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| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:54:06 -0700 |
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| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 04:54:06 -0700 |
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diff --git a/18763-h/18763-h.htm b/18763-h/18763-h.htm new file mode 100644 index 0000000..70ded0c --- /dev/null +++ b/18763-h/18763-h.htm @@ -0,0 +1,4645 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> + +<html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1" /> + <title> + The Project Gutenberg eBook of Scientific American Supplement, December 30, 1882 + </title> + <style type="text/css"> +/*<![CDATA[ XML blockout */ +<!-- + p { margin-top: .75em; + text-align: justify; + margin-bottom: .75em; + } + h1,h2,h3 { + text-align: center; /* all headings centered */ + clear: both; + } + hr { width: 50%; + margin-top: 2em; + margin-bottom: 2em; + margin-left: auto; + margin-right: auto; + clear: both; + } + + table {margin-left: auto; margin-right: auto;} + + body{margin-left: 15%; + margin-right: 15%; + } + + img {border: 0;} + + .center {text-align: center;} + .smcap {font-variant: small-caps;} + .u {text-decoration: underline;} + .right {text-align: right;} + .left {text-align: left;} + .botright {text-align: right; vertical-align: bottom;} + + .caption {font-weight: bold;} + + .figcenter {text-align: center; margin-top: 1.5em; margin-bottom: 1.5em; margin-left: auto; margin-right: auto;} + + .fnanchor {vertical-align: super; font-size: .8em;} + + .note {margin-left: 2em; margin-right: 2em; + margin-top: 0em; margin-bottom: 1em;} + .overline {text-decoration: overline;} + + .toc1 {vertical-align: top; text-align: left;} + .toc2, .toc3, .tl {text-align: left; vertical-align: bottom;} + .tr {text-align: right;} + // --> + /* XML end ]]>*/ + </style> + </head> +<body> + + +<pre> + +The Project Gutenberg EBook of Scientific American Supplement, No. 365, +December 30, 1882, 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. 365, December 30, 1882 + +Author: Various + +Release Date: July 6, 2006 [EBook #18763] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC AMERICAN *** + + + + +Produced by David King, Juliet Sutherland and the Online +Distributed Proofreading Team at http://www.pgdp.net + + + + + + +</pre> + + + +<div class="center" style="margin-left: -10%; margin-right: -10%;"> +<a href="images/title.png"><img src="images/title_th.png" width="800" alt="Issue Title" /></a> +</div> + + +<h1>SCIENTIFIC AMERICAN SUPPLEMENT NO. 365</h1> + + + +<h2>NEW YORK, DECEMBER 30, 1882.</h2> + +<h4>Scientific American Supplement. Vol. XIV., No. 365.</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="3" align="center">TABLE OF CONTENTS.</th> +</tr> +<tr><td colspan="2"> </td><td>PAGE.</td> +</tr> +<tr> +<td class="toc1">I.</td> +<td class="toc2"><a href="#art01"> +ENGINEERING AND MECHANICS.—Louis Favre, Constructor +of the St. Gothard Tunnel.—2 figures.—Portrait and +monument at Turin to commemorate the tunneling of the +Alps</a></td> +<td class="toc3">5817</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art02"> +The New Harbor of Vera Cruz.—New artificial harbor +for Vera Cruz.—Capt. Eads's plan.—1 figure.—Plan +of harbor and improvement</a></td> +<td class="toc3">5818</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art03"> +Cost of Power to Make Flour</a></td> +<td class="toc3">5818</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art04"> +Driving gear Mechanism for Lift Hammers.—2 figures</a></td> +<td class="toc3">5819</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art05"> +De Junker and Ruh's Machine for Cutting Annular +Wheels.—3 figures</a></td> +<td class="toc3">5819</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art06"> +Recent Hydraulic Experiments.—Results of experiments +on the flow of water in the Ganges Canal</a></td> +<td class="toc3">5819</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art07"> +The Germ: Shall It be Retained in Flour? By <span class="smcap">Arthur +Atkins</span></a></td> +<td class="toc3">5820</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art08"> +Wheat Tests</a></td> +<td class="toc3">5820</td> +</tr> +<tr> +<td class="toc1">II.</td> +<td class="toc2"><a href="#art09"> +TECHNOLOGY AND CHEMISTRY.—Apparatus for Manufacturing +Gaseous or Aerated Beverages.—11 figures.—Bicarbonate +of soda apparatus. Generator. Washer.—Suction +pump.—Saturator.—Apparatus for using carbonate of +lime.—Apparatus completely mechanical in operation</a></td> +<td class="toc3">5815</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art10"> +Detection and Estimation of Fusel Oil</a></td> +<td class="toc3">5816</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art11"> +On Silicon.—Curious formation of silicide of platinum</a></td> +<td class="toc3">5816</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art12"> +Stannous Nitrates.—The formation of explosive +compounds in machines by the corrosion of bronze and +tin solder</a></td> +<td class="toc3">5816</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art13"> +Metallic Thorium. By <span class="smcap">L.F. Nilson</span></a></td> +<td class="toc3">5816</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art14"> +Friedrich Wöhler.—Obituary notice of the great German +chemist</a></td> +<td class="toc3">5816</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art15"> +Apparatus for Printing by the Blue Process. By +<span class="smcap">Channing Whitaker</span>.—3 figures</a></td> +<td class="toc3">5820</td> +</tr> +<tr> +<td class="toc1">III.</td> +<td class="toc2"><a href="#art16"> +ELECTRICITY, LIGHT, HEAT, ETC.—Spectrum Gratings</a></td> +<td class="toc3">5822</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art17"> +A New Pocket Opera Glass.—4 figures</a></td> +<td class="toc3">5822</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art18"> +Atoms, Molecules, and Ether Waves. By <span class="smcap">John Tyndall</span>. +Action of heat and light on molecules.—Heat as an +agent in exploring molecular conditions.—The results +of a recent incursion into the extra-sensible world +of atoms and molecules</a></td> +<td class="toc3">5823</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art19"> +Apparatus for Measuring Electricity at the Upper +School of Telegraphy. By <span class="smcap">E. Mercadier</span>.—5 figures. +Constant vibrator.—The Electrical tuning fork. +Arrangement for testing electric piles.—Very rapid +electric tuning fork.—A vibrating micrometer</a></td> +<td class="toc3">5824</td> +</tr> +<tr> +<td class="toc1">IV.</td> +<td class="toc2"><a href="#art20"> +NATURAL HISTORY.—Our Origin as a Species. By <span class="smcap">Richard +Owen</span>.—The Neanderthal skull.—Differential characters +between the lowest _Homo_ and the highest _Simia_</a></td> +<td class="toc3">5825</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art21"> +The Aba or Odika. By <span class="smcap">Dr. W.H. Bacheler</span>.—A remarkable +tree of West Africa</a></td> +<td class="toc3">5826</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art22"> +California Cedars</a></td> +<td class="toc3">5826</td> +</tr> +<tr> +<td class="toc1"></td> +<td class="toc2"><a href="#art23"> +Ancient Greek Painting. (Transcriber's Note: Added to Table of Contents.)</a></td> +<td class="toc3">5822</td> +</tr> +</table> + +<hr style='width: 45%;' /> + + +<h2><a name="Page_5815" id="Page_5815"/><a name="art09" id="art09"/> +APPARATUS FOR MANUFACTURING GASEOUS OR AERATED BEVERAGES.</h2> + +<p>The apparatus employed at present for making gaseous +beverages are divided into two classes—intermittent apparatus +based on chemical compression, and continuous ones +based on mechanical compression.</p> + +<p>The first are simple in appearance and occupy small space, +but their use is attended with too great inconveniences and +losses to allow them to be employed in cases where the +manufacture is of any extent, so the continuous apparatus +are more and more preferred by those engaged in the industry.</p> + +<p>Continuous apparatus, however, other than those that we +now propose to occupy ourselves with, are not without some +defects, for the gas is produced in them intermittingly and +at intervals, and more rapidly than it is used, thus necessitating +the use of a gasometer, numerous and large washers, +complicated piping, and, besides, of an acid cock.</p> + +<p>To get rid of such drawbacks, it became necessary to seek +a means of rendering the production of the gas continuous, +and of regulating it automatically without the aid of the +operator. Mr. Mondollot has obtained such a result +through a happy modification of the primitive system of the +English engineer Bramah. He preserves the suction and +force pump but, while applying it to the same uses, he likewise +employs it, by the aid of a special arrangement, so as +to distribute the sulphuric acid automatically over the chalk +in the generator, and to thus obtain a regular and continuous +disengagement of carbonic acid gas. The dangers and +difficulties in the maneuver of an acid cock are obviated, the +gasometer and its cumbersome accessories are dispensed +with, and the purification is more certain, owing to the regularity +with which the gas traverses the washers.</p> + +<div class="figcenter" style="width: 600px;"> +<a href="images/fig9-1.png"> +<img src="images/fig9-1-small.png" width="600" height="402" alt="" title="" /> +</a> +<span class="caption">APPARATUS FOR MANUFACTURING GASEOUS BEVERAGES.</span></div> + +<p>In the accompanying plate we have figured three types of +these apparatus. The first that we shall describe is arranged +for the use of bicarbonate of soda. This apparatus +consists (1) of a <i>generator</i>, C D, (2) of a double <i>washer</i> G G, +(3) of a <i>suction pump</i>, P, and (4) of a <i>saturator</i>, S (See Figs +1 to 9).</p> + +<p><i>The Generator.</i>—This consists of a cylindrical leaden +receptacle, D, on the bottom of which rests a leaden bell containing +apertures, <i>c</i>, at its base. A partition, <i>c</i>, into which +is screwed a leaden tube, C, containing apertures divides the +interior of the bell into two compartments. The upper of +these latter is surmounted by a mouth, B, closed by a clamp, +and through which the bicarbonate of soda is introduced. +A definite quantity of water and sulphuric acid having been +poured into the receptacle, D, a level tends to take place between +the latter and the bell, C, the liquid passing through + +the apertures. But the acidulated water, coming in contact +with the soda, sets free carbonic acid gas, which, having no +exit, forces the water back and stops the production of gas +until the apparatus is set in motion. At this moment, the +suction of the pump causes a new inflow of acidulated water +upon the soda, from whence another disengagement of gas, +and then a momentary forcing of the water, whose level +thus alternately rises and falls and causes a continuous production +of gas proportionate with the suction of the pump.</p> + +<p>The consumption of soda and acid is about 2 kilogrammes +each for charging 100 siphons or 150 bottles. The bicarbonate +is known to be used up when the liquid in the generator +is seen to descend to the bottom of the water level, <i>n</i>, +fixed to the vessel, D.</p> + +<p><i>The Washer</i> (Figs 1 and 4)—The gas, on leaving the +generator, enters the washer through a bent copper pipe, R. +The washer is formed of two ovoid glass flasks G G, mounted +on a bronze piece, L, to which they are fixed by screw rings, <i>l</i>, +of the same metal. The two flasks, G G, communicate with +each other only through the tinned-copper tube <i>q</i>, which is +held in the mounting <i>q</i>, of the same metal. This latter is +screwed into the piece, L, and contains numerous apertures, +through which the gas coming in from the pipe, R, passes to +reach the upper flask, G. The gas is washed by bubbling +up through water that has been introduced through the cock, R. +After it has traversed both flasks, it escapes through the +copper pipe, <i>p</i>, into which it is sucked by the pump, P.</p> + +<p><i>The Pump</i> (Figs 1, 5 and 6)—This consists of a cylindrical +chamber, P, of bronze, bolted to a bracket on the frame, +and cast in a piece, with the suction valve chamber, P, in +which the valve, p, plays. It is surmounted by the distributing +valve chamber P<sup>2</sup>. This latter is held by means +of two nuts screwed on to the extremity of the rods, p<sup>3</sup>, +connected with the shell, E, of the distributing-cock, E. In the +shell, E, terminates, on one side, the pipe, <i>p</i>, through which +enters the gas from the washer, and, on the other, the pipe <i>i</i>, +that communicates with a feed-reservoir not shown in the +cuts. The cock E, permits of the simultaneous regulation +of the entrance of the gas and water. Its position is shown +by an index <i>e</i>, passing over a graduated dial, <i>e</i>. From the +distributing valve chamber, P<sup>2</sup> the pipe, <i>s</i>, leads the mixture +of water and gas under pressure into</p> + +<p><i>The Saturator</i>, S (Figs 1, 7 and 9)—This consists of a large +copper vessel, <i>s</i>, affixed to the top of the frame through the +intermedium of a bronze collar <i>h</i>, and a self closing bottom +H. This latter is provided with two pipes, one of which, <i>s</i>, +leads the mixture of water and carbonic acid forced by the +pump, and the other, <i>b</i>, communicates with the siphons or +bottles to be filled. The pipe, <i>b</i>, is not affixed directly to the +bottom, but is connected therewith through the intermedium + +of a cock, <i>r</i>. The object of the broken form of this pipe is to +cause the pressure to act according to the axis of the screw, +<i>r</i>, which is maneuvered by the key, <i>r</i><sup>2</sup>.</p> + +<p>The water under pressure, having been forced into the +vessel, S, is submitted therein to an agitation that allows it +to dissolve a larger quantity of gas. Such agitation is produced +by two pairs of paddles, J J, mounted at the extremity +of an axle actuated by the wheel, A, through the intermedium +of gearings, <i>g</i> and <i>g</i>.</p> + +<p>The course of the operation in the saturator may be followed +by an inspection of the water level, <i>n</i>, seen at the front +and side in Figs. 2 and 3. This apparatus, in which the +pressure reaches 4 to 6 atmospheres in the manufacture of +Seltzer water or gaseous lemonade in bottles, and from 10 +to 12 atmospheres in that of Seltzer water in siphons, is +provided also with a pressure gauge, <i>m</i>, and a safety valve, +both screwed, as is also the tube, <i>n</i><sup>2</sup>, into a sphere, S, on the +top of the saturator.</p> + +<p><i>Apparatus for Using Carbonate of Lime</i> (Figs 2, 3, +and 10)—When chalk is acted upon by sulphuric acid, there is +formed an insoluble sulphate which, by covering the chalk, +prevents the action of the acid from continuing if care be +not taken to constantly agitate the materials. This has led +to a change in the arrangement of the generator in the +apparatus designed for the use of chalk.</p> + +<p>It consists in this case of a leaden vessel, D, having a +hemispherical bottom set into a cylindrical cast iron base, K, +and of an agitator similar to that shown in Fig. 11, for +keeping the chalk in suspension in the water. These latter +materials are introduced through the mouth, B (Fig. 3). +Then a special receptacle, C, of lead, shown in detail in +Fig. 10, and the cock, <i>c</i>, of which is kept closed, is filled with +sulphuric acid. The acid is not introduced directly into the +vessel, C, but is poured into the cylinder, C, whose sides contain +numerous apertures which prevent foreign materials +from passing into the siphon tube <i>c</i>, and obstructing it.</p> + +<p>To put the apparatus in operation, the acid cock, <i>c</i>, is +opened and the wheel, A, is turned, thus setting in motion +both the pump piston, P, and the agitator, within S and D. +Then the play of the pump produces a suction in the +washers and from thence in the generator and causes the +acid in the vessel, C, to flow into the generator through the +leaden siphon tubes, <i>c</i>. Coming in contact with the chalk +in suspension, the acid produces a disengagement of gas +which soon establishes sufficient pressure to stop the flow of +the acid and drive it back into the siphon tube. The play +of the pump continuing, a new suction takes place and +consequently a momentary flow of acid and a new disengagement +of gas. Thus the production of the latter is continuous, +and is regulated by the very action of the pump, +<a name="Page_5816" id="Page_5816"/> +without the operator having to maneuver an acid-cock. +The latter he only has to open when he sets the apparatus in +operation, and to close it when he stops it.</p> + +<p>The arrangement of the washer is the same as in the preceding +apparatus, save that a larger cylindrical copper +reservoir, G', is substituted for the lower flask. The pump +and saturator offer nothing peculiar.</p> + +<p>A bent tube, <i>u</i>, which communicates with the generator, D, +on one side, and with a cylindrical tube, V, ending in a glass +vessel on the other, serves as a safety-valve for both the +generator and the acid vessel.</p> + +<p>The consumption of chalk is about 2.5 kilogrammes, and +the same of acid, for charging 100 siphons or 150 bottles. +The apparatus shown in the figure is capable of charging +600 siphons or 900 bottles per day.</p> + +<p><i>An Apparatus Completely Mechanical in Operation</i> +(Fig. 11).—This apparatus consists of two very distinct +parts. The saturator, pump, and driving shaft are supported +by a hollow base, in whose interior are placed a copper +washer and the water-inlet controlled by a float-cock. +This part of the apparatus is not shown in the plate. The +generator, partially shown in Fig. 11, is placed on a base of +its own, and is connected by a pipe with the rest of the +apparatus. It consists of two similar generators, D, made +of copper lined with lead, and working alternately, so as to +avoid all stoppages in the manufacture when the materials +are being renewed. The pipe, <i>d</i>, connecting the two parts of +the apparatus forks so as to lead the gas from one or the +other of the generators, whence it passes into the copper +washer within the base, then into the glass indicating +washer, and then to the pump which forces it into the +saturator.</p> + +<p>Each of the generators communicates by special pipes, +<i>a</i>, with a single safety vessel, V, that operates the same +as in the preceding apparatus. The agitator, Q, is of +bronze, and is curved as shown in Fig. 11.</p> + +<p>The production of this type of apparatus is dependent +upon the number of siphons that can be filled by a siphon +filler working without interruption.—<i>Machines, Outils et +Appareils.</i></p> + +<hr /> + +<h2><a name="art10" id="art10"/>DETECTION AND ESTIMATION OF FUSEL OIL.</h2> + +<p>Until quite recently we have had no accurate method for +the determination of fusel oil in alcohol or brandy. In 1837 +Meurer suggested a solution of one part of silver nitrate in +nine parts of water as a reagent for its detection, stating that +when added to alcohol containing fusel oil, a reddish brown +color is produced, and in case large quantities are present, a +dark brown precipitate is formed. It was soon found, however, +that other substances than amyl alcohol produce brown +colored solutions with silver nitrate; and Bouvier<a name="FNanchor_1_1"></a><a href="#Footnote_1_1"><sup>1</sup></a> observed +that on adding potassium iodide to alcohol containing fusel +oil, the solution is colored yellow, from the decomposition of +the iodide. Subsequently Böttger<a name="FNanchor_1_2"></a><a href="#Footnote_1_2"><sup>2</sup></a> proved that potassium +iodide is not decomposed by pure amyl alcohol, and that the +decomposition is due to the presence of acids contained in +fusel oil. More accurate results are obtained by using a +very dilute solution of potassium permanganate, which is +decomposed by amyl alcohol much more rapidly than by +ethyl alcohol.</p> + +<p>Depré<a name="FNanchor_1_3"></a><a href="#Footnote_1_3"><sup>3</sup></a> determines fusel oil by oxidizing a definite quantity +of the alcohol in a closed vessel with potassium bichromate +and sulphuric acid. after removal of excess of the +oxidizing reagents, the organic acids are distilled, and, by +repeated fractional distillation, the acetic acid is separated +as completely as possible. The remaining acids are saturated +with barium hydroxide, and the salts analyzed; a difference +between the percentage of barium found and that of +barium in barium acetate proves the presence of fusel oil, +and the amount of difference gives some idea of its quantity. +Betelli<a name="FNanchor_1_4"></a><a href="#Footnote_1_4"><sup>4</sup></a> dilutes 5 c.c. of the alcohol to be tested with 6 to 7 +volumes of water, and adds 15 to 20 drops of chloroform and +shakes thoroughly. If fusel oil is present, its odor may be +detected by evaporating the chloroform; or, by treatment +with sulphuric acid and sodium acetate, the ether is obtained, +which can be readily recognized. Jorissen<a name="FNanchor_1_5"></a><a href="#Footnote_1_5"><sup>5</sup></a> tests for +fusel oil by adding 10 drops of colorless aniline and 2 to 3 drops +of hydrochloric acid to 10 c.c. of the alcohol. In the presence +of fusel oil a red color is produced within a short time, +which can be detected when not more than 0.1 per cent. is +present. But Foerster<a name="FNanchor_1_6"></a><a href="#Footnote_1_6"><sup>6</sup></a> objects to this method because he +finds the color to be due to the presence of furfurol, and that +pure amyl alcohol gives no color with aniline and hydrochloric +acid.</p> + +<p>Hager<a name="FNanchor_1_7"></a><a href="#Footnote_1_7"><sup>7</sup></a> detects fusel oil as follows: If the spirit contains +more than 60 per cent. of alcohol, it is diluted with an equal +volume of water and some glycerine added, pieces of filter +paper are then saturated with the liquid and exposed to the +After the evaporation of the alcohol, the odor of the +fusel oil can be readily detected. For the quantitative determination +he distills 100 c.c. of the alcohol in a flask of +150 to 200 c.c. capacity connected with a condenser, and so arranged +that the apparatus does not extend more than 20 cm. +above the water bath. This arrangement prevents the fusel oil +from passing over. If the alcohol is stronger than 70 per cent., +and the height of the distillation apparatus is not more than +17 cm., the residue in the flask may be weighed as fusel oil. +With a weaker alcohol, or an apparatus which projects further +out of the water bath, the residual fusel oil is mixed +with water. It can, however, be separated by adding strong +alcohol and redistilling, or by treating with ether, which dissolves +the amyl alcohol, and distilling, the temperature being +raised finally to 60°.</p> + +<p>Marquardt,<a name="FNanchor_1_8"></a><a href="#Footnote_1_8"><sup>8</sup></a> like Betelli, extracts the fusel oil from alcohol +by means of chloroform, and by oxidation converts it into +valeric acid. From the quantity of barium valerate found +he calculates the amount of amyl alcohol present in the original +solution; 150 c.c. of the spirit, which has been diluted +so as to contain 12 to 15 per cent. of alcohol, are shaken up +thoroughly with 50 c.c. of chloroform, the aqueous layer +drawn off, and shaken with a fresh portion of chloroform. +This treatment is repeated several times. The extracts are +then united, and washed repeatedly with water. The chloroform, +which is now free from alcohol and contains all the +fusel oil, is treated with a solution of 5 grammes of potassium +bichromate in 30 grammes of water and 2 grammes of +sulphuric acid, and then heated in a closed flask for six hours +on a water bath at 85°. The contents of the flask are then distilled, +the distillate saturated with barium carbonate, and the +chloroform distilled; the residue is evaporated to a small volume, +the excess of barium carbonate filtered off, and the filtrate +evaporated to dryness and weighed. The residue is dissolved + +in water, a few drops of nitric acid added, and the +solution divided into two portions. In the first portion the +barium is determined; in the second the barium chloride. +The total per cent. of barium minus that of barium chloride +gives the amount present as barium valerate, from which is +calculated the per cent. of amyl alcohol. By this process +the author has determined one part of fusel oil in ten thousand +of alcohol. To detect very minute quantities of fusel +oil, the chloroform extracts are treated with several drops of +sulphuric acid and enough potassium permanganate to keep +the solution red for twenty-four hours. If allowed to stand +in a test tube, the odor of valeric aldehyde will first be noticed, +then that of amyl valerate, and lastly that of valeric +acid.—<i>Amer. Chem. Journal.</i></p> + +<p><a name="Footnote_1_1"/><a href="#FNanchor_1_1">[1]</a></p><div class="note"><p>Zeitschrift f. Anal. Chem. xi., 343.</p></div> + +<p><a name="Footnote_1_2"/><a href="#FNanchor_1_2">[2]</a></p><div class="note"><p>Dingler's Polytech. Jour., ccxii., 516.</p></div> + +<p><a name="Footnote_1_3"/><a href="#FNanchor_1_3">[3]</a></p><div class="note"><p>Pharm. J. Trans. [3] vi., 867.</p></div> + +<p><a name="Footnote_1_4"/><a href="#FNanchor_1_4">[4]</a></p><div class="note"><p>Berichte d. Deutschen Chem. Gesellsch., viii., 72.</p></div> + +<p><a name="Footnote_1_5"/><a href="#FNanchor_1_5">[5]</a></p><div class="note"><p>Pharm. Centralhalle, xxii., 3.</p></div> + +<p><a name="Footnote_1_6"/><a href="#FNanchor_1_6">[6]</a></p><div class="note"><p>Berichte d. Deutsch. Chem. Gesellsch., xv., 230.</p></div> + +<p><a name="Footnote_1_7"/><a href="#FNanchor_1_7">[7]</a></p><div class="note"><p>Pharm. Centralhalle, xxii., 236.</p></div> + +<p><a name="Footnote_1_8"/><a href="#FNanchor_1_8">[8]</a></p><div class="note"><p>Berichte d. Deutsch. Chem. Gesellsch., xv., 1,370 and 1,663.</p></div> + +<hr /> + +<h2><a name="art11" id="art11"/>ON SILICON.</h2> + +<p>It is known that platinum heated in a forge fire, in contact +with carbon, becomes fusible. Boussingault has shown +that this is due to the formation of a silicide of platinum by +means of the reduction of the silica of the carbon by the +metal. MM. P. Schützenberger and A. Colson have produced +the same phenomenon by heating to white heat a slip +of platinum in the center of a thick layer of lampblack free +from silica.