however, +a similar slight excess in the case of the vapor of ammonium +cyanide, the same values being respectively 11.4 and 11; and as +this compound is volatile at 100° C and, at the same time, is +capable to exist at a very high temperature, being formed by the +union of carbon with ammonia, nobody has ever, as far as I am +aware, maintained that it is completely or partially decomposed at +volatilization. The excess of weight not being due, therefore, to +such cause in this case, it cannot be due to it in the other.</p> + +<p>The question being whether the molecular weight of ammonium +chloride is two vols. or four vols., an idea of the magnitude of +the assumed decomposition is conveyed by the proportion of the +volume of the decomposed salt to the volume of the non-decomposed, +and Mr. Greene's quotation of the percentage of weight is +irrelevant and misleading, and his number not even correct. A +mixture containing</p> + +<pre> + 1.055 vols. of spec. gr. 26.75 = 28.22 and + 12.32 " " " " 13.375 = 164.78 + ------ ------ + 13.375 " 193 +</pre> + +<p>has the spec. gr. 193 / 13.375 = 14.43. The proportion in one +vol. of the undecomposed to the decomposed salt is, therefore, as 1 +to 11.68 and the percentage of volume of the former 0.0789, and +that of weight 28.22 / 193 = 0.146, and not 0.16.</p> + +<p>It is not easy to imagine why a small fraction of the heavy +molecules should be volatilized undecomposed, the temperature being +sufficient to decompose the great bulk. Marignac assumes, indeed, +partial decomposition, but the difficulties which he encountered in +making the experiments, on the results of which his opinion rests, +were so great that he himself accords to the numbers obtained by +him only the value of a rough approximation.</p> + +<p>The heat absorbed in volatilization will comprise the heat of +combination as well as of aggregation, if decomposition takes +place, and will therefore be the same as that set free at +combination. Favre and Silbermann found this to be 743.5 at +ordinary temperature, from which Marignac concludes that it would +be 715 for the temperature 350°; he found as the heat of +volatilization 706, but considers the probable exact value to be +between 617 and 818.[1]</p> + +<p>[Footnote 1: See <i>Comptes Rendus</i>, t. lxvii., p. 877.]</p> + +<p>An uncertainty within so wide a range does not justify the +confidence of Mr. Greene which he expresses in these words: "It is, +therefore, extremely probable that ammonium chloride is almost +entirely dissociated, even at the temperature of volatilization." +By Boettinger's apparatus a decomposition may possibly have been +demonstrated, but it remains to be seen whether it is not due to +some special cause.</p> + +<p>When Mr. Greene says that the relations between the physical +properties of solids and liquids and their molecular composition +can in no manner affect the laws of gases, nobody is likely to +dissent; but the conclusion that their discussion is foreign to the +question of the number of molecules in unit of volume does by no +means follow. If the specific gravity of a solid or the weight of +unit of volume represents a certain number of molecules, and is +found to occupy two volumes in a compound of the solid with another +solid, the number of molecules in one volume is reduced to one +half. This I have shown to be the case in a number of compounds, +and the decrease of the specific gravity with increase of the +complexity of composition appears to be a general law, as may be +concluded from the very low specific gravity of the most highly +organized compounds, for instance the fatty bodies, the molecules +of which, being composed of very many constituents, are of heavy +weight; and likewise the compounds which occur in combination with +water and without it, the simpler compound having invariably a +greater specific gravity than the one combined with water; for +instance:</p> + +<pre> + BaH_2O_2 sp. gr. 4.495 + " " + 8H_2O " 1.656 + S_2H_2O_2 " 3.625 + " " + 8H_2O " 1.396 + FeSO_4 " 3.138 + " + 7H_2O " 1.857 +</pre> + +<p>and so in every other case. This is now a recurrence of what +takes place in gases, and proves the fallacy of the hypothesis; for +if these compounds could be volatilized the vapor densities would +necessarily vary in the inverse proportion of the degree of +composition.