</p> + +<p>The increase in weight of the metal and the augmentation +of its fusibility were found to be due, in this case also, to a +combination with silicon. As the silicon could not come +directly from the carbon which surrounded the platinum, +MM. Schützenberger and Colson have endeavored to discover +under what form it could pass from the walls of the +crucible through a layer of lampblack several centimeters in +thickness, in spite of a volatility amounting to almost +nothing under the conditions of the experiment. They describe +the following experiments as serving to throw some light +upon the question:</p> + +<p>1. A thin slip of platinum rolled in a spiral is placed in a +small crucible of retort carbon closed by a turned cover of +the same material. This is placed in a second larger crucible +of refractory clay, and the intervening space filled with +lampblack tightly packed. The whole is then heated to +white heat for an hour and a half in a good wind furnace. +After cooling, the platinum is generally found to have been +fused into a button, with a marked increase in weight due to +taking up silicon, which has penetrated in the form of vapor +through the walls of the interior crucible.</p> + +<p>2. If, in the preceding experiment, the lampblack be replaced +by a mixture of lampblack and rutile in fine powder, +the slip of platinum remains absolutely intact, and does not +change in weight. Thus the titaniferous packing recommended +by Sainte-Claire Deville for preventing the access of +nitrogen in experiments at high temperatures also prevents +the passage of silicon. A mixture of carbon and finely +divided iron is, on the contrary, ineffectual. These facts +seem to indicate that nitrogen plays a part in the transportation +of the silicon, as this is only prevented by the +same means made use of in order to prevent the passage of +nitrogen.</p> + +<p>3. The volatility of free silicon at a high temperature is +too slight to account for the alteration of the platinum at a +distance. This can be shown by placing several decigrammes +of crystallized silicon on the bottom of a small crucible of +retort carbon, covering the silicon with a small flat disk of +retort carbon upon which is placed the slip of platinum. +The crucible, closed by its turned cover, is then enveloped in +a titaniferous packing and kept at a brilliant white heat for +an hour and a half. The metal is found to have only very +slightly increased in weight, and its properties remain unaltered. +This experiment was repeated several times with the +same result. If, however, the crystallized silicon be replaced +by powdered calcined silica, the platinum, placed upon the +carbon disk, fuses and increases in weight, while the silica +loses weight. The theory of these curious phenomena is +very difficult to establish on account of the high temperatures +which are necessary for their manifestation, but it may +be concluded, at present, that nitrogen and probably oxygen +also play some part in the transportation of the silicon across +the intervening space, and that the carbosilicious compounds +recently described by MM. Schützenberger and Colson also +take part in the phenomenon.—<i>Comptes Rendus</i>, xciv., +1,710.—<i>Amer. Chem. Journal.</i></p> + +<hr /> + +<h2><a name="art12" id="art12"/>STANNOUS NITRATES.</h2> + +<p>At the Royal Powder Works at Spandau, Prussia, frequent +ignition of the powder at a certain stage of the process +led to an examination of the machinery, when it was +found that where, at certain parts, bronze pieces which were +soldered were in constant contact with the moist powder, +the solder was much corroded and in part entirely destroyed, +and that in the joints had collected a substance which, on +being scraped out with a chisel, exploded with emission of +sparks. It was suspected that the formation of this explosive +material was in some way connected with the corrosion of +the solder, and the subject was referred for investigation to +Rudolph Weber, of the School of Technology, at Berlin. +The main results of his investigation are here given.</p> + +<p>The explosive properties of the substance indicated a +probable nitro-compound of one of the solder metals (tin +and lead), and as the lead salts are more stable and better +understood than those of tin, it was resolved to investigate +the latter, in hope of obtaining a similar explosive compound. +Experiments on the action of moist potassium nitrate +on pure tin led to no result, as no explosive body was +formed. Stannous nitrate, Sn(NO<sub>3</sub>)<sub>2</sub>, formed by the action +of dilute nitric acid on tin, has long been known, but only in +solution, as it is decomposed on evaporating. By adding +freshly precipitated moist brown stannous oxide to cool nitric +acid of sp. gr. 1.20, as long as solution occurred, and +then cooling the solution to -20°, Weber obtained an abundance +of crystals of the composition Sn(NO<sub>3</sub>)<sub>2</sub> + 20H<sub>2</sub>O. +They resemble crystals of potassium chlorate. They cannot +be kept, as they liquefy at ordinary temperatures. An insoluble +<i>basic</i> salt was obtained by digesting an excess of moist +stannous oxide in solution of stannous nitrate, or by adding +to a solution of stannous nitrate by degrees, with constant +stirring, a quantity of sodium carbonate solution insufficient +for complete precipitation. Thus obtained, the basic salt, +which has the composition Sn<sub>2</sub>N<sub>2</sub>O<sub>7</sub>, is a snow-white +crystalline powder, which is partially decomposed by water, and +slowly oxidized by long exposure to the air, or by heating +to 100°. By rapid heating to a higher temperature, as well +as by percussion and friction, it explodes violently, giving +off a shower of sparks. This compound is also formed when +a fine spray of nitric acid (sp. gr. 1.20) is thrown upon a surface +of tin or solder. It is also formed when tin or solder is +exposed to the action of a solution of copper nitrate, and +thus formed presents the properties already described.</p> + +<p>In this, then, we have a probable cause of the explosions +occurring in the powder works; but the explanation of the + +formation of the substance is wanting, as potassium nitrate +was shown not to give an explosive substance with tin. A +thin layer of a mixture of sulphur and potassium nitrate +was placed between sheets of tin and copper foil, and +allowed to stand, being kept constantly moist. After a time +the copper was found to have become coated with sulphide, +while the tin was largely converted into the explosive basic +nitrate. The conditions are obviously the same as those +found in the powder machinery, where bronze and tin solder +are constantly in contact with moist gunpowder. The chemical +action is probably this: the sulphur of the powder forms, +with the copper of the bronze, copper sulphide; this is oxidized +to sulphate, which reacts with the niter of the powder, +forming potassium sulphate and copper nitrate; the latter, +as shown above, then forms with the tin of the solder the +explosive basic nitrate, which, being insoluble, gradually +collects in the joints, and finally leads to an explosion.—<i>Journal +für Praktische Chemie.</i></p> + +<hr /> + +<h2><a name="art13" id="art13"/>METALLIC THORIUM.</h2> + +<h3><span class="smcap">By L.F. Nilson.</span></h3> + +<p>The density of thorium as obtained by reducing the anhydrous +chloride by means of sodium was found by Chydenius, +7.657 to 7.795. The author has obtained metallic +thorium by heating sodium with the double anhydrous +thorium potassium chloride, in presence of sodium chloride +in an iron crucible. After treating the residue with water +there remains a grayish, heavy, sparkling powder, which +under the microscope appears to consist of very small crystals. +Metallic thorium is brittle and almost infusible; the +powder takes a metallic luster under pressure, is permanent +in the air at temperatures up to 120°, takes +fire below a red heat either in air or oxygen, and +burns with a dazzling luster, leaving a residue +of perfectly white thoria. If heated with chlorine, +bromine, iodine, and sulphur, it combines with them with +ignition. It is not attacked by water, cold or hot. Dilute +sulphuric acid occasions the disengagement of hydrogen, +especially if heated, but the metal is acted on very slowly. +Concentrated sulphuric acid with the aid of heat attacks the +metal very slightly, evolving sulphurous anhydride. Nitric +acid, strong or weak, has no sensible action. Fuming hydrochloric +acid and <i>aqua regia</i> attack thorium readily, but +the alkalies are without action. The metal examined by the +author behaves with the reagents in question the same as did +the specimens obtained by Berzelius. The mean specific +gravity of pure thorium is about 11. Hence it would +seem that the metal obtained by Chydenius must have contained +much foreign matter. The specific gravity of pure +thoria is 10.2207 to 10.2198. The equivalent and the density +being known, we may calculate the atomic volume. If we +admit that the metal is equivalent to 4 atoms of hydrogen, +we obtain the value 21.1. This number coincides with the +atomic volumes of zirconium (21.7), cerium (21.1), lanthanum +(22.6), and didymium (21.5). This analogy is certainly not +due to chance; it rather confirms the opinion which I have +put forward in connection with my researches on the selenites, +on certain chloro-platinates and chloro-platinites, etc., +that the elements of the rare earths form a series of quadrivalent +metals.</p> + +<hr /> + +<p class="center">[AMERICAN CHEMICAL JOURNAL.]</p> + +<h2><a name="art14" id="art14"/>FRIEDRICH WÖHLER.</h2> + +<p>No one but a chemist can appreciate the full significance +of the brief message which came to us a month ago without +warning—"Wöhler is dead!" What need be added to it? +No chemist was better known or more honored than Wöhler, +and none ever deserved distinction and honor more than he. +His life was made up of a series of brilliant successes, which +not only compelled the admiration of the world at large, but +directed the thoughts of his fellow workers, and led to results +of the highest importance to science.</p> + +<p>It is impossible in a few words to give a correct account +of the work of Wöhler, and to show in what way his life and +work have been of such great value to chemistry. Could he +himself direct the preparation of this notice, the writer knows +that his advice would be, "Keep to the facts." So far as +any one phrase can characterize the teachings of Wöhler, +that one does it; and though enthusiasm prompts to eulogy, +let us rather recall the plain facts of his life, and let them, +in the main, speak for themselves.<a name="FNanchor_2_1"></a><a href="#Footnote_2_1"><sup>1</sup></a></p> + +<p>He was born in the year 1800 at Eschersheim, a village +near Frankfort-on-the-Main. From his earliest years the +study of nature appears to have been attractive to him. He +took great delight in collecting minerals and in performing +chemical and physical experiments. While still a boy, he +associated with a Dr. Buch, of Frankfort, and was aided by +this gentleman, who did what he could to encourage in the +young student his inclination toward the natural sciences. +The first paper which bears the name of Wöhler dates from +this period, and is upon the presence of selenium in the iron +pyrites from Kraslitz. In 1820 he went to the University of +Marburg to study medicine. While there he did not, however, +neglect the study of chemistry. He was at that time +particularly interested in an investigation on certain cyanogen +compounds. In 1821 he went to Heidelberg, and in 1823 +he received the degree of Doctor of Medicine. L. Gmelin +became interested in him, and it was largely due to Gmelin's +influence that Wöhler gave up his intention of practicing +medicine, and concluded to devote himself entirely to chemistry. +For further instruction in his chosen science, Wöhler +went to Stockholm to receive instruction from Berzelius, in +whose laboratory he continued to work from the fall of 1823 +until the middle of the following year. Only a few years +since, in a communication entitled "Jugenderinnerungen +eines Chemikers," he gave a fascinating account of his journey +to Stockholm and his experiences while working with +Berzelius. On his return to Germany, he was called to teach +chemistry in the recently founded municipal trade school +(Gewerbschule) at Berlin. He accepted the call, and remained +in Berlin until 1832, when he went to Cassel to live. +In a short time he was called upon to take part in the direction +of the higher trade school at Cassel. He continued to +teach and work in Cassel until 1836, when he was appointed +Professor of Chemistry in Göttingen. This office he held at +the time of his death, September 23, 1882.</p> + +<p>In 1825 Wöhler became acquainted with Liebig, and an +intimate friendship resulted, which continued until the +death of Liebig, a few years ago. Though they lived far +apart, they met during the vacations at their homes, or traveled +together. Many important investigations were conceived +by them as they talked over the problems of chemistry, +and many papers appeared under both their names, containing +the results of their joint work. Among such papers +may be mentioned: "On Cyanic Acid" (1830); "On Mellithic +Acid" (1830); "On Sulphotartaric Acid" (1831); "On +<a name="Page_5817" id="Page_5817"/> +Oil of Bitter Almonds, Benzoic Acid, and Related Compounds" +(1832); "On the Formation of Oil of Bitter Almonds +from Amygdalin" (1837); and "On Uric Acid" +(1837).</p> + +<p>Of the papers included in the above list, the two which +most attract attention are those "On the Oil of Bitter Almonds" +and "On Uric Acid." In the former it was shown +for the first time that in analogous carbon compounds there +are groups which remain unchanged, though the compounds +containing them may, in other respects, undergo a variety of +changes. This is the conception of radicals or residues as +we use it at the present day. It cannot be denied that this +conception has done very much to simplify the study of +organic compounds. The full value of the discovery was +recognized at once by Berzelius, who, in a letter to the +authors of the paper, proposed that they should call their +radical proin or orthrin (the dawn of day), for the reason +that the assumption of its existence might be likened to the +dawn of a new day in chemistry. The study of this paper +should form a part of the work of every advanced student +of chemistry. It is a model of all that is desirable in a +scientific memoir. The paper on uric acid is remarkable +for the number of interesting transformation products described +in it, and the skill displayed in devising methods +for the isolation and purification of the new compounds. +Comparatively little has been added to our knowledge of +uric acid since the appearance of the paper of Liebig and +Wöhler.</p> + +<p>It would lead too far to attempt to give a complete list of +the papers which have appeared under the name of Wöhler +alone. In 1828 he made the remarkable discovery that when +an aqueous solution of ammonium cyanate, CNONH<sub>4</sub>, is +evaporated, the salt is completely transformed into urea, +which has the same percentage composition. It would be +difficult to exaggerate the importance of this discovery. +That a substance like urea, which up to that time had only +been met with as a product of processes which take place in +the animal body, should be formed in the laboratory out of +inorganic compounds, appeared to chemists then to be little +less than a miracle. To-day such facts are among the commonest +of chemistry. The many brilliant syntheses of well-known +and valuable organic compounds which have been +made during the past twenty years are results of this discovery +of Wöhler.</p> + +<p>In 1823 he published a paper on secretion, in the urine, of +substances which are foreign to the animal organism, but +which are brought into the body. He discovered the transformation +of neutral organic salts into carbonates by the +process of assimilation.</p> + +<p>In 1832 he investigated the dimorphism of arsenious acid +and antimony oxide. In 1841 he made the discovery that +dimorphous bodies have different fusing points, according as +they are in the crystallized or amorphous condition.</p> + +<p>Among the more remarkable of his investigations in inorganic +chemistry are those on methods for the preparation of +potassium (1823); on tungsten compounds (1824); the preparation +of aluminum (1827); of glucinum and yttrium +(1828). In 1856, working with Ste. Claire Deville, he discovered +crystallized boron.</p> + +<p>Analytical methods were improved in many ways, and excellent +new methods were introduced by him. Further, he +did a great deal for the improvement of the processes of applied +chemistry.</p> + +<p>With Liebig he was associated in editing the "Annalen +der Chemie and Pharmacie" and the "Handwörterbuch der +Chemie." He wrote a remarkably useful and popular "Grundriss +der Chemie." The part relating to inorganic chemistry +appeared first in 1831, and was in use until a few years ago, +when Fittig wrote his "Grundriss" on the same plan, a +work which supplanted its prototype.</p> + +<p>The above will serve to give some idea of the great activity +of Wöhler's life, and the fruitfulness of his labors. While +thus contributing largely by his own work directly to the +growth of chemistry, he did perhaps as much in the capacity +of teacher. Many of the active chemists of the present +day have enjoyed the advantages of Wöhler's instruction, +and many can trace their success to the impulse gathered in +the laboratory at Göttingen. The hand of the old master +appears in investigations carried on to-day by his pupils.</p> + +<p>Wöhler's was not a speculative mind. He took very little +part in the many important discussions on chemical theories +which engaged the attention of such men as Dumas, Gerhardt, +Berzelius, and Liebig, during the active period of his +life. He preferred to deal with the facts as such; and no +one ever dealt with the facts of chemistry more successfully. +He had a genius for methods which has never been equaled. +The obstacles which had baffled his predecessors were surmounted +by him with ease. He was in this respect a truly +great man.</p> + +<p>Personally, Wöhler was modest and retiring. His life was +simple and unostentatious. He had a kindly disposition, +which endeared him to his students, to which fact many +American chemists who were students at Göttingen during +the time of Wöhler's activity can cordially testify. In short, +it may be said deliberately that Wöhler, as a chemist and as +a man, was a fit model for all of us and for those who will +come after us. Though he has gone, his methods live in +every laboratory. His spirit reigns in many; could it reign +in all, the chemical world would be the better for it.</p> + +<p>I.R.</p> + +<p><a name="Footnote_2_1"/><a href="#FNanchor_2_1">[1]</a></p><div class="note"><p>See Kopp's "Geschichte der Chemie," iv., 440.</p></div> + +<hr /> + +<h2><a name="art01" id="art01"/>LOUIS FAVRE, CONSTRUCTOR OF THE ST. GOTHARD TUNNEL.</h2> + +<p>It is now already a year that the locomotive has been rolling +over the St. Gothard road, crossing at a flash the distance +separating Basle from Milan, and passing rapidly from +the dark and damp defiles of German Switzerland into the +sun lit plains of Lombardy. Our neighbors uproariously +fêted the opening of this great international artery, which +they consider as their personal and exclusive work, as well +from a technical point of view as from that of the economic +result that they had proposed to attain—the creation of a +road which, in the words of Bismarck, "glorifies no other +nation." As regards the piercing of the Gothard, the initiative +does, in fact, belong by good right to the powerful +"Iron Chancellor," so we have never dreamed of robbing +Germany of the glory (and it is a true glory) of having created +the second of the great transalpine routes, that open to European +products a new gate to the Oriental world. It seems +to us, however, that in the noisy concert of acclamations +that echoed during the days of the fêtes over the inauguration +of the line, a less modest place might have been made +for those who, with invincible tenacity and rare talent, directed +the technical part of the work, and especially those +15 kilometers of colossal boring—the great St. Gothard Tunnel, +which ranks in the history of great public works side +by side with the piercing of the Frejus, and the marvelous +digging of Suez and Panama.</p> + + +<p>We recall just now the names of those who, during nearly +ten years, have contributed with entire disinterestedness to +the completion of this colossal work. Over all stands a +figure of very peculiar originality—that of M. Louis Favre, +the general contractor of the great tunnel, whose name will +remain attached to the creation of this work through the +Helvetian Alps, like that of Sommeiller to the great tunnel +of the Frejus, and that of De Lesseps to the artificial straits +that henceforward join the oceans. Having myself had the +honor of occupying the position of general secretary of the +enterprise under consideration, I have been enabled to make +a close acquaintance with the man who was so remarkable +in all respects, and who, after passing his entire life in great +public works, died like a soldier on the field of honor—in +the depths of the tunnel.</p> + +<table summary="Illustrations"> +<tr> +<td valign="top"> +<div class="figcenter" style="width: 354px;"> +<a href="./images/fig1-1.png"><img src="images/fig1-1-small.png" width="354" height="450" alt="Louis Favre" title="" /> +</a> +<span class="caption">LOUIS FAVRE.</span> +</div> +</td> +<td valign="top"> +<div class="figcenter" style="width: 268px;"> +<a href="images/fig1-2.png"> +<img src="images/fig1-2-small.png" width="268" height="450" alt="The Downfall of the Titans, Conquered by the Genius of Man" title="" /> +</a> +<span class="caption"> +THE DOWNFALL OF THE TITANS, CONQUERED BY THE GENIUS OF MAN. (Monument at +Turin to Commemorate the Tunneling of the Alps.)</span> +</div> +</td> +</tr> +</table> + +<p>I saw Favre, for the first time, in Geneva, in 1872, a few +days after he had assumed the responsibility of undertaking +the great work. He had been living since the war on his +magnificent Plongeon estate, on the right bank of the lake. +There was no need of dancing attendance in order to reach +the contractor of the greatest work that has been accomplished +up to the present time, for M. Favre was easy of access. +We had scarcely passed five minutes together than we +we were conversing as we often did later after an acquaintance +of six years. After making known to him the object +of my visit, the desire of being numbered among the <i>personnel</i> +of his enterprise, the conversation quickly took that turn + +of mirthfulness that was at the bottom of Favre's character. +"This is the first time," said he to me, laughing, "that +I ever worked with Germans, and I had not yet struck the +first blow of the pick on the Gothard when they began to +quibble about our contract of the 8th of last August. Ah! +that agreement of August 8th! How I had to change and re-change +it, later on. If this thing continues, we shall have +a pretty quarrel, considering that I do not understand a +word of the multiple interpretations of their <i>charabia</i>. I +ought to have mistrusted this. But you see I have remained +inactive during the whole of this unfortunate war. I was +not made for promenading in the paths of a garden, and I +should have died of chagrin if such inaction had had to be +prolonged. When one lives, as I have, for thirty years around +lumber yards, it is difficult to accustom one's self to the +sedentary and secluded life that I have led here for nearly +two years."</p> + +<p>As he said, with just pride, Louis Favre had, indeed, before +becoming the first contractor of public works in the +world, lived for a long time in lumber yards. The years +that so many other better instructed but less learned persons, +who were afterward to gladly accept his authority, +had given up to their studies, Favre had passed in the humble +shop of his father, a carpenter at Chêne, a small village +at a half league from Geneva. It soon becoming somewhat +irksome for him in the village, he left the paternal workbench +to start on what is called the "tour of France." He +was then eighteen years of age. Three years afterward, he +was undertaking small works. It was not long ere he was +remarked by the engineers conducting the latter, and he was +soon called to give his advice on all difficult questions. Between +times, Favre had courageously studied the principal +bases of such sciences as were to be useful to him. In the +evening, he made up at the public school what was lacking +in his early instruction; not that he hoped to make a complete +study for an engineer, but only to learn the indispensable. +He was, before all things, a practical man, who made +up for the enforced insufficiency of his technical knowledge +by a <i>coup d'œil</i> of surprising accuracy. Here it may be said +to me that the piercing of the great St. Gothard Tunnel was +accompanied by considerable loss. That is true, but it must +be recalled also that this colossal work was accomplished +amid the most insurmountable difficulties which ever presented +themselves. In spite of this, the cost of the tunnel +per running foot was also a third less than that of the great +Mont Cenis Tunnel.