</p> + +<p>The reproach that Berthelot has been endeavoring for nearly a +quarter of a century to hold back the progress of scientific +chemistry, is a great and unjustifiable misrepresentation of the +distinguished chemist and member of the Institute of France, who +has done so much for thermo-chemistry, and the more unfortunate as +it seems to serve only the purpose of a prelude to the following +sentences: "But Mr. Vogel cannot claim, as can Mr. Berthelot, any +real work or experiment, however roughly performed, suggested by +the desire to prove the truth of his own views. Let him not, then, +bring forth old and long since explained discrepancies, ... but +when he will have discovered new or overlooked facts ... chemists +will gladly listen." ... Mr. Greene is here no longer occupied to +investigate whether what I have said concerning Avogadro's +hypothesis is true or false, but with myself he has become +personal, and in noticing his remarks my sole object is to contend +against an error which is much prevalent. If, according to Mr. +Greene, the real work of science consists in experimenting, and +conclusions unsupported by our own experiments have no value, it +does not appear for what purpose he has published his answer to my +paper; an experiment of his, settling Marignac's uncertain results, +would have justified the reliance he places on them. The ground he +takes is utterly untenable. Experiments are necessary to establish +facts; without them there could be no science, and the highest +credit is due to those who perform successfully difficult or costly +experiments. Experimenting is, however, not the aim and object of +science, but the means to arrive at the truth; and discoveries +derived from accumulated and generally accepted facts are not the +less valuable on account of not having been derived from new and +special experiment.</p> + +<p>It is, further, far from true that the real work of science +consists in experimenting; mental work is not less required, and +the greatest results have not been obtained by experimenters, but +by the mental labor of those who have, from the study of +established facts, arrived at conclusions which the experimenters +had failed to draw. This is naturally so, because a great +generalization must explain all the facts involved, and can be +derived only from their study; but the attention of the +experimenter is necessarily absorbed by the special work he +undertakes. I refer to the three greatest events in science: the +discovery of the Copernican system, the three laws of Kepler, and +Newton's law of gravitation, none of which is due to direct and +special experimentation. Copernicus was an astronomer, but the +discovery of his system is due chiefly to his study of the +complications of the Ptolemaic system. Kepler is a memorable +witness of what can be accomplished by skillful and persistent +mental labor. "His discoveries were secrets extorted from nature by +the most profound and laborious research." The discovery of his +third law is said to have occupied him seventeen years. Newton's +great discovery is likewise the result of mental labor; he was +enabled to accomplish it by means of the laws of Kepler, the laws +of falling bodies established by Galileo, and Picard's exact +measurement of a degree of a meridian.</p> + +<p>If, then, mental work is as indispensable as experimental, it is +not less true that there are men more specially fitted for the one, +others for the other, and the best interests of science will be +served when experiments are made by those specially adapted, +skillful, and favorably situated, and the possibly greatest number +of men, able and willing to do mental work, engage in extracting +from the accumulated treasures of experimental science all the +results which they are capable to yield. Any truth discovered by +this means is clear gain, and saves the waste of time, labor, and +money spent in unnecessary experiment. Mr. Greene's zeal for +experiment and depreciation of mental work would be in order, if +ways and means were to be found to render the advancement of +science as difficult and slow as possible; they are decidedly not +in the interest of science, and can not have been inspired by a +desire for its promotion.</p> + +<p>As the evidence of the specific heats of the fallacy of +Avogadro's hypothesis involves lengthy explanations, the subject is +reserved for another paper.</p> + +<p>San Francisco, Cal., May, 1881.</p> + +<p>E. VOGEL.</p> + +<hr> +<p><a name="16"></a></p> + +<h2>DYEING REDS WITH ARTIFICIAL ALIZARIN.</h2> + +<h3>By M. MAURICE PRUD'HOMME.</h3> + +<p>Since several years, the methods of madder dyeing have undergone +a complete revolution, the origin of which we will seek to point +out. When artificial alizarin, thanks to the beautiful researches +of Graebe and Liebermann, made its industrial appearance in 1869, +it was soon found that the commercial product, though yielding +beautiful purples, was incapable of producing brilliant reds (C. +Koechlin). While admitting that the new product was identical with +the alizarin extracted from madder, we were led to conclude that in +order to produce fine Turkey reds, the coloring matters which +accompany alizarin must play an important part. This was the idea +propounded by Kuhlmann as far back as 1828 (<i>Soc. Ind. de +Mulhouse</i>, 49, p. 86). According to the researches of MM. +Schützenberger and Schiffert, the coloring matters of madder +are alizarin, purpurin, pseudopurpurin, purpuroxanthin, and an +orange matter, which M. Rosenstiehl considers identical with +hydrated purpurin. Subsequently, there have been added to the list +an orange body, purpuroxantho-carbonic acid of Schunck and Roemer, +identical with the munjistin found by Stenhouse in the madder of +India. It was known that purpuroxanthin does not dye; that +pseudopurpurin is very easily transformed into purpurin, and the +uncertainty which was felt concerning hydrated purpurin left room +merely for the hypothesis that Turkey-red is obtained by the +concurrent action of alizarin and purpurin. In the meantime, the +manufacture of artificial alizarin became extended, and a compound +was sold as "alizarin for reds." It is now known, thanks to the +researches of Perkin, Schunck, Roemer, Graebe, and Liebermann, that +in the manufacture of artificial alizarin there are produced three +distinct coloring matters--alizarin, iso or anthrapurpurin, and +flavopurpurin, the two latter being isomers of purpurin. We may +remark that purpurin has not been obtained by direct synthesis. M. +de Lalande has produced it by the oxidation of alizarin. Alizarin +is derived from monosulphanthraquinonic acid, on melting with the +hydrate of potassa or soda. It is a dioxyanthraquinone.</p> + +<p>Anthrapurpurin and flavopurpurin are obtained from two isomeric +disulphanthraquinonic acids, improperly named isoanthraflavic and +anthraflavic acids, which are converted into anthrapurpurin and +flavopurpurin by a more profound action of potassa. These two +bodies are trioxyanthraquinones.</p> + +<p>We call to mind that alizarin dyes reds of a violet tone, free +from yellow; roses with a blue cast and beautiful purples. +Anthrapurpurin and flavopurpurin differ little from each other, +though the shades dyed with the latter are more yellow. The reds +produced with these coloring matters have a very bright yellowish +reflection, but the roses are too yellow and the purples incline to +a dull gray.</p> + +<p>Experience with the madder colors shows that a mixture of +alizarin and purpurin yields the most beautiful roses in the steam +style, but it is not the same in dyeing, where the roses got with +fleur de garance have never been equaled.</p> + +<p>"Alizarins for reds" all contain more or less of alizarin +properly so-called, from 1 to 10 per cent., along with +anthrapurpurin and flavopurpurin. This proportion does not affect +the tone of the reds obtained further than by preventing them by +having too yellow a tone.</p> + +<p>The first use of the alizarins for reds was for application of +styles, that is colors containing at once the mordant and the +coloring matter and fixed upon the cloth by the action of steam. +Good steam-reds were easily obtained by using receipts originally +designed for extracts of madder (mixtures of alizarin and +purpurin). On the other hand, the first attempts at dyeing red +grounds and red pieces were not successful. The custom of dyeing up +to a brown with fleur and then lightening the shade by a succession +of soapings and cleanings had much to do with this failure. Goods, +mordanted with alumina and dyed with alizarin for reds up to +saturation, never reach the brown tone given by fleur or garancin. +This tone is due in great part to the presence of fawn colored +matters, which the cleanings and soapings served to destroy or +remove. The same operations have also another end--to transform the +purpurin into its hydrate, which is brighter and more solid. The +shade, in a word, loses in depth and gains in brightness. With +alizarins for reds, the case is quite different; they contain no +impurities to remove and no bodies which may gain brightness in +consequence of chemical changes under the influence of the +clearings and soapings. These have only one result, in addition to +the formation of a lake of fatty acid, that is to make the shades +lose in intensity. The method of subjecting reds got up with +alizarin to the same treatment as madder-reds was faulty.</p> + +<p>There appeared next a method of dyeing bases upon different +principles. The work of M. Schützenberger (1864) speaks of the +use of sulpho-conjugated fatty acids for the fixation of aniline +colors. In England, for a number of years, dyed-reds had been +padded in soap-baths and afterwards steamed to brighten the red. In +1867, Braun and Cordier, of Rouen, exhibited Turkey reds dyed in +five days. The pieces were passed through aluminate of soda at +18° B., then through ammonium chloride, washed, dyed with +garancin, taken through an oil-bath, dried and steamed for an hour, +and were finally cleared in the ordinary manner for Turkey-reds. +The oil-bath was prepared by treating olive-oil with nitric acid. +This preparation, invented by Hirn, was applied since 1846 