</p> + +<p>When Favre undertook the St. Gothard, he already reckoned +to his credit numerous victories in the domain of public +works, especially in the construction of subterranean +ones. The majority of tunnels of any length which, since +the beginning of the establishment of railways, have been +considered as works of some proportions (the Blaisy Tunnel, +for instance), were executed by him, in addition to other +open air works. So Favre reached the St. Gothard full of +hope. The battle with the colossus did not displease him, +and his courage and his confidence in the success of the +work seemed to increase in measure as the circumstances +surrounding the boring became more difficult. In the presence +of the terrible inundation of the gallery of Airolo and +the falling of aquiferous rocks, creating in the subterranean +work so desperate a situation that a large number of very experienced +engineers almost advised the abandonment of the +works, Favre remained impassive. Amid the general apprehension, +which, it may be readily comprehended, was felt in +<a name="Page_5818" id="Page_5818"/> +such a situation he made his confident and cheerful voice +heard, reviving the ardor of all, and speaking disdainfully +of "that insignificant Gothard, which would come out all +right." The <i>personnel</i> of the enterprise were not the only +ones, however, who were uneasy over the constantly occurring +difficulties in the way of the work, for the company +itself and the Swiss Federal Council made known to Favre +their fears that the execution of the work would be delayed. +He, however, calmed their fears, and exposed his projects +to them, and the seances always ended by a vote of confidence +in the future of the undertaking. Favre certainly did +not dissimulate the difficulties that he should have to conquer, +but he execrated those who were timorous and always +tried to put confidence into those who surrounded him. +But, singular phenomenon, he ended by deceiving himself +and, at certain times, it would not have been easy to prove +to him that the St. Gothard was not the most easy undertaking +in the world. Those who have lived around him know +the jokes that he sometimes made at the expense of poor +Gothard, which paid him back with interest, however, and +did not allow itself to be pierced so easy after all.</p> + +<p>Such confidence as existed in the first years, however, was +not to exist for ever. The tunnel advanced, the heading +deepened, but at the price of what troubles, and especially +of how many expenses! Day by day one could soon count +the probable deficit in the affair and the silent partners began +to get a glimpse of the loss of the eight millions of securities +that had had to be deposited with the Swiss Federal +Council. For Favre personally the failure of the enterprise +would have been ruin for his fortune was not so large as +has been stated. To fears which Favre possessed more on +account of the associates that he had engaged in the enterprise +than for himself, came to join themselves those troubles +with the Germans that he had spoken to me about on +the first day. The St. Gothard Company, whose troubles +are so celebrated, and whose inactivity lasted until the reconstruction +of the affair, was seemingly undertaking to +make Favre, who was directing the only work then in activity, +bear all the insults that it had itself had to endure. And +yet, amid these multiple cares, the contractor of the tunnel +did not allow himself to become disheartened. Constantly +at the breach he lived at his works, going from the gigantic +adit of Goschenen to the inundated one of Anolo, constantly +on the mountain, having no heed of the icy and perilous +crossing, and passing days in the torrential rain that was +flooding the tunnel. Who of us does not picture him in +mind as he reached the inn at night, with his high boots still +soaking wet, and his gray beard full of icicles to take his +accustomed seat at the table, and, between courses, to tell +some story full of mirth, some joke from the other works +whence he had come, which made us laugh immoderately, +and brought a smile to the faces of the German engineers.</p> + +<p>It is a singular coincidence that this confidence in his own +work, despite all the struggles borne, was shared likewise by +another man than Favre—by Germano Sommeiller, the creator +of the Mont Cenis Tunnel. When the work of the first +piercing of the Alps was yet in the period of attacks and +incredulity, Sommeiller wrote his brother the following letter: +"Always keep me posted my dear Leander, as to what +the laughers are saying and remember the proverb that +'he will laugh well who laughs last!' The majority of the +people, even engineers, are rubbing their hands in expectation +of the colossal fiasco that awaits us, and it is for that +that the envious keep somewhat silent. I will predict to +you that as soon as success is assured everybody will mount +to the house tops and say 'I told you so! It was an idea of +my own!' What great geniuses are going to spring from +the earth! I am in haste, so adieu, courage, energy, silence +and especially cheerfulness! And especially cheerfulness!" +Perhaps this cheerfulness of strong minds is the invincible +weapon of those who, like Sommeiller and Favre, fight +against apathy or the bad faith of their adversaries! Like +Favre however Sommeiller had not the pleasure of being +present at the consecration of his glory, for at the Mont Cenis +banquet as at the St. Gothard the place reserved for the +creator of the great work was empty.</p> + +<p>As disastrous as was the enterprise from a financial point +of view what a triumph for Favre would have been the day +on which he traversed from one end to the other that 15 kilometers +of tunnel that he had walked over step by step +since the first blow of the pick had struck the rock of the +St. Gothard! But such a satisfaction was not to be reserved +for him. Suddenly, on the 19th of July, 1879, less than +seven years after the beginning of the work, and six months +before the meeting of the adits, in the course of one of his +visits to the tunnel Favre was carried off by the rupture of +a blood vessel. A year before that epoch, I had left the enterprise, +Favre having confided to me the general supervision +over the manufacture of dynamite that he had undertaken at +Varallo Pombia for the needs of his tunnel, but my friend +M. Stockalper, engineer in chief of the Goschenen section, +who accompanied Favre on his fatal subterranean excursion, +has many a time recounted to me the sad details of his sudden +death.</p> + +<p>For months before it must be said Favre had been growing +old. The man of broad shoulders and with head covered +with thick hair in which here and there a few silver threads +showed themselves, and who was as straight as at the age of +twenty years, had begun to stoop, his hair had whitened +and his face had assumed an expression of sadness that it +was difficult for him to conceal. As powerful as it was +this character had been subjugated. The transformation +had not escaped me. Often during the days that we passed +together he complained of a dizziness that became more and +more frequent. We all saw him rapidly growing old. On +the 19th of July, 1879, he had entered the tunnel with one +of his friends, a French engineer who had come to visit the +work, accompanied by M. Stockalper. Up to the end of the +adit he had complained of nothing, but, according to his +habit, went along examining the timbers, stopping at different +points to give instructions, and making now and then a +sally at his friend, who was unused to the smell of dynamite. +In returning he began to complain of internal pains. "My +dear Stockalper," said he, "take my lamp, I will join you." +At the end of ten minutes not seeing him return, M. Stockalper +exclaimed, "Well! M. Favre, are you coming?" No +answer. The visitor and engineer retraced their steps, and +when they reached Favre he was leaning against the rocks +with his head resting upon his breast. His heart had already +ceased to beat. A train loaded with excavated rock +was passing and on this was laid the already stiff body of +him who had struggled up to his last breath to execute a +work all science and labor. A glorious end, if ever there +was one!</p> + +<p>Favre died in the full plenitude of his forces at less than +fifty four years of age, and I can say, without fear of contradiction, +that he was universally and sincerely regretted +by all those who had worked at his side. Still at the present +time when a few of us old colleagues of Goschenen, + +Airolo or Altorf meet, it is not without emotion that we +recall the old days, the joyful reunions at which he cheered +the whole table with his broad and genial laugh.—<i>Maxime +Helene, in La Nature.</i></p> + +<hr /> + +<h2><a name="art02" id="art02"/>THE NEW HARBOR OF VERA CRUZ.</h2> + +<p>Besides the enormous engineering work of rendering +navigable one of the mouths of the Mississippi Delta, and the +continuous labor of developing the more original and still +bolder project for an Isthmian ship railway, Mr. James B. +Eads has been engaged in the design of new and extensive +harbor works at Vera Cruz, which, when completed, will +secure for that city a commodious and secure port. The +accompanying plan shows the natural features of the locality, +as well as the new works. The harbor is formed by the +coast line from the Punta de la Caleta to the Punta de +Hornos, and by La Gallega reef. From the first named +point a coral reef, nearly dry at low water, extends out about +300 yards into the gulf, and a similar one of about the same +length runs out from the Punta de Hornos. Between these +is a bay 2,000 meters wide, and at its northwest end lies the +city of Vera Cruz. The bay is partly inclosed by an island +or reef—La Gallega—which, on the harbor front, has a +length of 1,200 meters. Beyond this, and to the southeast, +is another small island—the Lavendera reef. Between the +end of this reef and that projecting from the Punta de Hornos +is 320 meters wide. As will be seen from the plan the +natural harbor is exposed to the gale from the north and +northwest, while the formation affords general protection +from the northeast and southeast thanks to five large +coral reefs. Not unfrequently, however, heavy seas sweep +through the wide channels between these small islands interfering +seriously with vessels lying alongside the present +limited wharfage. Northeast, La Gallega and Gallaguilla +reefs run northward from the harbor for 3,300 meters and +these with the main coast line, form a bay exposed to the +full fury of the winds from the north, and when northern +winds prevail rough water is driven through the passage +between La Gallega and Caleta reefs with great violence, +and sets up a rapid and dangerous current into the harbor.</p> + +<div class="figcenter"> +<a href="images/fig2-1.png"> +<img src="images/fig2-1-small.png" width="341" height="450" alt="New harbor at Vera Cruz" title="" /> +</a><br /> +<span class="caption">NEW HARBOR AT VERA CRUZ.</span> +</div> + +<p>From the foregoing it will be seen that, while presenting +some advantages, the natural harbor of Vera Cruz possesses +many drawbacks and dangers which the design of Mr. Eads +will completely remove. The leading features of the works +about to be carried out are indicated on the plan. They +comprise</p> + +<p>1. The construction of a sea wall between La Gallega and +the Lavendera reefs, with an extension over the latter.</p> + +<p>2. The construction of a sea wall from Punta de la Caleta +to La Gallega. This part of the work will be begun after +the completion of the first wall to a height of at least 3 ft. +above low water.</p> + +<p>3. A dike connecting the northern ends of the first two +dikes with each other, and stretching across the southern +part of La Gallega, to prevent the seas which sometimes +break over this reef from entering the harbor. The wall +between La Gallega and Lavendera will not only cut off +the rough water during northerly gales, but will also effectually +prevent the deposition of sand in the harbor, because + +the through passage to the northwest will be stopped. +Passages closed by sluice gates will be formed through this +wall at about low water level, so that at any time the harbor +may be flushed out and stagnation prevented.</p> + +<p>4. After the construction of the inclosing walls the harbor +will be dredged out and cleared of coral to a depth of 25ft. +below low water.</p> + +<p>5. Following these works of primary importance comes +the construction of a wooden roadway from the Hornos reef +to the northwestern dike. This roadway will form the +south front of the harbor, and the excavated material will +be deposited on the space between the roadway and the +existing bottom, so as ultimately to make it a permanent +work with a masonry retaining wall fronting the harbor. +The land between the roadway and the city would also be +reclaimed to the extent of more than 740,000 square yards.</p> + +<p>6. The construction of wooden piers at right angles to the +roadway, which would be extended to run around the harbor +as trade required it, for ships to be alongside for loading +and unloading. The construction of these short piers would +be similar to those used in New York and other United +States ports, and they might afterward be replaced by +masonry if the increase in trade justified so large an expenditure.</p> + +<p>7. The erection of a lighthouse, at or near the eastern +end of the Lavendera sea wall of a second on the eastern +side of La Gallaguilla reef, and of another on the west side +of La Blanquilla reef. These houses will be furnished with +distinctive signals to enable steamers running in before +another to run with safety between La Gallaguilla and La +Blanquilla as soon as the Lavendera light is seen between +the other two.</p> + +<p>The width of deep water at the entrance between the Lavendera +and Hornos reefs will be 1,000 ft. The estimated +cost of these extensive works is ten millions of dollars, a +large sum for the Mexican Republic to expend in harbor +improvements at one port but it will doubtless be found a +profitable investment as it will tend greatly to promote +trade, and so increase indefinitely the commerce of the port.</p> + +<p>Mr. Eads' plan having been approved by the Mexican +Government the work was formally commenced on the +14th of last August. Plans were also furnished by him at +the request of the Government, for deepening the mouth of +the Panuco River upon which is located the city of Tampico, +the Gulf terminus of the Mexican central railway system.—<i>Engineering.</i></p> + +<hr /> + +<h2><a name="art03" id="art03"/>COST OF POWER TO MAKE FLOUR.</h2> + +<p>The following estimate of the cost of the power required to +manufacture a barrel of flour is taken from the <i>Miller</i>. The +calculation would hardly hold good in this country owing +to difference in cost of fuel attendance etc., but is nevertheless +of interest.</p> + +<p>"The cost of a steam motor per 20 stone (280 lb.) sack of +flour depends entirely on local circumstances. It depends +first, on the amount of power expended in the production +of a sack of flour, that is on its mode of manufacture, and +it depends, secondly, on the cost of the necessary amount of +power, that is, on the cost of fuel burned per horse power +<a name="Page_5819" id="Page_5819"/> +The average consumption of coal of first class steam engines +may be taken at 2 lb. per hour per indicated horse power.</p> + +<p>"Supposing a mill with six pairs of stones, two pairs of +porcelain roller mills, and the necessary dressing, purifying, +and wheat cleaning machinery to require a steam motor of +100 indicated horse power to drive it, then the average +consumption of fuel in this mill would be 200 lb. of coal per +hour. Such a mill working day and night will turn out +about 400 sacks of flour per week of, say, 130 hours, so that +200 × 13 = 26,000 lb. of coal would be required to manufacture +400 sacks of flour. The cost of this quantity of coal may +be taken at, say, £12 (about $58.32), and for cost of attending +engine and boiler, cost of oil, etc., another £3 (about +$14.58) per week may be added; so that, in this case, the +manufacture of 400 sacks of flour would cause an expenditure +of £15 ($72.90) for the steam motor. Therefore the cost +of the steam motor per 20-stone sack of flour may be taken +at 9d. (about 18 cents) per sack, if an improved low grinding +system is used.</p> + +<p>"In this case it is supposed that about 55 per cent. of flour +is obtained in the first run, leaving about 30 per cent. of +middlings and about 12 per cent. of bran, which is finished in +a bran duster. The middlings are purified, ground over one +pair of middling stones, then dressed through a centrifugal +and the tailings of the latter are passed over one of the porcelain +roller mills, whereas the other porcelain roller mill treats +the second quality of middlings coming from the purifier. +The products from the two porcelain roller mills are dressed +through a second centrifugal, and the whole flour is mixed +into one straight grade. Four pairs of stones are supposed +to work on wheat, one on middlings, and one pair is sharpening. +The first run is supposed to be dressed through two +long silk reels. Of course, not every steam motor has so +low a consumption of coal as two pounds per hour per horse +power; it often amounts to three, four, and five pounds per +hour. In that case, of course, the cost of steam power per +sack is much greater than 9d. per sack. A greater number +of breaks does not necessarily increase the cost of steam +power per sack of flour. Although more machines may be +employed, each of them may require less horse power; +so that the total amount of power required for manufacturing +an equal amount of flour may not be greater in the case +of gradual reduction.</p> + +<p>"As, however, the cost of maintenance may be slightly +greater in the latter case, on account of a greater number of +more elaborate machines, the cost of manufacturing a sack +of flour may be a little greater when gradual reduction is +employed, taking into account the total expenses of the mill +and interest on the capital employed.</p> + +<p>"Water motors are generally a much cheaper source of +energy than steam motors, but they are not so reliable and +constant as the latter. The very irregular supply of water +sometimes causes stoppages of the mill, and often a reserve +steam engine has to be provided in order to assist the water +motor when the quantity of water decreases during the +summer months. Wind motors were formerly extensively +used for milling purposes, but they are now gradually disappearing. +They are too irregular and unreliable, although +they utilize a very cheap motive power. It is not advantageous +to expend a large amount of capital for a mill which +often is unable to work at the very time when there are +favorable opportunities for doing profitable business. Animal +motors are too dear. They are only suitable for driving +very small mills in out of the way localities."</p> + +<hr /> + +<h2><a name="art04" id="art04"/>DRIVING GEAR MECHANISM FOR LIFT HAMMERS.</h2> + +<p>A very interesting system of driving gear for lift hammers +was applied in an apparatus exhibited at Frankfort in 1881 +by Mr. Meier of Herzen. The arrangement of the mechanism +is shown in Figs. 1 and 2. In the upper part of the hammer-frame +there is a shaft which is possessed of a continuous +rotary motion, and, with it, there is connected by a +friction coupling a drum that receives the belt from which +is suspended the hammer. In the apparatus exhibited, the +mechanism is so arranged that the hammer must always follow +the motion of the controlling lever in the same direction; +but a system may likewise be adopted such that the +hammer shall continue to operate automatically, when +and so long as a lever prepared for such purpose is lowered.</p> + +<p><i>ab</i> is the shaft having a continuous rotary motion, and +upon which are fixed the pulley, <i>c</i>, the fly-wheel, <i>d</i>, and +the friction-disk, <i>e</i>. Upon one of the extremities of the +driving shaft is fixed an elongated sleeve, formed of the +drum, <i>g</i>, and of the screw, <i>f</i>, carried by the nut, <i>h</i>. This +latter is supported in the frame in such a way that it cannot +turn, but can move easily in the direction of the axis. Such +motion may be produced by the spring, <i>i</i>, and its extent is +such that the drum, <i>g</i>, is brought in contact with the friction-disk, <i>e</i>.</p> + +<p>The hand-lever, <i>k</i>, rod, <i>l</i>, and bent lever, <i>m</i>, serve to bring +about a motion in the opposite direction, and which disengages +the drum, <i>g</i>, from the disk, <i>e</i>, and lets the hammer +fall; the drum being then able to turn freely. If the lever, <i>k</i>, +be afterward raised again, the spring, <i>i</i>, will act anew and +couple the drum with the driving-shaft, so that the hammer +will be lifted. In this rotary motion the screw, <i>f</i>, turns or +re-enters into its nut, which it displaces toward the left, +since it cannot itself move in that direction until the rectilinear + +motion be wiped out, and the power of the spring be thus +overcome. At the same moment, the screw should naturally +also make this rectilinear movement forward, that is to +say, the coupling would be disengaged, if, at the least lateral +motion toward the right, the spring, <i>i</i>, did not push the +system toward the left. There is thus produced a state of +equilibrium such that there is just enough friction between +the disk, <i>e</i>, and the drum, <i>g</i>, to keep the hammer at +rest and suspended. Through the action of an external force +which lowers the lever, K, the hammer at once falls, and the +screw issues anew from its nut and brings the parts into their +former positions.</p> + +<div class="figcenter"> +<a href="images/fig4-1.png"> +<img src="images/fig4-1-small.png" width="200" height="450" alt="MEIER'S DRIVING GEAR MECHANISM FOR LIFT HAMMERS" title="" /> +</a><br /> +<span class="caption">MEIER'S DRIVING GEAR MECHANISM FOR LIFT HAMMERS.</span> +</div> + +<hr /> + +<h2><a name="art05" id="art05"/>DE JUNKER & RUH'S MACHINE FOR CUTTING ANNULAR WHEELS.</h2> + +<p>The machine shown in Figs. 1, 2, and 3 has been devised +by Messrs. Junker & Ruh, of Carlsruhe, for cutting internally-toothed +gear-wheels. The progress of the work is such that +the wheel is pushed toward the tool by a piece, <i>n</i>, provided +with a curve guide, and that the tool is raised and separated +from the wheel after a tooth has been cut, in order to +allow the wheel to revolve one division further.</p> + +<p>The tool is placed in a support, <i>b</i>, which is fixed to the +upright, <i>d</i>, in such away that it may revolve; and this support +is connected to the frame, <i>a</i>, of the machine. A strong +flat spring, <i>f</i>, constantly presses the tool-carrier, <i>b</i>, toward +the upright, <i>d</i>, as much as the screw, <i>g</i>, will permit; and +this pressure and the tension of the belt draw the tool downward. +The screws, <i>g</i>, determine the depth of the cut, and +compensate for the differences in the diameter of the tool.</p> + +<div class="figcenter" style="width: 600px;"> +<a href="images/fig5-1.png"> +<img src="images/fig5-1-small.png" width="600" height="208" alt="Machine for Cutting Annular Wheels" title="" /> +</a> +<span class="caption">MACHINE FOR CUTTING ANNULAR WHEELS.</span> +</div> + +<p>The wheels to be cut are set by pressure into a wrought iron +ring, with which they are placed in a sleeve or support, <i>h</i>. +The connection between the two is assured by means of a +nut, <i>c</i>. The axle of the support, <i>h</i>, is held in the upright of +the carriage, <i>k</i>, which receives from a piece, <i>l</i>, placed on +the driving-shaft, <i>n</i>, a slow forward motion toward the tool, +and a rapid motion backward. The trajectory curve or +groove of special form of the piece, <i>l</i>, in which moves the conducting +roller, <i>o</i>, of the carriage, is not closed everywhere +on the two sides, in that the guides that limit it extend only + +on the part strictly necessary. This arrangement permits +of the roller being made to leave the trajectory in order that +the carriage may be drawn back to a sufficient distance from +the tool when the wheel is finished, so as to replace the latter +by another.</p> + +<p>One hollow is cut during each forward travel of the carriage; +and, when such travel is finished, a cam-disk, <i>p</i>, +placed on the shaft, <i>n</i>, lifts the tool-carrier, <i>b</i>, and thus +draws the cutting-tool out of the hollow cut by it, so that the +carriage cam can then move back without restraint. In the +interim, the sleeve, <i>h</i>, which supports the wheel, revolves one +tooth through the following arrangement: On the axis, <i>e</i>, of +this sleeve there are two ratchet-wheels, <i>r</i> and <i>s</i>, the number +of whose teeth is equal to that of the teeth to be cut in the +wheel. The wheel, <i>r</i>, produces the rotation of the sleeve, <i>h</i>, +and the wheel, <i>s</i>, keeps the shaft stationary during the operation. +The two wheels are set in motion by a lever, <i>t</i>, or by +its click, this lever being raised at the desired moment on the +free extremity of the driving shaft, <i>n</i>, by a wedge, <i>u</i>. The +short arm of the lever, <i>t</i>, engages, through its point of appropriate +shape, with the teeth of the wheel, <i>s</i>, so as to keep +this latter stationary while the tool is cutting out the interspace +between the teeth. When the lever, <i>t</i>, is raised, this +point is at first disengaged from the wheel, <i>s</i>; and the raising +of the lever being prolonged, the button, <i>i</i>, places itself +against the upper curve of the slot in the lever, <i>q</i>, and +raises that likewise. <i>q</i> is connected with the lever, <i>v</i>, which +revolves about the axis, <i>e</i>, and <i>v</i> carries the click, <i>w</i>, so that +when the lever, <i>v</i>, is raised, the wheel, <i>r</i>, turns forward by +one tooth. When the lever, <i>t</i>, is lowered, as the wedge, <i>u</i>, +turns more, its click holds the wheel, <i>s</i>, stationary. This +series of operations is repeated until the last interspace between +the teeth has been cut, when the machine stops automatically +as follows: A cam of the disk, A, which receives +from the shaft, <i>n</i>, through cone-wheels, a motion corresponding +to that of the wheels, <i>r</i> and <i>s</i>, abuts against the two-armed +lever, <i>z</i>, and this latter then disengages the rod, <i>y</i>, so +that the weight, G, can move the fork, B, in such a way that +the belt shall pass from the fast to the loose pulley.</p> + +<p>Motion is communicated to the machine as a whole by the +shaft, C, which is provided with a fast and loose pulley. As +shown in the engraving, the pulley, D, moves the tool, and +the pulley, E, causes the revolution of the shaft, <i>n</i>, through +a helicoidal gearing, F.</p> + +<p>The construction of the tool carrier is represented in detail +in Fig. 3. The cutting tool, F, rests on a sleeve forming +part of the pulley, <i>r</i><sub>1</sub>, against which it is pressed by a +nut, while its position is fixed by a key. The axle, <i>s</i><sub>1</sub>, of the +tool is held in two boxes, in which it is fixed by screws. In +order that the tool may be placed exactly in the axis of the +wheel to be toothed, and that also the play produced by +lateral wear of the pulley, <i>r</i><sub>1</sub>, may be compensated for, two +screws, <i>r</i><sub>2</sub>, are arranged on the sides. All rotation of the +shaft, <i>s</i><sub>1</sub>, is prevented by a screw, <i>o</i>, which traverses the cast +iron stirrup, C, and the steel axle box.</p> + +<hr /> + +<h2><a name="art06" id="art06"/>RECENT HYDRAULIC EXPERIMENTS.</h2> + +<p>At a late meeting of the Institution of Civil Engineers, the +paper read was on "Recent Hydraulic Experiments," by +Major Allan Cunningham, R.E.</p> + +<p>This paper was mainly a general account of some extensive +experiments on the flow of water in the Ganges Canal, +lasting over four years—1874-79. Their principal object +was to find a good mode of discharge measurements for large +canals, and to test existing formulæ. There are about 50,000 +velocity, and 600 surface-slope measurements, besides many +special experiments. The Ganges Canal, from its great size, +from the variety of its branches abounding in long straight +reaches, and from the power of control over the water in it, +was eminently suited for such experiments. An important +feature was the great range of conditions, and, therefore, also +of results obtained. Thus the chief work was done at thirteen +sites in brickwork and in earth, some being rectangular +and others trapezoidal, and varying from 193 ft. to 13 ft. in +breadth, and from 11 ft. to 7 in. in depth, with surface-slopes +from 480 to 24 per million, velocities from 7.7 ft. to 0.6 ft. +per second, and discharges from 7,364 to 114 cubic feet per +second. For all systematic velocity measurements, floats +were exclusively used, viz., surface floats, double floats, and +loaded rods. Their advantages and disadvantages had been +fully discussed in the detailed treatise "Roorkee Hydraulic +Experiments"—1881. They measured only "forward velocity," +the practically useful part of the actual velocity. The +motion of water, even when tranquil to the eye, was found +to be technically "unsteady;" it was inferred that there is +no definite velocity at any point, and that the velocity varies +everywhere largely, both in direction and in magnitude. +The average of, say, fifty forward velocity measurements at +any one point was pretty constant, so that there must be probably +average steady motion. Hence average forward velocity +measurements would be the only ones of much practical use. +To obtain these would be tedious and costly, and special +arrangements would be required to obviate the effects of a +change in the state of water, which often occurred in a long +experiment, as when velocities at many points were wanted.</p> + +<p>As to surface-slope its measurement—from nearly 600 +trials—was found to be such a delicate operation that the +result would be of doubtful utility. This would affect the application +of all formulas into which it entered. The water surface +was ascertained, on the average of its oscillations, to be +sensibly level across, not convex, as supposed by some writers. +<a name="Page_5820" id="Page_5820"/> +There were 565 sets of vertical velocity measurements combined +into forty-six series. The forty-six average curves +were all very flat and convex down stream—except near an +irregular bank—and were approximately parabolas with +horizontal axes; the data determined the parameters only +very roughly; the maximum velocity line was usually below +the service, and sank in a rectangular channel, from the +center outward down to about mid-depth near the banks. +Its depression seemed not to depend on the depth, slope, +velocity, or wind; probably the air itself, being a continuous +source of surface retardation, would permanently depress +the maximum velocity, while wind failed to effect this, owing +to its short duration. On any vertical the mid-depth +velocity was greater than the mean, and the bed velocity +was the least. The details showed that the mid-depth +velocity was nearly as variable from instant to instant as +any other, instead of being nearly constant, as suggested by +the Mississippi experimenters.</p> + +<p>The measurement of the mean velocity past a vertical was +thought to be of fundamental importance. Loaded rods +seemed by far the best for both accuracy and convenience in +depths under 15 ft. They should be immersed only 0.94 of +the full depth. The chief objection to their use, that—from +not dipping into the slack water near the bed—they moved +too quickly, was thus for the first time removed. A double +float with two similar sub-floats at depths of 0.211 and 0.789 of +the full depth would also give this mean with more accuracy +and convenience than any instrument of its class; this instrument +is new. Measurement of the velocity at five eighths +depth would also afford a fair approximation.</p> + +<p>One hundred and fourteen average transverse velocity +curves were prepared from 714 separate curves. These +average curves were all very flat, and were convex down +stream—over a level or concave bed—and nearly symmetric +in a symmetric section. The velocity was greatest near the +center, or deepest channel, decreased very slowly at first toward +both banks, more rapidly with approach to the banks +or with shallowing of the depth, very rapidly close to the +banks, and was very small at the edges, possibly zero. The +figure of the curve was found to be determined by the figure +of the bed, a convexity in the bed producing a concavity +in the curve and <i>vice versa</i>, and more markedly in shallow +than in deep water. Curves on the same transversal, +at the same site, and with similar conditions, but differing +in general velocity, were nearly parallel projections. At +the edges there was a strong transverse surface flow from the +edge toward mid-channel, decreasing rapidly with distance +from the edge. The discussion showed that it was almost +hopeless to seek the geometric figure of the curves from +mere experiment.</p> + +<p>Five hundred and eighty-one cubic discharges were measured +under very varied conditions. The process adopted +contained three steps: (1) Sounding along about fifteen float +courses, scattered across the site in eight cross sections; time, +say four hours. (2) Measurement of the mean velocities +through the full depths in those float courses, each thrice repeated; +time, say four hours. (3) Computation, say two +hours. This process was direct and wholly experimental; +each step was done in a time which gave some chance of a +constant state of water. From an extended comparison of +all results under similar conditions, it appeared that the +above process yielded, under favorable circumstances, results +not likely to differ more than 5 per cent. The sequel showed +that in a channel with variable regimen, a discharge table +for a given site must be of at least double entry, as dependent +on the local gauge-reading, and on the velocity or surface-slope.</p> + +<p>Special attention was paid to rapid approximations to +mean sectional velocity. The mean velocity past the central +vertical, the central surface velocity, and Chézy's quasi-velocity—i.e.,</p> + +<p class="center">100 × √<span class="overline">( R × S )</span></p> + +<p>where R=the hydraulic mean depth, +and S=surface slope—were tried in detail; thus 100, 76, +and 83 average values thereof respectively were taken from +581, 313, and 363 detail values. The ratios of these three +velocities to the mean velocity were taken out, and compared +in detail with Bazin's and Cutter's coefficients. Other +formulæ were contrasted also in slight detail. Kutter's alone +seemed to be of general applicability; when the surface +slope measurement is good, and the rugosity coefficient +known for the site—both doubtful matters—it would probably +give results within 7½ per cent. of error. Improvement +in formulæ could at present be obtained only by increased +complexity, and the tentative research would be excessively +laborious. Now the first two ratios varied far less +than the third; thus their use would probably involve less +error than the third, or approximation would be more likely +from direct velocity measurement than from any use of +surface slope. The connection between velocities was probably +a closer one than between velocity and slope; the former +being perhaps only a geometric, and the latter a physical +one. The mean velocity past the central vertical was recommended +for use, as not being affected by wind; the reduction +coefficient could at present only be found by special experiment +for each site. Three current meters were tried for +some time with a special lift, contrived to grip the meter +firmly parallel to the current axis, so as to register only forward +velocity, and with a nearly rigid gearing wire. No +useful general results were obtained. Ninety specimens of +silt were collected, but no connection could be traced between +silt and velocity; it seemed that the silt at any point +varied greatly from instant to instant, and that the quantity +depended not on the mean velocity, but probably on the silt +in the supply water. Forty measurements of the evaporation +from the canal surface were made in a floating pan, +during twenty five months. The average daily evaporation +was only about 1/10 in. The smallness of this result seemed +to be due to the coldness of the water—only 63 deg. in May, +with 165 deg. in the sun and 105 deg. in shade. Lastly, it +must suffice to say that great care was taken to insure accuracy +in both fieldwork and computation.</p> + +<hr /> + +<h2><a name="art07" id="art07"/>THE GERM.</h2> + +<h3><span class="smcap">By Arthur Atkins.</span></h3> + +<p>There seems to have sprung up within a few mouths +a tendency to revive the discussion on that hackneyed question, +"Shall the germ be retained in the flour?" This +question has been more than once answered in the negative +by both scientific and practical men, but recently certain +prominent persons have come to the conclusion that +every one has been wrong on this point, and the miller should +by all means retain the germ. Now the nutritive value of +the germ cannot be disputed, but there are two circumstances +which condemn it us an ingredient of flour. The +first is that the albuminoids which it contains are largely +soluble, and this means that good light bread from germy flour +is impossible. I have not time to go into a detailed explanation +of the chemical reasons for this, but they may be found in + +a series of articles which appeared in <i>The Milling World</i> about +a year ago. In the next place, the oil contained in the germ +not only discolors the flour, but seriously interferes with its +keeping qualities. Now color is only a matter of taste, and +if that were the only objection to the germ, it might be admitted, +but we certainly do not want anything in our flour +to interfere with making light, sweet bread, and will render +it more liable to spoil. If our scientists can discover some +method of obviating these objections, it will then be time +enough to talk about retaining the germ. Meanwhile millers +know that germy flour is low priced flour, and they are not +very likely to reduce their profits by retaining the germ.—<i>Milling World.</i></p> + +<hr /> + + +<h2><a name="art08" id="art08"/>WHEAT TESTS.</h2> + +<p>There was considerable complaint last season, on the +part of wheat raisers in sections tributary to Minneapolis, +on account of the rigid standard of grading adopted by the +millers of that city. It was asserted that the differentiation of +prices between the grades was unjustly great and out of proportion +to the actual difference of value. In order to ascertain +whether this was the case or not, the Farmers' Association +of Blue Earth County, Minn., decided to have samples of each +grade analyzed by a competent chemist in order to determine +their relative value. Accordingly specimens were secured, +certified to by the agent of the Millers' Association of Minneapolis, +and sent to the University of Minnesota for analysis. +The analysis was conducted by Prof. Wm. A. Noyes, Ph.D., +an experienced chemist, who has recently reported as follows:</p> + +<p>"The analyses of wheat given below were undertaken for +the purpose of determining whether the millers' grades of +wheat correspond to an actual difference in the chemical +character of the wheat. For this purpose samples of wheat +were secured, which were inspected and certified to by M. +W. Trexa on April 13th of this year. The inspection cards +contained no statement except the grade of the wheat and +the weight per bushel, but the samples were all of Fife, for +the purpose of a better comparison. The analyses of the +wheat were made during October in this laboratory. In +each case the wheat was carefully separated from any foreign +substances before analysis. The results of analysis +were as follows:</p> + +<div class="center"> +<table summary="Wheat Analyses"> +<tr> +<td> </td> +<td>Grade No. 1</td> +<td>Grade No. 2</td> +<td>Grade No. 3</td> +</tr> +<tr> +<td align="left">Weight per bushel</td> +<td align="right">59 lb.</td> +<td align="right">56½ lb.</td> +<td align="right">55 lb.</td> +</tr> +<tr> +<td align="left">Grains to weigh 10 grains</td> +<td align="right">366 Per ct.</td> +<td align="right">474 Per ct.</td> +<td align="right">491 Per ct.</td> +</tr> +<tr> +<td align="left">Foreign matter (seeds, etc.)</td> +<td align="right">0.41</td> +<td align="right">0.20</td> +<td align="right">1.57</td> +</tr> +<tr> +<td align="left">Nitrogen</td> +<td align="right">2.09</td> +<td align="right">2.08</td> +<td align="right">2.17</td> +</tr> +<tr> +<td align="left">Phosphorus</td> +<td align="right">0.35</td> +<td align="right">0.46</td> +<td align="right">0.46</td> +</tr> +<tr> +<td align="left">Water</td> +<td align="right">12.34</td> +<td align="right">11.31</td> +<td align="right">11.85</td> +</tr> +<tr> +<td align="left">Ash</td> +<td align="right">1.59</td> +<td align="right">1.92</td> +<td align="right">1.97</td> +</tr> +<tr> +<td align="left">Albuminoids (nitrogen multiplied by 6¼)</td> +<td align="right">13.06</td> +<td align="right">13.00</td> +<td align="right">13.56</td> +</tr> +<tr> +<td align="left">Cellulose</td> +<td align="right">2.03</td> +<td align="right">2.37</td> +<td align="right">2.50</td> +</tr> +<tr> +<td align="left">Starch, sugar, fat, etc.</td> +<td align="right">70.98</td> +<td align="right">71.40</td> +<td align="right">70.12</td> +</tr> +</table> +</div> + +<p>"The analyses require but little comment. The only substances +in which there is evident connection between the +results of analysis and the grades of wheat are the cellulose, +ash, and phosphorus. As regards the last substance, grades +two and three seem to have the greatest food value. But +it seems quite probable from the results that greater difference +would be found between different varieties of wheat +of the same kind than is shown here between different +grades of the same variety of wheat. However, it does not +necessarily follow from this that the different grades of wheat +are of nearly equal value to the miller for the purpose of making +flour. That is a question which can be best answered by determining +accurately the amount and character of the flour +which can be made from each grade of wheat. If possible, +the investigation will be continued in that direction."</p> + +<p>As Prof. Noyes justly remarks, the value of the different +grades of wheat can best be determined by a comparison of +the results of reducing them to flour, but an intelligent +study of the table given above would of itself be sufficient +to indicate the justness of the grading. In the first place, +even were the percentages of the different components exactly +the same in each grade, still the difference in weight +would of itself be sufficient to justify a marked difference in +price. This requires no proof, for, other things being equal, +fifty-nine pounds is worth more than fifty-five pounds. +Again, the figures show that No. 3 contained nearly four +times as much foreign matter as No. 1. Millers certainly +should not be expected to pay for foreign seeds or other substances +valueless for their purpose, at the price of wheat. +Finally, if the analysis proves anything, it proves that the +lower grades contain a decidedly larger percentage of components +which it is generally agreed, whether directly or the +reverse, ought not to be incorporated with the flour, and +are, therefore, of comparatively little value to the miller. +This is shown by the relative amounts of cellulose, ash, and +phosphorus present. Cellulose, as every one knows, is the +woody, indigestible substance which is found in the bran, +and the greater the amount of cellulose, the heavier will be +the bran in proportion to the flour producing elements. +According to the figures presented, No. 3 contained nearly +one-quarter more cellulose than No. 1, while the amount in +No. 2 was slightly less than in No. 3. The ash, too, which +represents the mineral constituents of the wheat, is directly +dependent upon the quantity of bran. Here, too, the lowest +grade is shown to yield about one-quarter more than the +highest. The larger percentage of phosphorus in the lower +grades is suggested by the analyst to indicate their greater +food value in this respect. So it would, were we in the habit +of boiling our wheat and heating it whole, or of using +"whole wheat meal." But, fortunately or unfortunately, +the bread reformers have not yet succeeded in inoculating +any considerable portion of the community with their doctrines, +and hence the actual food value of any sample +of wheat must be ascertained, not directly from the +composition of the wheat, but from the composition of the +flour made therefrom. Now, as already stated, phosphorus, +like the other mineral components, is found almost entirely +in the bran. Its presence in greater quantity, therefore, +simply adds to the testimony that a larger proportion of the +low grade wheat must be rejected than of the higher grade. +It should be evident to the complaining farmers that the +millers were in the right of the question, on this occasion at +least.</p> + +<p>It is expected that further analysis will be made, this time +of the flour made from the different grades of wheat. If +these investigations be properly conducted, we have no +doubt that they will simply confirm the evidence of the +wheat tests. A chemical analysis alone, however, will not +be sufficient. The quantity of flour obtained from a given +amount of wheat must also be ascertained and its quality + +further tested by means best known to millers, as regards +"doughing-up," keeping qualities, color, etc. And then the +result can be no less than to show what millers already knew—that +the best quality of flour, commanding the top prices in +the market, cannot be obtained from an inferior quality of +wheat.—<i>Milling World.</i></p> + +<hr /> + +<h2><a name="art15" id="art15"/>APPARATUS FOR PRINTING BY THE BLUE PROCESS.<a name="FNanchor_3_1"></a><a href="#Footnote_3_1"><sup>1</sup></a></h2> + +<h3><span class="smcap">By Channing Whitaker.</span></h3> + +<p>The blue process is well known to the members of the +society, and I need not take time to describe it; but with the +ordinary blue process printing frame the results are sometimes +unsatisfactory, and now that the process has come to +be so commonly used I have thought that an account of an +inexpensive but efficient printing frame would be of interest. +The essential parts of the apparatus are its frame, its glass, +its pad or cushion, its clamps, and the mechanism by which +the surface of the glass can easily be made to take a position +that is square with the direction of the sun's rays.</p> + +<p><i>The Blue Process Printing Frame in Common Use.—Its Defects.</i>—The +pad of the apparatus in common use consists of +several thicknesses of blanketing stretched upon a back +board. The sensitized paper and the negative are placed +between the pad and the plate glass, and the whole is +squeezed together by pressure applied at the periphery of +the glass and of the back-board. Both the glass and the +back-board spring under the pressure, and it results that the +sensitized paper is not so severely pressed against the negative +near the center of the glass as it is near the edges. If +at any point the sensitized paper is not pressed hard up +against the negative, a bluish tinge will appear where a +white line or surface was expected. With an efficient +printing frame and suitable negatives, these blue lines will +never appear, and it was to prevent the production of defective +work that I undertook to improve the pad of the printing +frame.</p> + +<p><i>The Printing Frame Used in Ordinary Photography.</i>—Very +naturally, I first examined the printing frame used in ordinary +photography. This frame is extremely simple, and is very +well adapted to its use. It is, undoubtedly, the best frame for +blue process printing, when the area of the glass is not too +large. The glass is set in an ordinary wooden frame, while +the back-board is stiff and divided into two parts. A flat, +bow-shaped spring is attached by a pivot to the center of +each half of the back-board. The two halves of the back-board +are hinged together by ordinary butts. Four lugs are +fastened to the back of the frame, and, when the back-board +is placed in position, the springs may be swung around, +parallel to the line of the hinges, and pressed under the lugs, +so that the back of the back-board is pressed most severely +at the center of each half, while the glass is prevented from +springing away from the back-board by the resistance of the +frame at its edges. Unless the frame is remarkably stiff, it +will resist the springing of the glass more perfectly in the +neighborhood of the lugs than elsewhere. It will now be +seen that, on account of the manner in which the pressure +is applied, the back-board tends to become convex toward +the glass, while the adjacent surface of the glass tends to become +concave toward the back-board; and that with such a +frame, the pressure upon all parts of the sensitized paper is +more nearly uniform than when the pressure is applied in +the manner before described. With a small frame of this +description, a piece of ordinary cotton flannel is used between +the back-board and the sensitized paper, and, with +larger sizes, one or more thicknesses of elastic woolen blanket +are substituted for the cotton flannel. There is an advantage +in having a hinged back-board like that which has been +described, because, when the operator thinks that the exposure +to sunlight has been sufficiently prolonged, he can turn +down either half of the back and examine the sensitized +paper, to see if the process has been carried far enough. If +it has not, the back-board can be replaced, and the exposure +continued, without any displacement of the sensitized +paper with respect to the negative. This is an important advantage.</p> + +<p><i>An Efficient Blue Process Frame, for Printing from Large +Negatives, or for Printing Simultaneously from many Small +Ones.</i>—In order to be efficient, such a frame must be capable +of keeping the sensitized paper <i>everywhere tightly pressed +against the negative</i>. Again, such a frame, being large, is +necessarily somewhat heavy. It should be so mounted that +it can be handled with ease; and, in order that it may print +quickly, it should be so arranged that it can be turned +without delay, at any time, into a position that is square +with the direction of the sun's rays.</p> + +<p>Undoubtedly, if a sufficiently thick plate of glass should +be used, the ordinary photographic printing frames would +answer the purpose, whatever the size, but very thick plate +glass is both heavy and expensive. Commercial plate glass +varies in thickness from one-fourth to three eighths of an +inch, and the thicker plates are rather rare. A large plate +of it is easily broken by a slight uniformly distributed pressure. +But the pressure that is required for the blue process +printing, although slight, is much greater than is used in +the ordinary photographic process. For the sensitized +paper that is used in the blue process printing is, comparatively, +very thick and stiff, and it may cockle more or less, +while the paper that is used in ordinary photography is thin +and does not cockle. Now, it is easy to see that a pressure +severe enough to flatten all cockles must be had at every part +of the sensitized paper, and that, if the comparatively thin, +inexpensive, light weight, commercial plate glass is to be +used, it is desirable to have the pressure <i>nowhere much greater +than is needed for that purpose</i>, lest the fragile glass should +be fractured by it. In each of my large frames I use the +commercial plate glass; instead of the cushion of cotton flannel, +or of flannel, I use a cushion filled with air of sufficiently +high pressure to flatten all cockles, and to press all parts +of the sensitized paper closely against the negative; and instead +of the hinged back-board I use a back-board made in +one piece and clamped to the frame of the glass at its edges. +Connected with the cushion is a pressure gauge, and a tube +with a cock, for charging the cushion with air from the +lungs. Experience shows what pressure is necessary with +any given paper, and the gauge enables one to know that the +pressure is neither deficient nor in excess of that which is +safe for the glass.</p> + +<div class="figcenter"> +<a href="images/fig15-1.png"> +<img src="images/fig15-1-small.png" width="228" height="300" alt="Plan. Cotton Flannel Removed" title="" /> +</a><br /> +<span class="caption">PLAN. COTTON FLANNEL REMOVED.<br /> SECTION AT CO.</span> +</div> + +<p><i>The Construction of the Air-Cushion.