by Braun +(Braun and Cordier). Since 1849, Gros, Roman, and Marozeau, of +Wesserling, printed fine furniture styles by block upon pieces +previously taken through sulpholeic acid. When the pieces were +steamed and washed the reds and roses were superior to the old dyed +reds and roses produced at the cost of many sourings and soapings. +Certain makers of aniline colors sold mixtures ready prepared for +printing which were known to contain sulpholeic acids. There was +thus an idea in the air that sulpholeic acid, under the influence +of steam, formed brilliant and solid lakes with coloring matters. +These facts detract in nothing from the merit of M. Horace +Koechlin, who combined these scattered data into a true discovery. +The original process may be summed up under the following heads: +Printing or padding with an aluminous mordant, which is fixed and +cleaned in the usual manner; dyeing in alizarin for reds with +addition of calcium acetate; padding in sulpholeic acid and drying; +steaming and soaping. The process was next introduced into England, +whence it returned with the following modifications; in place of +olive-oil or oleic acid, castor oil was used, as cheaper, and the +number of operations was reduced. Castor oil, modified by sulphuric +acid, can be introduced at once into the dye-beck, so that the +fixation of the coloring matter as the lake of a fatty acid is +effected in a single operation. The dyeing was then followed by +steaming and soaping.</p> + +<p>For red on white grounds and for red grounds, a mordant of red +liquor at 5° to 6° B. is printed on, with a little salt of +tin or nitro-muriate of tin. It is fixed by oxidation at 30° to +35° C., and dunged with cow-dung and chalk. The pieces are then +dyed with 1 part alizarin for reds at 10 per cent., ¼ to +½ oil for reds (containing 50 per cent.), 1-6th part acetate +of lime at 15° B., giving an hour at 70° and half an hour +at the same heat. Wash, pad in oil (50 to 100 grms. per liter of +water), dry on the drum, or better, in the hot flue, and steam for +three-quarters to an hour and a half. The padding in oil is +needless, if sufficient oil has been used in dyeing, and the pieces +may be at once dried and steamed. Wash and soap for three-quarters +of an hour at 60°. Give a second soaping if necessary. If there +is no fear of soiling the whites, dye at a boil for the last +half-hour, which is in part equal to steaming.</p> + +<p>Red pieces and yarns may be dyed by the process just given for +red grounds; or, prepare in neutral red oil, in the proportion of +150 grms. per liter of water for pieces and 15 kilos for 100 kilos +of yarns. For pieces, pad with an ordinary machine with rollers +covered with calico. Dry the pieces in the drum, and the yarn in +the stove. Steam three-quarters of an hour at 1½ atmosphere. +Mordant in pyrolignite of alumina at 10° B., and wash +thoroughly. Dye for an hour at 70°, and half an hour longer at +the same heat, using for 100 kilos of cloth or yarn 20 kilos +alizarin at 10 per cent., 10 kilos acetate of lime at 18° B., +and 5 kilos sulpholeic acid. Steam for an hour. Soap for a longer +or shorter time, with or without the addition of soda crystals. +There may be added to the aluminous mordant a little salt of tin to +raise the tone. Lastly, aluminate of soda may be used as a mordant +in place of red liquor or sulphate of alumina.</p> + +<p>Certain firms employ a so-called continuous process. The pieces +are passed into a cistern 6 meters long and fitted with rollers. +This dye-bath contains, from 3 to 5 grms. of alizarin per liter of +water, and is heated to 98°. The pieces take 5 minutes to +traverse this cistern, and, owing to the high temperature and the +concentration of the dye liquor, they come out perfectly dyed. Two +pieces may even be passed through at once, one above the other. As +the dye-bath becomes exhausted, it must be recruited from time to +time with fresh quantities of alizarin. The great advantage of this +method is that it economizes not merely time but coloring +matter.</p> + +<p>The quantity of acetate of lime to be employed in dyeing varies +with the composition of the mordant and with that of the water. +Schlumberger has shown that Turkey-red contains 4 molecules of +alumina to 3 of lime. Rosenstiehl has shown that alumina mordants +are properly saturated if two equivalents of lime are used for each +equivalent of alizarin, if the dyeing is done without oil. These +figures require to be modified when the oil is put into the dye +beck, as it precipitates the lime. Acetate of lime at 15° B., +obtained by saturating acetic acid with chalk and adding a slight +excess of acetic acid, contains about ¼ mol. acetate of +lime.--<i>Bulletin de la Société Chimique de +Paris.</i></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. 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