</i>—The expense of such +an air-cushion seemed at first likely to prevent its being used; +but a method of construction suggested itself, the expense +of which proved to be very slight. The wooden back-board, +as constructed, is made in one piece containing no wide +cracks. It has laid upon it some thick brown Manila paper, +the upper surface of which has been previously shellacked +to make it entirely air-tight. Upon this shellacked surface +<a name="Page_5821" id="Page_5821"/> +is laid a single thickness of thin paper of any kind; even +newspaper will answer. Its object is simply to prevent the +sheet rubber, which forms the top of the air-cushion, from +sticking to the shellacked paper. The heat of the sun is +often sufficient to bring the shellac to a sticky state. It +would probably answer as well to shellac the under side of +the paper, and to use but one sheet, but I have not tried this +plan. Around the periphery of the pad, there is laid a piece +of rubber gasket about one and a half inches wide, and about +one-eighth of an inch thick. In order that the gasket may +not be too expensive, it is cut from two strips about three +inches wide. One of them is as long as the outside length +of the frame, and the other is as long as the outside width +of the frame. Each of these strips is cut into two L-shaped +pieces, an inch and a half in width, with the shorter leg of +each L three inches long. When the four pieces are put +together a scarf joint is made near each corner, having an +inch and one-half lap. It is somewhat difficult to cut such +a scarf joint as perfectly as one would wish, and it is best +to use rubber cement at the joints. Over the gasket is laid +a sheet of the thinnest grade of what is called pure rubber or +elastic gum. Above this, and over the gasket, is placed a +single thickness of cotton cloth, of the same dimensions as +the gasket, and yet above this are strips of ordinary strap +iron, an inch and a half wide and nearly one eighth of an +inch thick. These strips are filed square at the ends and +butt against each other at right angles. As the edges of the +strips are slightly rounded, they are filed away sufficiently +to form good joints wherever the others butt against them. +The whole combination is bound together by ordinary stove +bolts, one quarter of an inch in diameter, placed near the +center of the width of the iron strips, and at a distance apart +of about two and one-half inches. Their heads are countersunk +into the strap iron. In making the holes for the stove +bolts through the thin rubber, care should be taken to make +them sufficiently large to enable the bolt to pass through +without touching the rubber, otherwise the rubber may cling +to the bolts, and if they are turned in their holes the rubber +may be torn near the bolts and made to leak. A rough +washer, under each nut, prevents it from cutting into the +back-board. For the purpose of introducing air to, or removing +air from, the pad, a three-eighths of an inch lock +nut nipple is introduced through the back-board, the shellacked +paper, and its thin paper covering. Without the +back-board a T connects with the nipple. One of its +branches leads, by a rubber tube, to the pressure gauge, +which is a U-tube of glass containing mercury. The other +branch has upon it an ordinary plug cock, and, beyond this, +a rubber tube terminating in a glass mouth-piece. When it +is desired to inflate the air-cushion, it is only necessary to +blow into the mouth-piece. A pressure of one inch of mercury +is sufficient for any work that I have yet undertaken. +With particularly good paper, a lower pressure is sufficient. +Upon the top of the pad is laid a piece of common cotton +flannel with the nap outward, and with its edges tacked +along the under edge of the back-board. The cotton flannel +is not drawn tight across the top of the pad. The reason for +employing a cotton flannel covering is this: When the sheet +rubber has been exposed for a few days to the strong sunlight, +it loses its strength and becomes worthless. The cotton +flannel is a protection against the destruction of the rubber +by the sunlight. I first observed this destruction while experimenting +with a cheap and convenient form of gauge. I +used, as an inexpensive gauge, an ordinary toy balloon, and +I could tell, with sufficient accuracy, how much pressure I +had applied, by the swelling of the balloon. This balloon +ruptured from some unknown cause, and I made a substitute +for it out of a round sheet of thin flat rubber, gathered all +around the circumference. I made holes about one-quarter +of an inch apart, and passing a string in and out drew it +tight upon the outside of a piece of three eighths of an inch +pipe, I then wound a string tightly over the rubber, on the +pipe, and found the whole to be air-tight. This served me +for some time, but one day, on applying the pressure, I +found a hole in the balloon which looked as if it had been cut +with a very sharp knife. That it had been so cut was not +to be imagined, and on further examination I found that +the fracture had occured at a line which separated a surface +in the strong sunlight from a surface in the shade, at +a fold in the rubber. I saw that all of the rubber which had +been continuously exposed to the intense sunlight had +changed color and had become whiter than before, and +that that portion of the balloon had lost its strength. I +then returned to the use of the mercury gauge, and took the +precaution to cover my pad with cotton flannel, as a protection +from the light and from other sources of destruction. +This pad is upon the roof of the Institute; and is exposed to +all weathers. As a protection from the rain and the snow, +the whole is covered again with a rubber blanket. It has +withstood the exposure perfectly well for a year, without + +injury. The gauge, made from flat rubber, is altogether so +cheap and so convenient that I am now experimenting +with one of this description having a black cloth covering +upon the outside. The balloon is of spherical shape, the +black cloth covering is of cylindrical shape, and I hope +that this device will serve every necessary purpose. A sectional +view of the air-cushion is offered as a part of this communication.</p> + +<p><i>The Frame, which Contains the Plate Glass</i>, is made of +thick board or plank, with the broad side of the board at +right angles to the surface of the glass. A rabbet is made +for the reception of the glass, and four strips of strap iron, +overlapping both the glass, and the wood, and screwed to +the wood, keep the glass in position. Strips of rubber are +interposed between the glass and the wood and between the +glass and the iron. The frame is hinged to the back-board +by separable hinges, so that the glass can be unhinged from +the pad without removing the screws. Hooks, such as are +used for foundry flasks, connect the frame with the pad +upon the opposite side. A frame made in this manner is +very stiff and springs but little, and its depth serves an excellent +purpose. The air-cushion and the frame are so +mounted that they can be easily turned to make the surface +of the glass square with the direction of the sun's rays. It +is necessary to have a tell tale connected with the apparatus, +which will show when the surface of the glass has been thus +adjusted. The shadow of the deep frame is an inexpensive +tell-tale, and enables the operator to know when the adjustment +is right. I have now described, in detail, the construction +of the air-cushion with its back-board, as well as that +of the frame which holds the plate glass, and I think it will +be evident that the first cost of the materials of which they +are made is comparatively little, and that the workmanship +required to produce it is reduced to a minimum. It will +also, I think, be evident that a uniform pressure, of any desired +intensity, can be had all over the surface of the sensitized +paper for the purpose of securing perfect contact between +it and the negative. The blue copies that are taken +with this apparatus are entirely free from blue lines when the +negatives, chemicals, and paper are good.</p> + +<p><i>The Mechanism for Adjusting the Surface of the Glass, until +it shall be Perpendicular to the Direction of the Sun's Rays.</i>—I +have found many uses for the blue copying process in connection +with the work of instruction at the Massachusetts +Institute of Technology. Notes printed by it are far better +and less costly than those printed by papyrograph. I will +not detain you now with an account of the uses that I have +made of it. I will merely say that more than a year ago I +found that my frame, which has a glass 3 feet x 4 feet, was +wholly inadequate to the work in hand, and I tried to increase +the production from it by diminishing the time of +printing. The glass of this frame was horizontal, except +when one of its ends was tilted off from the slides which +guided it when pushed out of the window; and I knew that +it took three or four times as long to print when the sun was +low as it did when the sun was near the meridian. I made +plans for mounting this frame upon a single axis, about +which it could be turned after it had been pushed through +the window, but I saw that no movement about a +single axis would give a satisfactory adjustment for all times +of the year, and I considered what arrangement of two axes +would permit a rapid and perfect adjustment, at all times, +with the least trouble to the operator. It was evident that +when the sun was in the equatorial plane, the surface +of the glass should contain a line which was parallel to the +axis of the earth; and further, that if such a glass was firmly +attached to an axis which was parallel to that of the earth, +it would fulfill the desired purpose. For the glass, being +once in adjustment, is only thrown out of position by the +rotation of the earth, and if the glass is rotated sufficiently +about its own axis, in a direction opposite to that of the +earth, it will retain its adjustment. In order to have the +adjustment equally good when the sun was either north or +south of the equatorial plane, it was sufficient to mount a +secondary axis upon the primary one and at right angles to +it. About this the glass could be turned through an angle of +23½°, either way, from the position which it should have +when the sun was in the equatorial plane.</p> + +<div class="figcenter"> +<a href="images/fig15-2.png"> +<img src="images/fig15-2-small.png" width="263" height="300" alt="Blue Process Printing Apparatus" title="" /> +</a><br /><span class="caption">BLUE PROCESS PRINTING APPARATUS.</span> +</div> + +<p><i>The Construction of the Adjusting Mechanism.</i>—I desired to +have the mechanism as compact and inexpensive as possible, +and to have the frame well balanced about the primary axis, +in every position. I also desired to have a rotation of nearly +180° about the principal axis. The plan adopted will be most +easily understood by referring to the drawing which illustrates +it. The axes are composed chiefly of wood. They +are built up from strips which are 3 inches x 7/8 inch, and +from small pieces of 2 inch plank. They are stiffly braced. +A pair of ordinary hinges permit the secondary rotation to +occur, while a pair of cast iron dowel pins with their sockets, +such as are used in foundry flasks, serve as pivots during the +primary rotation.</p> + +<p><i>The Adjustments.</i>—The adjustment about the secondary +axis does not need to be made more frequently than once a +week, or once a fortnight. In order to prevent rotation + +about this axis when in adjustment, two cords lead from +points which are beneath the back board, and as far removed +from the secondary axis as is convenient. Each cord +passes forward and backward through four parallel holes in +a wooden block which is attached to the primary axis. The +cords can be easily slipped in the holes by pulling their +loops, but the friction is so great that they cannot be slipped +by pulling at either end. It takes about twice as long to +make the adjustment as would be necessary if a more expensive +device had been used; but this device is at once so cheap, +so secure, and has so seldom to be used, that it was thought +to be best adapted for the purpose. To prevent rotation +from occurring about the primary axis when it is not desired, +a bar parallel to the secondary axis is attached by its middle +point to the primary axis near one end. A cord passes from +either end of this bar through cam shaped clamps, which +were originally designed for clamping the cords of curtains +with spring fixtures. These clamps are cheap. They are +easily and quickly adjusted, and are very secure.</p> + +<p>The whole apparatus can be located upon the roof of a +building, or, if convenient, it can be mounted upon slides, +and pushed through an open window when it is to be exposed +to the light. If it is to be used upon a roof, a small +hut, or shelter of some sort, near by is a great convenience +to the operator, particularly in winter.</p> + +<p><i>An Inexpensive Drying Case for Use in Coating the Paper.</i>—When +the apparatus is in continuous use, time may be saved +by having a convenient arrangement for drying the sheets +that have been coated with the sensitizing liquid. I have +made an inexpensive drying case which serves the purpose +very well. It consists simply of a light-tight rectangular case +of drawers. There are twenty-five drawers in all. They +are constructed in an inexpensive manner, and are the only +parts of the case that are worth describing. They are very +shallow, being but 1-7/8 inches deep, and as it appeared that +the principal expense would be for the materials of which +the bottoms of the drawers should be composed, it was decided +to make the bottoms of cotton cloth. This cloth is +stretched upon a frame, the dimensions of which are greater +than that of the paper to be dried. The stock of which the +frame is made is pine, 1¼ inches wide, and three-eighths of an +inch thick. The corners are simply mitered together and +attached to each other by means of the wire staples that are +commonly used for fastening together pages of manuscript, +and which are called "novelty staples." Eight staples are +used at each miter, four above and four below the joint. +Two of the staples, at the top and near the ends of the joint, +are set square across it, and two others, at the top and near +the middle of the joint, are placed diagonally across it. The +staples at the bottom are similarly placed. The joint is quite +firm and strong, and is likely to hold for an indefinite period +with fair usage. The cloth, stretched upon the frame, is +fastened to it by means of similar staples. A dark colored +cloth not transparent to light is to be preferred. A strip of +pine, 1-13/16 inches wide, and three eighths of an inch thick, +forms the vertical front of the drawer, and prevents the admission +of much light from the front while the sheet is drying. +Two triangular knee pieces, three-quarters of an inch +thick, serve to connect the front board with the frame, and +four small screws with a few brads are used in attaching +them. The lower edge of the front board drops one-quarter +of an inch below the bottom of the drawer. My case stands in +a poorly lighted room, and paper dried in this case and removed +to a portfolio as soon as it is dry does not seem to be +injured by the light that reaches it. With the case in a well +lighted room, I should prefer to have outer doors to the case, +made of ordinary board six or eight inches wide, hinged to +one end, and arranged to swing horizontally across the front +of the case. These would more completely prevent the admission +of light. The opening of any one of the doors would +allow three or four of the drawers to be filled, while the +rest of the case would be comparatively dark at the same +time.<a name="FNanchor_3_2"></a><a href="#Footnote_3_2"><sup>2</sup></a></p> + +<p><i>The Portfolio for Protecting the Sensitized Paper from Exposure +to Light.</i>—The sensitized paper is very well protected +from exposure to light, if kept in a portfolio or book, the +brown paper leaves of which are considerably larger than the +sensitized sheets. The sheets may be returned to such a +book after exposure, and washed at the convenience of the +operator. They can be washed more quickly and perfectly if +<i>two</i> water-tanks are provided in which to wash them. A +few minutes' soaking will remove nearly all of the sensitizing +preparation which has not been fixed by the exposure. If +the soaking is too long continued in water that is much discolored +by the sensitizing preparation, the sheets become +saturated with the diluted preparation, and they may become +slightly colored by <i>after</i> exposure. If the first soaking is +not too long continued, and if the sheets are transferred at +once to a second bath of clean water, which is kept slowly +changing from an open faucet, they may remain there until +the soluble chemicals have been entirely extracted, and there +will be no risk of staining by after exposure. Washing +in two tanks is of more consequence when the ground is +white and the lines blue, than when the ground is blue and +the lines white.</p> + +<p><i>The Grades of Paper that are well Adapted for Blue Process +Work.</i>—I have tested many grades of paper, to ascertain if +they were well adapted for blue process work. Some grades +of brown Manila are very good; others have little specks embedded +in their surfaces which refuse to take on a blue tint; +still others, when printed upon, have white lines that are +wider than the corresponding black lines of the negative. +The blue obtained upon bond paper appears to be particularly +rich, and the whites remain pure; but bond paper +cockles badly, and the cockles remain in the finished print. +Weston's linen record is an excellent paper. It is strong, +cockles but little, and dries very smooth. A paper that is +used by Allen & Rowell, for carbon printing, is comparatively +cheap, and is an excellent paper. It is not so stiff as +the linen record, and the whites are quite as pure. It does +not cockle, neither does it curl while being sensitized. It +comes in one hundred pound rolls, and is about thirty inches +wide. The best papers are those that are prepared for photographic +work. The plain Saxe and the plain Rives both +give excellent results. Blue lines on a pure white ground +can be obtained on these papers, from photographic negatives, +without difficulty. None of the hard papers of good +grade require the use of gum in the sensitizing liquid. The +liquid penetrates the more porous papers too far when gum +is not used, and without it good whites are seldom obtained +upon porous paper.</p> + +<p><i>The Best Chemicals for this Work</i> are the <i>recrystallized</i> red +prussiate of potash and the citrate of iron and ammonia, +<a name="Page_5822" id="Page_5822"/> +<i>which is manufactured by Powers & Wightman</i>, of Philadelphia. +If the red prussiate has not been recrystallized, the +whites will be unsatisfactory and the samples of citrates of +iron and ammonia which have come to us from other +chemists than those named, have all proved unreliable for +this process.</p> + +<p><i>The Sensitizing Liquid.—Its Proportions.</i>—The blue process +was originally introduced from France, by the late Mr. A. +L. Holley. I was indebted to Mr. P. Barnes, who was with +Mr. Holley at the time, for an early account of it, and I had +the first blue process machine that was in use in New England. +Since 1876, instruction in the use of the blue process +has been given to the students of mechanical engineering of +the Massachusetts Institute of Technology, and they have +caused its introduction into many draughting offices. The +proportions of the sensitizing liquid, as originally given me +by Mr Barnes, were as follows:</p> + +<div class="center"> +<table summary="Original proportions"> +<tr> +<td align="left">Red prussiate of potash</td> +<td align="right">8 parts.</td> +</tr> +<tr> +<td align="left">Citrate of iron and ammonia </td> +<td align="right">8 parts.</td> +</tr> +<tr> +<td align="left">Gum arabic</td> +<td align="right">1 part. </td> +</tr> +<tr> +<td align="left">Water</td> +<td align="right">80 parts.</td> +</tr> +</table></div> + +<p><i>Results of Experiments.</i>—In our use, it first appeared that +the gum might be omitted from the preparation when +sufficiently hard papers were used. Next, that a preparation +containing</p> + +<div class="center"> +<table summary="More rapid preparation"> +<tr> +<td align="left">Red prussiate of potash</td> +<td align="right">2</td> +<td align="left">parts.</td> +</tr> +<tr> +<td align="left">Citrate of iron and ammonia </td> +<td align="right">3</td> +<td align="center">"</td> +</tr> +<tr> +<td align="left">Water</td> +<td align="right">20</td> +<td align="center">"</td> +</tr> +</table> +</div> + +<p>printed more rapidly. This preparation I continue to use +when much time may elapse between sensitizing and printing; +but, when the paper is to be printed immediately after +sensitizing, I use a larger proportion of citrate of iron and +ammonia. Before arriving at the conclusion that these +proportions were the best to be used, I made a series +of purely empirical experiments, beginning with the proportions:</p> + +<div class="center"> +<table summary="First in series"> +<tr> +<td align="left">Red prussiate of potash</td> +<td align="right">10 parts.</td> +</tr> +<tr> +<td align="left">Citrate of iron and ammonia </td> +<td align="right">1 part. </td> +</tr> +<tr> +<td align="left">Water</td> +<td align="right">50 parts.</td> +</tr> +</table> +</div> + +<p>and ending with the proportions:</p> + +<div class="center"> +<table summary="Last in series"> +<tr> +<td align="left">Red prussiate of potash</td> +<td align="right">1</td> +<td align="left">part.</td> +</tr> +<tr> +<td align="left">Citrate of iron and ammonia </td> +<td align="right">10</td> +<td align="left">parts.</td> +</tr> +<tr> +<td align="left">Water</td> +<td align="right">50</td> +<td align="center">"</td> +</tr> +</table> +</div> + +<p>I found the best plan for conducting these experiments to +be: To coat a sheet of the paper with a given mixture; to cut +the sheet into strips before exposure; to expose all the strips +of the sheet, at the same time, to the direct sunlight without +an intervening negative; and to withdraw them, one after +another, at stated intervals. I found that with each mixture +there was a time of exposure which would produce the +deepest blue, that with over-exposure the blue gradually +turned gray, and that if a curve should be plotted, the abscissas +of which should represent the time of exposure, and the +ordinates of which should represent the intensity of the blue +the curves drawn would have approximately an elliptical +form, so that if one knew the exact time of exposure which +would give the best result with any mixture, one might deviate +two or three minutes either way from that time without +producing a noticeable result. I have found that, with +the same paper, the same blue results with any good proportions +of the chemicals named, provided a sufficient weight +of both chemicals is applied to the surface; that an excess of +the red prussiate of potash renders the preparation less sensitive +to light, and very much lengthens the necessary time of +exposure; that the prints are finer with some excess of the +red prussiate; that an excess of the citrate of iron and +ammonia hastens the time of printing materially; that a +greater excess of the citrate causes the whites to become +badly stained by the iron, while a still greater excess of the +citrate, in a concentrated solution causes the sensitized +paper to change without exposure to light, and to produce a +redder blue or purple, which does not adhere to the paper, +but may be washed off with a sponge. I have found that +the cheapest method of reproducing inked drawings that +have been made on thick paper is not to trace them, but to +print the blues from a photographic glass negative; and also, +that the dry plate process is well adapted to such work in +offices, when one has become sufficiently experienced. Printed +matter can also most easily and inexpensively be reproduced +by the same means, when a small issue is required on each +successive year. For the reproduction of manuscript by the +blue process, the best plan that I have found has been to write +the manuscript upon the thinnest blue tinted French note-paper, +with black opaque ink—the stylographic ink is very +good—and, afterward, to dip the paper into melted paraffine, +and to dry the paper at the melting temperature. This operation, +if cheaply done, requires special apparatus. For positive +printing from the glass negative, I use a multiple frame, +by the aid of which I can print from 16 negatives at the same +time, upon a single sheet of paper. This frame is interchangeable +with the one that contains the plate glass. The +negatives are so arranged in the frame that the sheets can +be cut and bound, as in the ordinary process of book binding. +The time required for exposure, when printing from glass +negatives, varies with the negative; and, in order to secure +satisfactory results with the multiple frame it is necessary +to stop the exposure of some, while the exposure of others is +continued. I insert wooden or cloth stoppers into the frame +for the purpose of stopping the exposure of certain negatives. +When paraffined manuscript is to be printed from, I find it convenient +to have it written on sheets of small size, and to have +these mounted upon an opaque frame of brown Manila paper, +printing sixteen or more at a time, depending upon the size +of the printing frame. Many small tracings may be similarly +mounted upon a brown paper multiple frame, and may be +printed together upon a single sheet.</p> + +<p><a name="Footnote_3_1"/><a href="#FNanchor_3_1">[1]</a></p><div class="note"><p>Read June 21, 1882, before the Boston Society of Civil Engineers.</p></div> + +<p><a name="Footnote_3_2"/><a href="#FNanchor_3_2">[2]</a></p><div class="note"><p>Since this paper was read, I have seen in the office of the City Engineer +of Boston a drying case which is similar in some respects to the one that +I have devised. It has been longer in use than my own. The drawers +are simply the ordinary mosquito netting frames covered with cotton netting. +They have no fronts, but a door covers the front of the case, and +shuts out the light.</p></div> + +<hr /> + +<h2><a name="art16" id="art16"/>SPECTRUM GRATINGS.</h2> + +<p>At a recent meeting of the London Physical Society, +Prof. Rowland, of Baltimore, exhibited a number of his new +concave gratings for giving a diffraction spectrum. He explained +the theory of their action. Gratings can be ruled +on any surface, if the lines are at a proper distance apart and +of the proper form. The best surface, however, is a cylindrical +or spherical one. The gratings are solid slabs of +polished speculum metal ruled with lines equidistant by a +special machine of Prof. Rowland's invention. An account +of this machine will be published shortly. The number of +lines per inch varied in the specimens shown from 5,000 to +42,000, but higher numbers can be engraved by the cutting +diamond. The author has designed an ingenious mechanical +arrangement for keeping the photographic plates in focus. +In this way photographs of great distinctness can be obtained. +Prof. Rowland exhibited some 10 inches long, which showed + +the E line doubled, and the large B group very clearly. +Lines are divided by this method which have never been +divided before, and the work of photographing takes a mere +fraction of the time formerly required. A photographic +plate sensitive throughout its length is got by means of a +mixture of eosene, iodized collodion, and bromized collodion. +Prof. Rowland and Captain Abney, R.E., are at present +engaged in preparing a new map of the whole spectrum with +a focus of 18 feet.</p> + +<p>In reply to Mr. Hilger, F.R.A.S., the author stated that +if the metal is the true speculum metal used by Lord Rosse, +it would stand the effects of climate, he thought; but if too +much copper were put in, it might not.</p> + +<p>In reply to Mr. Warren de la Rue, Prof. Rowland said +that 42,000 was the largest number of lines he had yet required +to engrave on the metal.</p> + +<p>Prof. Guthrie read a letter from Captain Abney, pointing +out that Prof. Rowland's plates gave clearer spectra than any +others; they were free from "ghosts," caused by periodicity +in the ruling, and the speculum metal had no particular +absorption.</p> + +<p>Prof. Dewar, F.R.S., observed that Prof. Liveing and he +had been engaged for three years past in preparing a map of +the ultra-violet spectrum, which would soon be published. +He considered the concave gratings to make a new departure +in the subject, and that they would have greatly facilitated +the preparation of his map.</p> + +<hr /> + +<h2><a name="art17" id="art17"/>A NEW POCKET OPERA GLASS.</h2> + +<div class="figcenter"> +<a href="images/fig17-1.png"> +<img src="images/fig17-1-small.png" width="335" height="450" alt="Pocket Opera Glass" title="" /> +</a><br /><span class="caption">POCKET OPERA GLASS.</span> +</div> + +<p>Inasmuch as high power combined with small size is +usually required in an opera glass, manufacturers have always +striven to unite these two features in their instruments, +and have succeeded in producing glasses which, although +sufficiently small to be carried in the waistcoat pocket, are +nevertheless powerful enough to allow quite distant objects +to be clearly distinguished. Recently, a Parisian optician +has succeeded in constructing an instrument of this kind +that is somewhat of a novelty in its way, since its mechanism +allows it to be closed in such a manner as to take up no +more space than a package of cigarettes (Fig. 1.) It is constructed +as follows:</p> + +<p>AB and CD (Fig. 1) are two metallic tubes, in which slide +with slight friction two other tubes. Into the upper part of +the latter are inserted two hollow elliptical eye-pieces, which +move therein with slight friction, and which are united by the +two supports tor the wheel, <i>bb</i> (Fig. 4), and endless screw +that serve for focusing the instrument. The eyepieces, +TT, are held in the tube by means of two screws, <i>vv</i> +(Figs. 2 and 4), in such a way that they can revolve around +the latter as axes. The lenses of the eye-piece are +fixed therein by means of a copper ring. The object +glasses are placed in the ends of the tubes, AB and CD, at +<i>oo</i>.</p> + +<p>When the instrument is closed, it forms a cylinder 35 millimeters +in diameter by 11 centimeters in length. To open it, +it is grasped by the extremities and drawn apart horizontally +so as to bring it into the position shown in Fig. 2. Then it +is turned over so that the screw, V, points upward, while at +the same time the two tubes are pressed gently downward. +This causes the eye-pieces to revolve around their axes, <i>vv</i>, +and brings the two tubes parallel with each other.—<i>La +Nature.</i></p> + +<hr /> + +<h2><a name="art23" id="art23"/>ANCIENT GREEK PAINTING.</h2> + +<p>A lecture on ancient Greek painting was lately delivered by +Professor C.T. Newton, C.B., at University College, London. +The lecturer began by reminding his audience of the course of +lectures on Greek sculpture, from the earliest times to the +Roman period, which he completed this year. The main +epochs in the history of ancient sculpture had an intimate +connection with the general history of the Greeks, with their +intellectual, political, and social development. We could +not profitably study the history of ancient sculpture except +as part of the collateral study of ancient life as a whole, nor +could we get a clear idea of the history of ancient sculpture +without tracing out, so far as our imperfect knowledge +permits, the characteristics and successive stages of ancient +painting. Between these twin sister arts there had been in + +all times, and especially in Greek antiquity, a close sympathy +and a reciprocal influence. The method in dealing with the +history of Greek painting in this course would be similar to +that adopted in the course on sculpture. The evidence of +ancient authors as to the works and characteristics of Greek +painters would be first examined, then the extant monuments +which illustrate the history of this branch of art would be +described. In the case of painting, the extant monuments +were few and far between, but we might learn much by the +careful study of the mural paintings from the buried Campanian +cities, Pompeii, Herculaneum, and those found in the +tombs near Rome and Etruria. The paintings on Greek +vases would enable us to trace the history of what is called +ceramographic art from B.C. 600 for nearly five centuries onward.</p> + +<p>After noticing the traditions preserved by Pliny and +others as to the earliest painters, the lecturer passed on to +the period after the Persian war. Polygnotos of Thasos +was the earliest Greek painter of celebrity. He flourished +B.C. 480-460. At Athens he decorated with paintings the +portico called the Stoa Poikile, the Temple of the Dioscuri, +the Temple of Theseus, and the Pinakotheke on the Akropolis. +At Delphi he painted on the walls of the building +called Lesche two celebrated pictures, the taking of Troy +and the descent of Ulysses into Hades. All these were mural +paintings; the subjects were partly mythical, partly historical. +Thus in the Stoa Poikile were represented the taking +of Troy, the battle of Theseus with the Amazons, the battle +of Marathon. In the Temple of Theseus came the battle of the +Lapiths and Centaurs and the battle of the Amazons again. +In the other two Athenian temples he treated mythological +subjects. These great public works were executed during +the administration of Kimon, to whom Polygnotos stood in +the same relation us Phidias did to Perikles, the successor of +Kimon. The paintings in the Stoa Poikile were executed by +Polygnotos gratuitously, for which service the Athenians rewarded +him with the freedom of their city. His greatest and +probably his earliest works were the two pictures in the +Lesche at Delphi. Of these there was a very full description +in Pausanias. The building called Lesche was thought to have +been of elliptical form, with a colonnade on either side, separated +by a wall in the middle, and to have been about 90 ft in +length. The figures were probably life size.</p> + +<p>According to the list given by Pausanias, there were upward +of seventy in each of the two pictures. In that representing +the taking of Troy Polygnotos had brought together many +incidents described in the Cyclic epics: Menelaos Agamemnon, +Ulysses, Nestor, Neoptolemos, Antenor, Helen, Andromache, +Kassandra, and many other figures, with which the +Homeric poems have made us familiar, all appeared united +in one skillful composition, arranged in groups. The other +picture, the descent of Ulysses into Hades to interrogate +Teiresias, might be called a pictorial epic of Hades. On +one side was the entrance, indicated by Charon's boat crossing: +the Acheron, and the evocation of Teiresias by Ulysses, +besides the punishment of Tityos and other wicked men; +on the other side were Tantalos and Sisyphos. Between these +scenes, on the flanks, were various groups of heroes and +heroines from the Trojan and other legends. From the remarks +of ancient critics, it might be inferred that the genius +of Polygnotos, like that of Giotto, was far in advance of his +technical skill. Aristotle called him the most ethical of +painters, and recommended the young artist to study his +works in preference to those of his contemporary Pauson, +who was ignobly realistic, or those of Zeuxis, who had great +technical merit, but was deficient in spiritual conception. +The course will comprise four more lectures, as follows—November +17, "Greek Painters from B.C. 460 to Accession of +Alexander the Great B.C. 336—Apollodoros, Zeuxis, Parrhasios, +Pamphilos, Aristides;" November 24, "Greek +Painters from Age of Alexander to Augustan Age—Apelles, +Protogenes, Theon;" December 1, "Pictures on Greek Fictile +Vases;" December 15, "Mural Paintings from Pompeii, +Herculaneum, and other Ancient sites."</p> + +<hr /> + +<p>The new Iowa State Capitol has thus far cost $2,000,000, +and it will require $500,000 to finish it. It is 365 feet long +fron north to south, and measures 274 feet from the sidewalk +to the top of the central dome.</p> + +<hr /> + +<p class="center"><a name="Page_5823" id="Page_5823"/>[LONGMAN'S MAGAZINE.]</p> + +<h2><a name="art18" id="art18"/>ATOMS, MOLECULES, AND ETHER WAVES.</h2> + +<h3><span class="smcap">By John Tyndall, F.R.S.</span></h3> + +<p class="center">I.</p> + +<p>Man is prone to idealization. He cannot accept as final +the phenomena of the sensible world, but looks behind that +world into another which rules the sensible one. From this +tendency of the human mind, systems of mythology and scientific +theories have equally sprung. By the former the experiences +of volition, passion, power, and design, manifested +among ourselves, were transplanted, with the necessary +modifications, into an unseen universe from which the sway +and potency of those magnified human qualities were exerted. +"In the roar of thunder and in the violence of the +storm was felt the presence of a shouter and furious strikers, +and out of the rain was created an Indra or giver of rain." +It is substantially the same with science, the principal force +of which is expended in endeavoring to rend the veil which +separates the sensible world from an ultra-sensible one. In +both cases our materials, drawn from the world of the senses, +are modified by the imagination to suit intellectual needs. +The "first beginnings" of Lucretius were not objects of +sense, but they were suggested and illustrated by objects of +sense. The idea of atoms proved an early want on the part +of minds in pursuit of the knowledge of nature. It has +never been relinquished, and in our own day it is growing +steadily in power and precision.</p> + +<p>The union of bodies in fixed and multiple proportions constitutes +the basis of modern atomic theory. The same compound +retains, for ever, the same elements, in an unalterable +ratio. We cannot produce pure water containing one part, +by weight, of hydrogen and nine of oxygen, nor can we +produce it when the ratio is one to ten; but we can produce +it from the ratio of one to eight, and from no other. So also +when water is decomposed by the electric current, the proportion, +as regards volumes, is as fixed as in the case of +weights. Two volumes of hydrogen and one of oxygen invariably +go the formation of water. Number and harmony, +as in the Pythagorean system, are everywhere dominant in +this under-world.</p> + +<p>Following the discovery of fixed proportions we have that +of <i>multiple</i> proportions. For the same compound, as above +stated, the elementary factors are constant; but one elementary +body often unites with another so as to form different +compounds. Water, for example, is an oxide of hydrogen; +but a peroxide of that substance also exists, containing exactly +double the quantity of oxygen. Nitrogen also unites +with oxygen in various ratios, but not in all. The union +takes place, not gradually and uniformly, but by steps, a +definite weight of matter being added at each step. The +larger combining quantities of oxygen are thus multiples +of the smaller ones. It is the same with other combinations.</p> + +<p>We remain thus far in the region of fact: why not rest +there? It might as well be asked why we do not, like our +poor relations of the woods and forests, rest content with +the facts of the sensible world. In virtue of our mental +idiosyncrasy, we demand <i>why</i> bodies should combine in +multiple proportions, and the outcome and answer of this +question is the atomic theory. The definite weights of matter, +above referred to, represent the weights of atoms, indivisible +by any force which chemistry has hitherto brought +to bear upon them. If matter were a <i>continuum</i>—if it were +not rounded off, so to say, into these discrete atomic masses—the +impassable breaches of continuity which the law of +multiple proportions reveals, could not be accounted for. +These atoms are what Maxwell finely calls "the foundation +stones of the material universe," which, amid the wreck of +composite matter, "remain unbroken and unworn."</p> + +<p>A group of atoms drawn and held together by what chemists +term affinity is called a molecule. The ultimate parts +of all compound bodies are molecules. A molecule of water, +for example, consists of two atoms of hydrogen, which grasp +and are grasped by one atom of oxygen. When water is +converted into steam, the distances between the molecules +are greatly augmented, but the molecules themselves continue +intact. We must not, however, picture the constituent +atoms of any molecule as held so rigidly together as to render +intestine motion impossible. The interlocked atoms +have still liberty of vibration, which may, under certain +circumstances, become so intense as to shake the molecule +asunder. Most molecules—probably all—are wrecked by +intense heat, or in other words by intense vibratory motion; +and many are wrecked by a very moderate heat of the proper +quality. Indeed, a weak force, which bears a suitable +relation to the constitution of the molecule, can, by timely +savings and accumulations, accomplish what a strong force +out of relation fails to achieve.</p> + +<p>We have here a glimpse of the world in which the physical +philosopher for the most part resides. Science has been defined +as "organized common sense;" by whom I have forgotten; +but, unless we stretch unduly the definition of common +sense, I think it is hardly applicable to this world of +molecules. I should be inclined to ascribe the creation of +that world to inspiration rather than to what is currently +known as common sense. For the natural history sciences +the definition may stand—hardly for the physical and mathematical +sciences.</p> + +<p>The sensation of light is produced by a succession of waves +which strike the retina in periodic intervals; and such waves, +impinging on the molecules of bodies, agitate their constituent +atoms. These atoms are so small, and, when +grouped to molecules, are so tightly clasped together, that +they are capable of tremors equal in rapidity to those of +light and radiant heat. To a mind coming freshly to these +subjects, the numbers with which scientific men here habitually +deal must appear utterly fantastical; and yet, to minds +trained in the logic of science, they express most sober and +certain truth. The constituent atoms of molecules can vibrate +to and fro millions of millions of times in a second. +The waves of light and of radiant heat follow each other at +similar rates through the luminiferous ether. Further, the +atoms of different molecules are held together with varying +degrees of tightness—they are tuned, as it were, to notes of +different pitch. Suppose, then, light-waves, or heat-waves, +to impinge upon an assemblage of such molecules, what +may be expected to occur? The same as what occurs when +a piano is opened and sung into. The waves of sound select +the strings which respectively respond to them—the strings, +that is to say, whose rates of vibration are the same as their +own—and of the general series of strings these only sound. +The vibratory motion of the voice, imparted first to the air, +is here taken up by the strings. It may be regarded as <i>absorbed</i>, +each string constituting itself thereby a new center of +motion. Thus also, as regards the tightly locked atoms of +molecules on which waves of light or radiant heat impinge. + +Like the waves of sound just adverted to, the waves of ether +select those atoms whose periods of vibration synchronize +with their own periods of recurrence, and to such atoms deliver +up their motion. It is thus that light and radiant heat +are absorbed.</p> + +<p>And here the statement, though elementary, must not be +omitted, that the colors of the prismatic spectrum, which are +presented in an impure form in the rainbow, are due to different +rates of atomic vibration in their source, the sun. +From the extreme red to the extreme violet, between which +are embraced all colors visible to the human eye, the rapidity +of vibration steadily increases, the length of the waves of +ether produced by these vibrations diminishing in the same +proportion. I say "visible to the human eye," because +there may be eyes capable of receiving visual impression +from waves which do not affect ours. There is a vast store +of rays, or more correctly waves, beyond the red, and also +beyond the violet, which are incompetent to excite our vision; +so that could the whole length of the spectrum, visible +and invisible, be seen by the same eye, its length would be +vastly augmented.</p> + +<p>I have spoken of molecules being wrecked by a moderate +amount of heat of the proper quality: let us examine this +point for a moment. There is a liquid called nitrite of amyl—frequently +administered to patients suffering from heart +disease. The liquid is volatile, and its vapor is usually inhaled +by the patient. Let a quantity of this vapor be introduced +into a wide glass tube, and let a concentrated beam +of solar light be sent through the tube along its axis. Prior +to the entry of the beam, the vapor is as invisible as the purest +air. When the light enters, a bright cloud is immediately +precipitated on the beam. This is entirely due to the +waves of light, which wreck the nitrite of amyl molecules, +the products of decomposition forming innumerable liquid +particles which constitute the cloud. Many other gases and +vapors are acted upon in a similar manner. Now the waves +that produce this decomposition are by no means the most +powerful of those emitted by the sun. It is, for example, +possible to gather up the ultra-red waves into a concentrated +beam, and to send it through the vapor, like the beam of light. +But, though possessing vastly greater energy than the light +waves, they fail to produce decomposition. Hence the justification +of the statement already made, that a suitable relation +must subsist between the molecules and the waves of +ether to render the latter effectual.</p> + +<p>A very impressive illustration of the decomposing power +of the waves of light is here purposely chosen; but the processes +of photography illustrate the same principle. The +photographer, without fear, illuminates his developing room +with light transmitted through red or yellow glass; but he +dares not use blue glass, for blue light would decompose his +chemicals. And yet the waves of red light, measured by the +amount of energy which they carry, are immensely more +powerful than the waves of blue. The blue rays are usually +called chemical rays—a misleading term; for, as Draper and +others have taught us, the rays that produce the grandest +chemical effects in nature, by decomposing the carbonic +acid and water which form the nutriment of plants, are not +the blue ones. In regard, however, to the salts of silver, +and many other compounds, the blue rays are the most +effectual. How is it then that weak waves can produce +effects which strong waves are incompetent to produce? +This is a feature characteristic of periodic motion. In the +experiment of singing into an open piano already referred +to, it is the accord subsisting between the vibrations of the +voice and those of the string that causes the latter to sound. +Were this accord absent, the intensity of the voice might be +quintupled, without producing any response. But when +voice and string are identical in pitch, the successive impulses +add themselves together, and this addition renders +them, in the aggregate, powerful, though individually they +may be weak. It some such fashion the periodic strokes of +the smaller ether waves accumulate, till the atoms on which +their timed impulses impinge are jerked asunder, and what +we call chemical decomposition ensues.</p> + +<p>Savart was the first to show the influence of musical sounds +upon liquid jets, and I have now to describe an experiment +belonging to this class, which bears upon the present question. +From a screw-tap in my little Alpine kitchen I permitted, +an hour ago, a vein of water to descend into a +trough, so arranging the flow that the jet was steady and +continuous from top to bottom. A slight diminution of the +orifice caused the continuous portion of the vein to shorten, +the part further down resolving itself into drops. In my +experiment, however, the vein, before it broke, was intersected +by the bottom of the trough. Shouting near the descending +jet produced no sensible effect upon it. The higher +notes of the voice, however powerful, were also ineffectual. +But when the voice was lowered to about 130 vibrations a +second, the feeblest utterance of this note sufficed to shorten, +by one half, the continuous portion of the jet. The responsive +drops ran along the vein, pattered against the trough, +and scattered a copious spray round their place of impact. +When the note ceased, the continuity and steadiness of the +vein were immediately restored. The formation of the drops +was here periodic; and when the vibrations of the note accurately +synchronized with the periods of the drops, the +waves of sound aided what Plateau has proved to be the +natural tendency of the liquid cylinder to resolve itself into +spherules, and virtually decomposed the vein.</p> + +<p>I have stated, without proof, that where absorption occurs, +the motion of the ether-waves is taken up by the constituent +atoms of molecules. It is conceivable that the ether-waves, +in passing through an assemblage of molecules, might deliver +up their motion to each molecule as a whole, leaving +the relative positions of the constituent atoms unchanged. +But the long series of reactions, represented by the deportment +of nitrite of amyl vapor, does not favor this conception; +for, were the atoms animated solely by a common +motion, the molecules would not be decomposed. The fact of +decomposition, then, goes to prove the atoms to be the +seat of the absorption. They, in great part, take up the +energy of the ether-waves, whereby their union is severed, +and the building materials of the molecules are scattered +abroad.</p> + +<p>Molecules differ in stability; some of them, though hit by +waves of considerable force, and taking up the motions of +these waves, nevertheless hold their own with a tenacity +which defies decomposition. And here, in passing, I may +say that it would give me extreme pleasure to be able to +point to my researches in confirmation of the solar theory +recently enunciated by my friend the President of the British +Association. But though the experiments which I have +made on the decomposition of vapors by light might be +numbered by the thousand, I have, to my regret, encountered +no fact which prove that free aqueous vapor is decomposed +by the solar rays, or that the sun is reheated by the +combination of gases, in the severance of which it had previously +sacrificed its heat.</p> + + +<p class="center">II.</p> + +<p>The memorable investigations of Leslie and Rumford, and +the subsequent classical reasearches of Melloni, dealt, in the +main, with the properties of radiant heat; while in my investigations, +radiant heat, instead of being regarded as an +end, was employed as a means of exploring molecular condition. +On this score little could be said until the gaseous +form of matter was brought under the dominion of experiment. +This was first effected in 1859, when it was proved +that gases and vapors, notwithstanding the open door which +the distances between their molecules might be supposed to +offer to the heat waves, were, in many cases, able effectually +to bar their passage. It was then proved that while the +elementary gases and their mixtures, including among the +latter the earth's atmosphere, were almost as pervious as a +vacuum to ordinary radiant heat, the compound gases were +one and all absorbers, some of them taking up with intense +avidity the motion of the ether-waves.</p> + +<p>A single illustration will here suffice. Let a mixture of +hydrogen and nitrogen, in the proportion of three to fourteen +by weight, be inclosed in a space through which are passing +the heat rays from an ordinary stove. The gaseous mixture +offers no measurable impediment to the rays of heat. +Let the hydrogen and nitrogen now unite to form the compound +ammonia. A magical change instantly occurs. The +number of atoms present remains unchanged. The transparency +of the compound is quite equal to that of the mixture +prior to combination. No change is perceptible to the eye, +but the keen vision of experiment soon detects the fact that +the perfectly transparent and highly attenuated ammonia +resembles pitch or lampblack in its behavior to the rays of +heat.</p> + +<p>There is probably boldness, if not rashness, in the attempt +to make these ultra-sensible actions generally intelligible, +and I may have already transgressed the limits beyond which +the writer of a familiar article cannot profitably go. There +may, however, be a remnant of readers willing to accompany +me, and for their sakes I proceed. A hundred compounds +might be named which, like the ammonia, are transparent to +light, but more or less opaque—often, indeed, intensely +opaque—to the rays of heat from obscure sources. Now the +difference between these latter rays and the light rays is +purely a difference of period of vibration. The vibrations in +the case of light are more rapid, and the ether waves which +they produce are shorter, than in the case of obscure heat. +Why, then, should the ultra-red waves be intercepted by bodies +like ammonia, while the more rapidly recurrent waves +of the whole visible spectrum are allowed free transmission? +The answer I hold to be that, by the act of chemical combination, +the vibrations of the constituent atoms of the molecules +are rendered so sluggish as to synchronize with the +motions of the longer waves. They resemble loaded piano +strings, or slowly descending water jets, requiring notes of +low pitch to set them in motion.</p> + +<p>The influence of synchronism between the "radiant" and +the "absorbent" is well shown by the behavior of carbonic +acid gas. To the complex emission from our heated stove, +carbonic acid would be one of the most transparent of gases. +For such waves olefiant gas, for example, would vastly transcend +it in absorbing power. But when we select a radiant +with whose waves the atoms of carbonic acid are in accord, +the case is entirely altered. Such a radiant is found in a +carbonic oxide flame, where the radiating body is really hot +carbonic acid. To this special radiation carbonic acid is the +most opaque of gases.</p> + +<p>And here we find ourselves face to face with a question of +great delicacy and importance. Both as a radiator and as an +absorber, carbonic acid is, in general, a feeble gas. It is +beaten in this respect by chloride of methyl, ethylene, ammonia, +sulphurous acid, nitrous oxide, and marsh gas. Compared +with some of these gases, its behavior, in fact, approaches +that of elementary bodies. May it not help to +explain their neutrality? The doctrine is now very generally +accepted that atoms of the same kind may, like atoms +of different kinds, group themselves to molecules. Affinity +exists between hydrogen and hydrogen and between chlorine +and chlorine, as well as between hydrogen and chlorine. +We have thus homogeneous molecules as well as heterogeneous +molecules, and the neutrality so strikingly exhibited by +the elements may be due to a quality of which carbonic acid +furnishes a partial illustration. The paired atoms of the +elementary molecules may be so out of accord with the periods +of the ultra red waves—the vibrating periods of these +atoms may, for example, be so rapid—as to disqualify them +both from emitting those waves, and from accepting their +energy. This would practically destroy their power, both as +radiators and absorbers. I have reason to know that a distinguished +authority has for some time entertained this hypothesis.</p> + +<p>We must, however, refresh ourselves by occasional contact +with the solid ground of experiment, and an interesting +problem now lies before us awaiting experimental solution. +Suppose two hundred men to be scattered equably throughout +the length of Pall Mall. By timely swerving now and +then, a runner from St. James's Palace to the Athenæum +Club might be able to get through such a crowd without +much hinderance. But supposing the men to close up so as +to form a dense file crossing Pall Mall from north to south; +such a barrier might seriously impede, or entirely stop, the +runner. Instead of a crowd of men, let us imagine a column +of molecules under small pressure, thus resembling the +sparsely distributed crowd. Let us suppose the column to +shorten, without change in the quantity of matter, until the +molecules are so squeezed together as to resemble the closed +file across Pall Mall. During these changes of density, +would the action of the molecules upon a beam of heat passing +among them at all resemble the action of the crowd +upon the runner?</p> + +<p>We must answer this question by direct experiment. To +form our molecular crowd we place, in the first instance, a +gas or vapor in a tube 38 inches long, the ends of which are +closed with circular windows, air-tight, but formed of a substance +which offers little or no obstruction to the calorific +waves. Calling the measured value of a heat beam passing +through this tube 100, we carefully determine the proportionate +part of this total absorbed by the molecules in the +tube. We then gather precisely the same number of molecules +into a column 10.8 inches long, the one column being +thus three and a half times the length of the other. In this +case also we determine the quantity of radiant heat absorbed. +By the depression of a barometric column, we can easily and +exactly measure out the proper quantities of the gaseous +body. It is obvious that one mercury inch of vapor, in the +long tube, would represent precisely the same amount of +matter—or, in other words, the same number of molecules—as +3½ inches in the short one; while 2 inches of vapor in +the long tube would be equivalent to 7 inches in the short +one.</p> + +<p><a name="Page_5824" id="Page_5824"/> +The experiments have been made with the vapors of two +very volatile liquids, namely, sulphuric ether and hydride +of amyl. The sources of radiant heat were, in some cases, +an incandescent lime cylinder, and in others a spiral of +platinum wire, heated to bright redness by an electric +current. One or two of the measurements will suffice +for the purposes of illustration. First, then, as regards +the lime light; for 1 inch of pressure in the long tube, +the absorption was 18.4 per cent. of the total beam; while +for 3.5 inches of pressure in the short tube, the absorption +was 18.8 per cent., or almost exactly the same as the +former. For 2 inches pressure, moreover, in the long tube, +the absorption was 25.7 per cent.; while for 7 inches in the +short tube it was 25.6 per cent. of the total beam. Thus +closely do the absorptions in the two cases run together—thus +emphatically do the molecules assert their individuality. +As long as their number is unaltered, their action on radiant +heat is unchanged. Passing from the lime light to the +incandescent spiral, the absorptions of the smaller equivalent +quantities, in the two tubes, were 23.5 and 23.4 per +cent.; while the absorptions of the larger equivalent quantities +were 32.1 and 32.6 per cent., respectively. This constancy +of absorption, when the density of a gas or vapor +is varied, I have called "the conservation of molecular action."</p> + +<p>But it may be urged that the change of density, in these +experiments, has not been carried far enough to justify the +enunciation of a law of molecular physics. The condensation +into less than one-third of the space does not, it may be +said, quite represent the close file of men across Pall Mall. +Let us therefore push matters to extremes, and continue the +condensation till the vapor has been squeezed into a liquid. +To the pure change of density we shall then have added the +change in the state of aggregation. The experiments here +are more easily described than executed; nevertheless, by +sufficient training, scrupulous accuracy, and minute attention +to details, success may be insured. Knowing the respective +specific gravities, it is easy, by calculation, to determine +the condensation requisite to reduce a column of vapor +of definite density and length to a layer of liquid of definite +thickness. Let the vapor, for example, be that of sulphuric +ether, and let it be introduced into our 38 inch tube till a +pressure of 7.2 inches of mercury is obtained. Or let it be +hydride of amyl, of the same length, and at a pressure of 6.6 +inches. Supposing the column to shorten, the vapor would +become proportionally denser, and would, in each case, end +in the production of a layer of liquid exactly one millimeter +in thickness.<a name="FNanchor_4_1"></a><a href="#Footnote_4_1"><sup>1</sup></a> Conversely, a layer of liquid ether or of hydride +of amyl, of this thickness, were its molecules freed +from the thrall of cohesion, would form a column of vapor +38 inches long, at a pressure of 7.2 inches in the one case, +and of 6.6 inches in the other. In passing through the liquid +layer, a beam of heat encounters the same number of molecules +as in passing through the vapor layer: and our problem +is to decide, by experiment, whether, in both cases, the +molecule is not the dominant factor, or whether its power is +augmented, diminished, or otherwise overridden by the state +of aggregation.</p> + +<p>Using the sources of heat before mentioned, and employing +diathermanous lenses, or silvered minors, to render the +rays from those sources parallel, the absorption of radiant +heat was determined, first for the liquid layer, and then for +its equivalent vaporous layer. As before, a representative +experiment or two will suffice for illustration. When the +substance was sulphuric ether, and the source of radiant +heat an incandescent platinum spiral, the absorption by the +column of vapor was found to be 66.7 per cent. of the total +beam. The absorption of the equivalent liquid layer was +next determined, and found to be 67.2 per cent. Liquid and +vapor, therefore, differed from each only 0.5 per cent.; in +other words, they were practically identical in their action. +The radiation from the lime light has a greater power of penetration +through transparent substances than that from the +spiral. In the emission from both of these sources we have +a mixture of obscure and luminous rays; but the ratio of +the latter to the former, in the lime light is greater than in +the spiral; and, as the very meaning of transparency is perviousness +to the luminous rays, the emission in which these +rays are predominant must pass most freely through transparent +substances. Increased transmission implies diminished +absorption; and accordingly, the respective absorption of +ether vapor and liquid ether, when the lime light was used, +instead of being 66.7 and 67.2 per cent., were found to be</p> + +<table summary="Relative absorptions"> +<tr> +<td align="left">Vapor </td> +<td align="right">33.3</td> +<td align="left">per cent.</td> +</tr> +<tr> +<td align="left">Liquid</td> +<td align="right">33.3</td> +<td align="center">"</td> +</tr> +</table> + +<p>no difference whatever being observed between the two +states of aggregation. The same was found true of hydride +of amyl.</p> + +<p>This constancy and continuity of the action exerted on the +waves of heat when the state of aggregation is changed, I +have called "the thermal continuity of liquids and vapors." +It is, I think, the strongest illustration hitherto adduced of +the conservation of molecular action.</p> + +<p>Thus, by new methods of search, we reach a result which +was long ago enunciated on other grounds. Water is well +known to be one of the most opaque of liquids to the waves +of obscure heat. But if the relation of liquids to their vapors +be that here shadowed forth, if in both cases the molecule +asserts itself to be the dominant factor, then the dispersion +of the water of our seas and rivers, as invisible aqueous vapor +in our atmosphere, does not annul the action of the +molecules on solar and terrestrial heat. Both are profoundly +modified by this constituent; but as aqueous vapor is transparent, +which, as before explained, means pervious to the +luminous rays, and as the emission from the sun abounds in +such rays, while from the earth's emission they are wholly +absent, the vapor screen offers a far greater hinderance to +the outflow of heat from the earth toward space than to the +inflow from the sun toward the earth. The elevation of +our planet's temperature is therefore a direct consequence of +the existence of aqueous vapor in our air. Flimsy as that +garment may appear, were it removed terrestrial life would +probably perish through the consequent refrigeration.</p> + +<p>I have thus endeavored to give some account of a recent +incursion into that ultra-sensible world mentioned at the +outset of this paper. Invited by my publishers, with whom +I have now worked in harmony for a period of twenty +years, to send some contribution to the first number of their +new Magazine, I could not refuse them this proof of my +good will.</p> + +<p class="right">J. TYNDALL</p> + +<p class="right">Alp Lusgen, September 4, 1882</p> + +<p><a name="Footnote_4_1"/><a href="#FNanchor_4_1">[1]</a></p><div class="note"><p>The millimeter is 1-25th of an inch.</p></div> + +<hr /> + +<p>The German empire has now about 34,000,000 acres of +forest, valued at $400,000,000, and appropriates $500,000 +even year to increase and maintain the growth of trees.</p> + +<hr /> + + +<h2><a name="art19" id="art19"/>APPARATUS FOR MEASURING ELECTRICITY AT THE UPPER SCHOOL OF TELEGRAPHY.</h2> + +<p><i>Electro Tuning Forks and their Uses.</i>—On a former occasion +I described an instrument to which, in 1873, I gave the +name <i>Electro-Tuning Fork</i>, and which is nothing else than a +tuning fork whose motion is kept up electrically in such a +way as to last indefinitely, provided that the elements of the +pile are renewed gradually, and that from time to time the +metallic contact is changed, which causes, at every oscillation, +the current to pass from the pile into the magnet, which +keeps up the vibration.</p> + +<p>We reproduce herewith, in Fig. 1, a cut showing in projection +one of the simplest forms of the apparatus.</p> + +<div class="figcenter"> +<a href="images/fig19-1.png"> +<img src="images/fig19-1-small.png" width="275" height="300" alt="Fig. 1. Constant Vibrator" title="" /> +</a><br /><span class="caption">FIG. 1.—CONSTANT VIBRATOR.</span> +</div> + +<p>If we imagine the platinum or steel style, <i>s</i>, of the figure +to be done away with, as well as the platinized plate, I, and +its communication with the negative pole of the pile, P, we +shall have the ordinary instrument kept in operation electrically +by the aid of the electro-magnet, E, the style, <i>s</i>, the interrupting +plate, I, and the pile.</p> + +<p>If we preserve the parts above mentioned, the instrument +will possess the property of having vibrations of a constant +amplitude if sufficient energy be kept up in the pile. In +fact, when the amplitude is sufficiently great to cause the +style, <i>s</i>, to touch the plate, I, it will be seen that at such a +moment the current no longer passes through the electromagnet, +and the vibration is no longer maintained. The +amplitude cannot exceed an extent which shall permit the +style, <i>s</i>, to touch I.</p> + +<p>Under such conditions, the duration of the vibrations remains +exactly constant, as does also the vibratory intensity + +of the entire instrument. The measurement of time, then, +by an instrument of this kind is, indeed, as perfect as it could +well be.</p> + +<p>This complication in the arrangement of the apparatus has +no importance as regards those tuning forks the number +of whose vibrations exceeds a hundred per second, for in +such a case these are given an amplitude of a few millimeters +only; but it would be of importance with regard to instruments +whose number of vibrations is very small, and to +which it might be desirable to give great amplitude; for +then, as I have long ago shown, the duration of the oscillation +would depend a little on the amplitude, but a very +little, it is true.</p> + +<p>I shall not refer now to the applications of these instruments +in chronography, but will rather point out first the +applications in which they are destined to produce an effective +power.</p> + +<p>For this purpose it is necessary to make them pretty massive. +The number of the vibrations depends upon such massiveness, +and it is necessity to know the relation which exists +between these two quantities in order to be able to construct +an instrument under determinate conditions. I made in +former years such a research with regard to tuning forks of +prismatic form, that is to say, of a constant rectangular section +continuing even into the bent portion where the parallel +branches are united by a semicylinder, at the middle of +which is the wrought iron rod as well as the branches. The +<i>thickness</i> of the instrument is the dimension parallel to the +vibrations; its <i>width</i> is the dimension which is perpendicular +to them, and its <i>length</i> is reckoned from the extremity +of the branches up to the middle of the curved portion.</p> + +<p>It is found that the number of vibrations is independent +of the width, proportional to the thickness, and very nearly +inverse ratio of the square of the length, provided the +latter exceeds ten centimeters.</p> + +<p>If we represent the length by <i>l</i>, the thickness by <i>e</i>, and the +number of vibrations by <i>n</i>, we shall have the following +formula:</p> + +<p class="center"><i>n</i> = <i>k</i> × (<i>e</i> / <i>l</i><sup>2</sup>)</p> + +<p>in which <i>k</i> is a constant quantity whose value depends upon +the nature of the metal of which the tuning fork is made.</p> + +<p>This constant varies very little from steel to malleable +cast iron, and it may be taken as equal to 818270.</p> + +<p>Thus, then, we have a means of constructing a tuning fork +in which two of the three quantities, <i>n</i>, <i>e</i>, <i>l</i>, are given in +advance. Experience proves that no errors are committed +exceeding one or two per cent.</p> + +<p>It is seen from this that there is a means of increasing the +mass of the instrument without changing anything in the +thickness, the length or, consequently, the number of vibrations, +and this is by increasing the <i>breadth</i>.</p> + +<p>It is in this way that I have succeeded in having long massive +tuning forks made of malleable iron, giving no more +than 12 to 15 vibrations per second, and vibrating with perfect +regularity. Fig. 2, annexed, shows one of these instruments +of about 55 centimeters length, whose breadth, E, is +from 5 to 6 centimeters, and which makes about fifteen +double vibrations per second only.</p> + +<div class="figcenter" style="width: 572px;"> +<a href="images/fig19-2.png"> +<img src="images/fig19-2-small.png" width="572" height="400" alt="Fig. 2. The Electrical Tuning fork" title="" /> +</a><span class="caption">FIG. 2.—THE ELECTRICAL TUNING FORK.</span> +</div> + +<p><a name="Page_5825" id="Page_5825"/> +This number might be still further reduced, but at the +expense of our being led to exaggerate the longitudinal +dimensions of the apparatus in such a way as to make it inconvenient. +The object may be attained more simply by +loading the branches with slides supporting leaden weights, +M, of 500 grammes each. By fixing these slides at different +points on the branches, the number of vibrations can be +made to vary from simple to double, and even triple. Thus, +by fixing them at the extremity of the branches the number +of the vibrations is reduced to 5 or 6.</p> + +<p>There will be seen in the figure the electro-magnet which +keeps up the vibration. This is formed of three simple +electro-magnets, whose bobbins have a resistance of no more +than 10 ohms, and which are united in series. The interrupting +plate, P, against which the style, <i>s</i>, rests at each +vibration, is capable of a forward movement, or one of +recoil, by the aid of a screw, V, and of an eccentric movement +which is produced by a small handle, <i>m</i>, and during +which its plane remains invariable. This arrangement permits +the point of contact of the style and plate to be varied +without changing the precision with which the contact +takes place, and all the points of the plate to be slowly used +in succession before replacing it. The motion is produced +by means of a relatively weak pile, whose poles are connected +to the terminals, A and A'. Three Callaud elements +of triple surface, renewed one after the other every month +at the most, are sufficient to keep up the vibrations continuously, +day and night, without interruption, and that too +even when the instrument is employed in producing a small +mechanical power, as we shall see further on.</p> + +<p>We have now seen how electro-tuning forks may be constructed +of large dimensions, of large mass, and giving a +small number of vibrations per second.</p> + +<p>Such instruments are well fitted to perform the role of +electrical interrupters, and it was in such a character that +one of them figured in the Exhibition of the Upper School +of Telegraphy as a type of an interrupter for testing piles.</p> + +<div class="figcenter" style="width: 600px;"> +<a href="images/fig19-3.png"> +<img src="images/fig19-3-small.png" width="600" height="401" alt="Fig. 3. Arrangement for Testing Electric Piles" title="" /> +</a><span class="caption">FIG. 3.—ARRANGEMENT FOR TESTING ELECTRIC PILES.</span> +</div> + +<p>When it is desired to test a pile to ascertain the practicability +of employing it in telegraphy, it is necessary to make +it perform a work which shall be as nearly as possible identical +with that which it will be called on to do, until it is +used up, to estimate the duration of such work, to measure +regularly the constants of the pile, the electro-motive power, +and the internal resistance. Usually, in telegraphy, this +work consists in sending over a line of a certain resistance +intermittent currents, through the intermedium of suitable +manipulators. It suffices then to cause the branches of the +electro tuning fork to play the role of one of these manipulators. +For doing this the tuning fork carries two insulating +ebonite or ivory strips, B B (Fig. 3), which, at every +oscillation, abut against vertical brass springs, <i>r</i>. Each of +these latter is located in front of the platinized point of a +screw, <i>v</i>, which is affixed to a small metallic tongue. The +springs and tongues are insulated from each other, and are +mounted on a piece which may be moved by a screw, V, so +as to cause the springs of the strips, B B', to approach or +recede according to the amplitude of the instrument's vibrations. +Each spring and tongue is connected with terminals +affixed to the base of the apparatus. One of the poles of +one element, P, of the pile is connected with the tongue and +corresponding screw, while the other pole is connected with +the screw in front of it through the intermedium of a galvanometer, +<i>g</i><sup>2</sup>, which gives the intensity of the intermittent +current, and of a resistance coil, <i>b</i><sup>2</sup>, which performs the +role of an artificial telegraph line. The apparatus being set +in operation, it will be seen that the current from the pile is +emitted once at every vibration.</p> + +<p>Thus there may be exhausted as many pile elements as +there are springs, and that, too, simultaneously; and the contacts +of the screws and springs can be regulated in such a +way that the duration of the emissions shall be the same for +all.</p> + +<p>At the laboratory of the School of Telegraphy one of +these instruments has operated without interruption, day +and night, during eighteen months.</p> + +<div class="figcenter"> +<a href="images/fig19-4.png"> +<img src="images/fig19-4-small.png" width="386" height="450" alt="Fig. 4. Very Rapid Electric Tuning Fork" title="" /> +</a><br /><span class="caption">FIG. 4.—VERY RAPID ELECTRIC TUNING FORK.</span> +</div> + +<p>The apparatus shown in Fig. 4 is also an interrupting +electro-tuning fork, but it makes a much greater number of +vibrations than the preceding, and may serve for other +electric tests.</p> + +<p>The operation of the tuning fork is kept up electrically by +the aid of the screw, <i>v</i>, and the corresponding plate; of the +style, <i>s</i>, and of the fine wire spiral spring, <i>f</i>, both insulated +from the fork, from the electro-magnet, N, and from the +two wires, F F', which communicate with a pile.</p> + +<p>The interrupting system is symmetrical with the first. It +consists of the style, <i>s</i>, of the spiral spring, <i>f</i>, of the screw, +<i>v</i>, and of the plate that this carries at its extremity. The +terminal, B, which carries the spring, <i>f</i>, and the rod which +carries the screw being insulated from each other, it is only +necessary to cause to terminate therein the extremities of a +circuit comprising one pile, in order to produce in the circuit +a number of interruptions equal to that of the tuning +fork's vibrations. Provided the lengths of the springs, +<i>f</i> and <i>f'</i>, are proper, such vibrations will not be altered.</p> + +<p>Moreover, the instrument is so arranged as to produce +vibrations whose <i>duration can be varied at pleasure and kept +constant</i> during the whole time the experiments last. This +is done by modifying the <i>amplitude</i> of the vibrations; for +the greater the amplitude, the longer likewise the duration +of the contact of the style, <i>s</i>, on the corresponding plate, +and the shorter the duration of the interruption. In order +to modify the amplitude, the action of the electro-magnet +on the branches of the apparatus is made to vary. To effect +this, the electro-magnet is made movable perpendicularly by +the aid of a screw, V, between two slides, so that the core, +N, may be moved with respect to the median line of the +branches, and even be raised above them. Its action diminishes, +necessarily, while it is being raised, and the amplitude +of the vibrations likewise diminishes gradually and continuously. +It may thus be made, without difficulty, to vary +from two to three tenths of a millimeter to three or four +millimeters or more.</p> + +<p>But it is not sufficient to cause the amplitude to vary; it is +necessary to measure it and to keep it constant at the value +desired.</p> + +<div class="figcenter"> +<img src="images/fig19-5.png" width="237" height="450" alt="Fig. 5" title="" /> +<br /><span class="caption">FIG. 5.</span> +</div> + +<p>The measurement is effected by the aid of a very simple +apparatus that I have before described under the name of +the <i>vibrating micrometer</i>. This is a small square of paper +carrving a design like that shown in Fig. 5, and which is +seen in Fig. 4 glued to one of the masses, M, which serve +to vary the number of the instrument's vibrations. This +figure is in fact, an angle, one of whose sides is graduated +into millimeters, for example, and the other forms the edge +of a wide black band. The apex of the angle is above and +the divided side is perpendicular to the direction of the +vibrations.</p> + +<p>Under such conditions, when the fork is vibrating, the +apex of the angle, by virtue of the persistence of impressions +upon the retina, <i>seems</i> to advance along the graduation in +measure as the amplitude of the vibrations increases. If an + +angle has been drawn such that the slope of one of its sides +to the other is one-tenth, it is easy to see that for each millimeter +passed over <i>apparently</i> by the apex of the angle, the +amplitude will increase by two-tenths of a millimeter.</p> + +<p>This is the way, then, that the amplitude is measured. +On another hand, it suffices to keep the apex of the angle of +the micrometer immovable, in order to be sure of the constancy +of the tuning fork's amplitude; and this is done, +when necessary, by causing the screw, V, to move slightly.</p> + +<p>The instrument represented in Fig. 4 is, moreover, fixed +to a support devised by Mr. A. Duboscq, so as to make it +possible to give the tuning fork every position possible with +respect to a vertical plane; to raise it or lower it, and to +move it backward or forward so that it may be employed +for chimography, and in all those experiments in which +electro-tuning folks are used.</p> + +<p class="right">E. MERCADIER.</p> + +<hr /> + +<p class="center">[LONGMAN'S MAGAZINE.]</p> + +<h2><a name="art20" id="art20"/>OUR ORIGIN AS A SPECIES.</h2> + +<h3><span class="smcap">By Richard Owen, C.B., F.R.S.</span></h3> + +<p>There seems to be a manifest desire in some quarters to +anticipate the looked for and, by some, hoped-for proofs of +our descent, or rather ascent, from the ape.</p> + +<p>In the September issue of the <i>Fortnightly Review</i> a writer +cites, in this relation, the "Neanderthal skull, which possesses +large bosses on the forehead, strikingly suggestive of +those which give the gorilla its peculiarly fierce appearance;" +and he proceeds: "No other human skull presents so utterly +bestial a type as the Neanderthal fragment. If one +cuts a female gorilla-skull in the same fashion, the resemblance +is truly astonishing, and we may say that the only +human feature in the skull is its size."<a name="FNanchor_5_1"></a><a href="#Footnote_5_1"><sup>1</sup></a></p> + +<p>In testing the question as between Linnæus and Cuvier of +the zoological value of the differences between lowest man +and highest ape, a naturalist would not limit his comparison +of a portion of the human skull with the corresponding one +of a female ape, but would extend it to the young or immature +gorilla, and also to the adult male; he would then find +the generic and specific characters summed up, so far, at +least, as a portion or "fragment" of the skull might show +them. What is posed as the "Neanderthal skull" is the roof +of the brain-case, or "calvarium" of the anatomist, including +the pent-house overhanging the eye-holes or "orbits." +There is no other part of the fragment which can be supposed +to be meant by the "large bosses" of the above quotation. +And, on this assumption, I have to state that the +super-orbital ridge in the calvarium in question is but little +more prominent than in certain human skulls of both higher +and lower races, and of both the existing and cave-dwelling +periods. It is a variable cranial character, by no means indicative +of race, but rather of sex.</p> + +<p>Limiting the comparison to that on which the writer +quoted bases his conclusions—apparently the superficial +extent of the roof plate—its greater extent as compared with +that of a gorilla equaling, probably, in weight the entire +frame of the individual from the Neanderthal cave, is +strongly significant of the superiority of size of brain in the +cave-dweller. The inner surface moreover indicates the more +complex character of the soft organ on which it was moulded; +the precious "gray substance" being multiplied by certain +convolutions which are absent in the apes. But there is +another surface which the unbiased zoologist finds it requisite +to compare. In the human "calvarium" in question, +the mid-line traced backward from the super-orbital ridge +runs along a smooth track. In the gorilla a ridge is raised +from along the major part of that tract to increase the surface +giving attachment to the biting muscles. Such ridge in +this position varies only in height in the female and the male +adult ape, as the specimens in the British Museum demonstrate. +In the Neanderthal individual, as in the rest of mankind, +the corresponding muscles do not extend their origins +to the upper surface of the cranium, but stop short at the +sides forming the inner wall or boundary of what are called +the "temples," defined by Johnson as the "upper part of +the sides of the head," whence our "biting muscles" are +called "temporal," as the side-bones of the skull to which +they are attached are also the "temporal bones." In the +superficial comparison to which Mr. Grant Allen has restricted +himself in bearing testimony on a question which +perhaps affects our fellow-creatures, in the right sense of the +term, more warmly than any other in human and comparative +anatomy, the obvious difference just pointed out ought +not to have been passed over. It was the more incumbent +on one pronouncing on the paramount problem, because the +"sagittal ridge in the gorilla," as in the orang, relates to +and signifies the dental character which differentiates all +<i>Quadrumana</i> from all <i>Bimana</i> that have ever come under +the ken of the biologist. And this ridge much more +"strikingly suggests" the fierceness of the powerful brute-ape +than the part referred to as "large bosses." Frontal +prominences, more truly so termed, are even better developed +in peaceful, timid, graminivorous quadrupeds than in +the skulls of man or of ape. But before noticing the evidence +which the teeth bear on the physical relations of man +to brute, I would premise that the comparison must not be +limited to a part or "fragment" of the bony frame, but to +its totality, as relating to the modes and faculties of locomotion.</p> + +<p>Beginning with the skull—and, indeed, for present aim, +limiting myself thereto—I have found that a vertical longitudinal +section brings to light in greatest number and of +truest value the differential characters between lowest <i>Homo</i> +and highest <i>Simia</i>. Those truly and indifferently interested +in the question may not think it unworthy their time—if it +has not already been so bestowed—to give attention to the +detailed discussions and illustrations of the characters in +question in the second and third volumes of the "Transactions +of the Zoological Society."<a name="FNanchor_5_2"></a><a href="#Footnote_5_2"><sup>2</sup></a> The concluding memoir, +relating more especially to points of approximation in cranial +and denial structure of the highest <i>Quadrumane</i> to the +lowest <i>Bimane</i>, has been separately published.</p> + +<p>I selected from the large and instructive series of human +skulls of various races in the Museum of the Royal College +of Surgeons that which was the lowest, and might be called +most bestial, in its cranial and dental characters. It was +from an adult of that human family of which the life-characters +are chiefly but truly and suggestively defined in +the narrative of Cook's first voyage in the Endeavor.<a name="FNanchor_5_3"></a><a href="#Footnote_5_3"><sup>3</sup></a></p> + +<p>Not to trespass further on the patience of my readers, I +may refer to the "Memoir on the Gorilla," 4to, 1865. Plate +xii. gives a view, natural size, of the vertical and longitudinal + +section of an Australian skull; plate xi. gives a similar +view of the skull of the gorilla. Reduced copies of these +views may be found at p. 572, figs. 395, 396, vol. ii, of my +"Anatomy of Vertebrates."</p> + +<p>As far as my experience has reached, there is no skull +displaying the characters of a quadrumanous species, as that +series descends from the gorilla and chimpanzee to the +baboon, which exhibits differences, osteal or dental, on +which specific and generic distinctions are founded, so +great, so marked, as are to be seen, and have been above +illustrated, in the comparison of the highest ape with the +lowest man.</p> + +<p>The modification of man's upper limbs for the endless +variety, nicety, and perfection of their application, in fulfillment +of the behests of his correspondingly developed +brain—actions summed up in the term "manipulation"—testify +as strongly to the same conclusion. The corresponding +degree of modification of the human lower limbs, to +which he owes his upright attitude, relieving the manual +instruments from all share in station and terrestrial locomotion—combine +and concur in raising the group so characterized +above and beyond the apes, to, at least, ordinal distinction. +The dental characters of mankind bear like testimony. +The lowest (Melanian), like the highest (Caucasian), +variety of the bimanal order differs from the quadrumanal +one in the order of appearance, and succession to the first +set of teeth, of the second or "permanent" set. The foremost +incisor and foremost molar are the earliest to appear +in that scries; the intermediate teeth are acquired sooner than +those behind the foremost molar.<a name="FNanchor_5_4"></a><a href="#Footnote_5_4"><sup>4</sup></a></p> + +<p>In the gorilla and chimpanzee, the rate or course of progress +is reversed; the second true molar, or the one behind +the first, makes its appearance before the bicuspid molars +rise in front of the first; and the third or last of the molars +behind the first comes into place before the canine tooth has +risen. This tooth, indeed, which occupies part of the interval +between the foremost incisor and foremost molar, is the +last of the permanent set of teeth to be fully developed in +the <i>Quadrumana</i>; especially in those which, in their order, +rank next to the <i>Bimana</i>. To this differential character add +the breaks in the dental series necessitated for the reception +of the crowns of the huge canines when the gorilla or chimpanzee +shuts its mouth.</p> + +<p>But the superior value of developmental over adult anatomical +characters in such questions as the present is too well +known in the actual phase of biology to need comment.</p> + +<p>In the article on "Primeval Man," the author states that +the Cave-men "probably had lower foreheads, with high +bosses like the Neanderthal skull, and big canine teeth like +the Naulette jaw."<a name="FNanchor_5_5"></a><a href="#Footnote_5_5"><sup>5</sup></a></p> + +<p>The human lower jaw so defined, from a Belgian cave, +which I have carefully examined, gives no evidence of a +canine tooth of a size indicative of one in the upper jaw +necessitating such vacancy in the lower series of teeth which +the apes present. There is no such vacancy nor any evidence +of a "big canine tooth" in that cave specimen. And, with +respect to cave specimens in general, the zoological characters +of the race of men they represent must be founded on the +rule, not on an exception, to their cranial features. Those +which I obtained from the cavern at Bruniquel, and which +are now exhibited in the Museum of Natural History, were +disinterred under circumstances more satisfactorily determining +their contemporaneity with the extinct quadrupeds +those cave-men killed and devoured than in any other spelæan +retreat which I have explored. They show neither +"lower foreheads" nor "higher bosses" than do the skulls +of existing races of mankind.</p> + +<p>Present evidence concurs in concluding that the modes of +life and grades of thought of the men who have left evidences +of their existence at the earliest periods hitherto discovered +and determined, were such as are now observable in +"savages," or the human races which are commonly so +called.</p> + +<p>The industry and pains now devoted to the determination +of the physical characters of such races, to their ways of +living, their tools and weapons, and to the relations of their +dermal, osteal, and dental modifications to those of the mammals +which follow next after <i>Bimana</i> in the descensive series +of mammalian orders, are exemplary.</p> + +<p>The present phase of the quest may be far from the bourn +to yield hereafter trustworthy evidence of the origin of man; +but, meanwhile, exaggerations and misstatements of acquired +grounds ought especially to be avoided.</p> + +<p><a name="Footnote_5_1"/><a href="#FNanchor_5_1">[1]</a></p><div class="note"><p>Grant Allen, "On Primitive Man," p. 314.</p></div> + +<p><a name="Footnote_5_2"/><a href="#FNanchor_5_2">[2]</a></p><div class="note"><p>"Oseteological Contributions to the Natural History of the Orangs +(<i>Pithecus</i>) and Chimpanzees (<i>Troglodites niger</i> and <i>Trog. gorilla</i>)."</p></div> + +<p><a name="Footnote_5_3"/><a href="#FNanchor_5_3">[3]</a></p><div class="note"><p>Hawkesworth's 4th ed., vol. iii., 1770, pp. 86, 137, 229. The skull in +question is No 5,394 of the "Catalogue of the Osteology" in the above +Museum, 4to, vol. ii, p. 823, 1853.</p></div> + +<p><a name="Footnote_5_4"/><a href="#FNanchor_5_4">[4]</a></p><div class="note"><p>"Odontography," 4to, 1840-44, p. 454, plates 117, 118, 119.</p></div> + +<p><a name="Footnote_5_5"/><a href="#FNanchor_5_5">[5]</a></p><div class="note"><p><i>Fortnightly Review</i>, September, p. 321.</p></div> + +<hr /> + +<h2><a name="art21" id="art21"/>THE ABA OR ODIKA.</h2> + +<h3><span class="smcap">By W.H. Bacheler, M.D.</span></h3> + +<p>Among the many luxuriant and magnificent forest trees +of equatorial West Africa, none can surpass, for general +beauty and symmetry, that which is called by the natives +the "aba." When growing alone and undisturbed, its +conical outline and dark green foliage remind one very much +of the white maples of the northern United States, by a +distant view, but, on a nearer approach, a dissimilarity is +observed. Wherever, in ravines or near the banks of rivers, +the soil is moist the most part of the year, there the aba +chooses to grow, and during the months of June and July +the falling fruits permeate the atmosphere with a delicious +fragrance not similar to any other. This, in form, size, and +general appearance, is very much like mango apples, so that +the natives call mangoes the "white man's aba;" but the +wild aba is not much eaten as a fruit, one or two being sufficient +for the whole season. The kernel, or seed, is the +important and useful part.</p> + +<p>When the fallen fruit covers the ground, much as apples +do in America, the natives go in canoes to gather it, and the +number harvested will be in proportion to the industry of the +women. The aba plum is about the size of a goose's egg, +of a flattened, ovoid shape, and, when ripe, a beautiful golden +color. It consists of three distinct parts: the rind, the pulp, +and the seed. The pulp consists of a mass extensively interwoven +with strong filaments, which apparently grow out of +the seed and are with great difficulty separated from it. +The seed, reniform in shape, is bivalved, and constitutes +about two-thirds of the bulk of the entire plum, and the inner +kernel two-thirds the bulk of the seed.</p> + +<p>In consequence of it being such a high tree and growing +in such inconvenient places, I have been unable to procure +a specimen of the flowers.</p> + +<p>As soon as the fruit is brought to the village, all the inhabitants +assemble with cutlasses and engage in the work of +opening the plums and removing the kernels. The former +are thrown away as useless. The seeds are evenly spread on +the top of a rack of small sticks, under which a fire is built +in the morning, and subjected to the smoke and heat of +an entire day. Toward evening the heat is greatly augmented, + +and in a couple of hours the process is completed. The +kernels are now soft, and the oil oozing from them, and while +yet in this condition they are thrown into an immense +trough and throughly beaten and mashed with a pestle.</p> + +<p>Baskets, with banana leaves spread in the inside to prevent +the escape of the product, are in readiness, and it is put into +them and pressed down. The next day these baskets are +suspended in the sun, and at night are brought into the houses +to congeal. The process is now finished. The cakes are removed +by inversion of the baskets and "bushrope" tied +around them, by which the pieces are carried. As thus prepared, +odika is highly esteemed by the natives as an article +of food, being made into a kind of thick gravy and eaten with +boiled plantains.</p> + +<p>While at an interior mission station on the Ogowe +River, I made some experiments in soap making. With +palm oil I succeeded very well, using for an alkali the old-fashioned +lye of ashes. But I was disappointed with the odika, +though I learned some peculiar characteristics of it as a grease. +By boiling the crude odika, I was unable, as I hoped, to +separate the oleaginous from the extraneous matter, of +which it contains a large proportion, but when the above-mentioned +lye was used instead of water, the mass, instead +of saponifying, merely separated; the grease, resembling +very much in all particulars ordinary beef tallow, rising to +the top of the caldron, while the refuse was precipitated.</p> + +<p>After clarifying this, it answers instead of oil of theobroma +very nicely, and I have used it considerably in making ointments +and suppositories with pleasing results.</p> + +<p>Gaboon, W. Africa, Aug., 1882.—<i>New Remedies.</i></p> + +<hr /> + +<h2><a name="art22" id="art22"/>CALIFORNIA CEDARS.</h2> + +<p>The incense cedar (<i>Libocedius decurrens</i>) is one of the +valued trees of the California coast and mountains. It is +eminently noted for great rapidity of growth, wonderful +lightness, stiffness, and extraordinary durability. A thousand +uses have sprung up and are multiplying around this +interesting cedar as its most inestimable qualities become +better known. Fortunately it is one of the most extensively +distributed trees of the Pacific—found from the coast range +north, south to San Diego, Sierra Nevada, southern Oregon, +and most of the interior mountain region from 2,000 to 4,000 +feet, and it even thrives quite well at 6,600 feet altitude, +but seeming to give out at 7,000 feet, though said to extend +to 8,500 feet, which is questionable. As usual with the sylva, +flora, and fauna, this also is found lowest along the coast, +where it finds the requisite temperature and other essentials, +with combined moisture. The base and lower trunk somewhat +resembles the Western juniper (<i>J. occidentalis</i>). It is to +be noted in general that trees of such broad, outwardly +sweeping, or expanded bases seldom blow over, and to the +perceptive and artistic eye their significant character is one +of firmness and stability. One hundred to two hundred +feet high, six to nine feet in diameter (rarely larger) the shaft +is often clear of limbs 80 to 100 feet, and although the lower +limbs, or even dry branches, may encumber the middle portion, +pin-knots do not damage the timber. The massive +body tapers more rapidly above than redwood, and is less +eccentric than juniper, yet its general port resembles most +the best specimens of the latter. The light cinnamon bark +is thick and of shreddy-fibered texture, but so concretely +compacted as to render the surface evenly ridged by very +long, big bars of bark. These sweep obliquely down on the +long spiral twist of swift water lines. The top is conic, the +foliage is in compressed, flattened sprays, upright, thickened, +and somewhat succulent; if not a languid type, at least in +no sense rigid. It bears some resemblance to the great +Western arborvitæ (<i>Thuja gigantea</i>), but the tiny leaf-scales +are opposite and quite awl-pointed. The general hue of +the foliage is light yellowish green, warmly tinted, golden +and bead tipped, with tiny, oblong male catkins, as the fruit +ripens in October and November. The cones are pendulous +from the tips of twigs, oblong, and seldom over three-quarters +of an inch long, little more than one-third as thick, +and for the most part a trifle compressed. The wood is a +pale cream-tint in color—a delicate salmon shade. This +would hardly warrant the name white cedar, sometimes +applied to it, as well as the giant arborvitæ. The extreme +lightness of the lumber and its sweetness for packing boxes +will commend it for express and commercial purposes, +for posts and fencing, and especially railway ties, for +sleepers, stringers, and ground timbers of all varieties, and +for unnumbered uses, a tithe of which cannot be told in a +brief notice. Formerly these trees were cut away and +burned up, to clear the track for redwood, tamarack, and +ponderous pith-pines, etc.; now all else is superseded by this +incense cedar. Thus is seen how hasty and ill-advised +notions give place to genuine merit.</p> + +<p>A fungus (<i>dædalus</i>) attacks and honeycombs it; and riddled +as it may occasionally be, still, if spike or nail finds +substance enough to hold, or sufficient solidity to resist +crushing, then, for many purposes, even such lumber is +practically as good as the soundest timber; because when +the tree dies the fungus dies, and thenceforth will absorb no +more moisture than the soundest part, and is alike imperishable, +contrary to common experience in similar cases. +This is a timber nearly as lasting as solid granite. For +ship or boat lumber, the clear stuff from sound wood is so +exceedingly light, stiff, and durable, and so plenty and available, +that few timbers excel it, unless the yellow cedar or +cyprus (<i>Cupressus nutkaensis</i>) is excepted, which is a little +tougher, stronger, perhaps more elastic, and equally +durable, if judged apart from thorough tests and +careful data, which, it has been remarked, the apathy +or ignorance of some governments appear to deem unworthy +their sublime attention. There are said to be in +California a thousand times more and better kinds of naval +timbers on government lands as important to preserve as the +live oaks of the South Atlantic States. It has been asserted +as probable that, after due investigation, California would +be found to possess a vast amount of the best naval timber +in the world, a hundredfold more lasting than the best now +in use, if a few woods are excepted, of which there is understood +to be no very adequate supply.</p> + +<p>The great Washington cedar (<i>Sequoia gigantea</i>) is another +important California tree. The great sequoian timber belt +lies along the Sierras, upon the first exposed mountain side—moraines +of recent retiring glaciers—that face the Pacific, +from Calaveras on the north to near the head of Deer Creek +on the south—a distance of 200 miles, or a little above 38 +degrees north to a little below 36 degrees; altitude 5,000 to +8,000 feet, and rarely 8,400 feet. The belt is broken by two +gaps, each 40 miles wide, caused by manifest topographical +and glacial reasons, one gap between Calaveras and Tuolumne, +the other between Fresno and King's River; thence +the vast forest trends south, across the broad basins of +Kaweah and Tule, a distance of 70 miles, on fresh moraine +soil, ground from high mountain flanks by glaciers. The + +inscriptions are scarcely marred by post glacial agents, and +the contiguous water-worn marks are often so slight in the +rock-bound streams as to be measured by a few inches. +Rarely does one of these sound and vigorous cedars fall, and +those that do will lie 800 to 1,000 years, scarcely less perishable +than the granite on which they grew. The great +sequoian ditches, dug at a blow by their fall, and the tree +tumuli, always turned up beside the deep root-bowls, remain; +but, scientists assert, not a vestige of one outside the present +forests has yet presented itself, hence the area has not been +diminished during the last 8,000 or 10,000 years, and probably +not at all in post glacial times. These colossal sequoias +rise 275, 300, and even 400 feet aloft; are 20 to 30, and in some +rare cases 40 feet in diameter, looking like vast columnar +pillars of the skies. No known trees of the world compare +with them and their kin, the redwoods, for the focused proximity +of such a marvelous amount of timber within limited +areas—as it were, the highest standard of timber-land +capacity. The stage coach passes through one; 120 children +and a piano crowd inside another; a trunk furnishes a +house for cotillon parties to dance "stout on stumps;" +a horse and rider travel within the burnt-out hollows of +others, and so on. A single tree would furnish a two-rail +fence, 20 to 30 miles long. The tree has great value for +wood and lumber.—<i>N.W. Lumberman.</i></p> + +<hr /> + +<p>A catalogue containing brief notices of many important +scientific papers heretofore published in the SUPPLEMENT, +may be had gratis at this office.</p> + +<hr /> + +<h3>The</h3> +<h2>Scientific American Supplement.</h2> + +<p class="center"><b>PUBLISHED WEEKLY.</b></p> + +<p class="center"><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> + +<hr /> + +<p>All the back numbers of <span class="smcap">The Supplement</span>, from the +commencement, January 1, 1876, can be had. Price, 10 +cents each.</p> + +<hr /> + +<p>All the back volumes of <span class="smcap">The Supplement</span> can likewise +be supplied. Two volumes are issued yearly. Price of +each volume, $2.50, stitched in paper, or $3.50. bound in +stiff covers.</p> + +<hr /> + +<p>Combined rates—One copy of <span class="smcap">Scientific American</span> +and one copy of <span class="smcap">Scientific American Supplement</span>, one +year, postpaid, $7.00.</p> + +<p>A liberal discount to booksellers, news agents, and canvassers.</p> + +<p class="center"><b>MUNN & CO., Publishers</b>,<br /> +261 Broadway, New York, N.Y.</p> + +<hr /> + +<h2>PATENTS.</h2> + +<p>In connection with the <b>Scientific American</b>, Messrs. <span class="smcap">Munn & Co</span> +are Solicitors of American and Foreign Patents, have had 35 years experience, +and now have the largest establishment in the world. Patents are +obtained on the best terms.</p> + +<p>A special notice is made in the <b>Scientific American</b> of all Inventions +patented through this Agency, with the name and residence of the +Patentee. By the immense circulation thus given, public attention is directed +to the merits of the new patent, and sales or introduction often +easily effected.</p> + +<p>Any person who has made a new discovery or invention can ascertain, +free of charge, whether a patent can probably be obtained, by writing to +<span class="smcap">Munn & Co.</span></p> + +<p>We also send free our Hand Book about the Patent Laws. Patents, +Caveats, Trade Marks, their costs, and how procured, with hints for +procuring advances on inventions. Address</p> + +<p class="center"><b><span class="smcap">Munn & Co.</span>, 261 Broadway, New York.</b></p> + +<p>Branch Office, cor. 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