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Eleventh Year. 

 Vol. XXII. No. 545. 



JULY 14, 1893. 



Single Copies, Ten Cents. 

 3.50 Per Year, in Advance. 



Contents. 



The Wrens of Travis Codntt, Texas. Chas. 



D. Oldright 15 



Metallic Carbides. F. P. Venable 16 



Philosophy in the College CuaBicuLUM. 



Holmes Di/sinf/er .- 16 



British Stone Circles. — III. Derbyshire 



Circles. A. L. Lewis 17 



'Charaka Samhita. F. a, Hassler 17 



A New Theory of Light Sensation. Christine 



Ladd Franklin 18 



The Capabilities of Photography not TTn- 



limfted for Illustrating All Classes 



of Objects. O. G, Mason 20 



Letters to the Editor. 



Worms on the Brain of a Bird. G. H. French. 20 

 The International Botanical Congress at 



Madison. H.J.Webber 81 



A Plea for a Fair Valuation of Experimental 

 Physiology in Biological Courses. J. Chris- 

 tian Bay 81 



Mr. McGee and the Washington Symposium. 



CarlBarus 23 



The Lac de Marbre Trout, A New Species. 



S. Garman 83 



Tucumoari. Robt. T. Hill 2:j 



Chloropia. E. W. Sci-ipture 25 



Trees as a Factor in Climate. J. W. Slater. 25 



Mineral Wax. C. D. JSiscox 25 



Book Reviews 25,26,87 



Entered at the Post-Offlce of New York, N.Y., as 

 Second-Class Mall Matter. 



Walker Prizes in Nataral History. 



The Boston Society of Natural HUtory 



offers a first prize of from $60 to $100 and a second 

 prize of a sum not exceeding $50 for the best me- 

 moirs, in English, on one of the following sub- 

 jects: 



1. The relations of inflorescence to cross-fertiliza 

 tion illustrated by the plants of Eastern Masaa. 

 chusetts. 



2. What depths of formerly overlying rocks, now 

 removed by denudation, may be inferred from the 

 structure of various rocks in Eastern Massachu- 

 setts ? 



3. Experiments affording evidence for or against 

 the theory of evolution. 



Each memoir must be accompanied by a sealed 

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 the manuscript, and must be handed to the Secre- 

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Prizes will not be awarded unless the memoirs are 

 of adequate merit. 



SAMUEL HENSHAW, Secretary. 



Boston, July 3, 1303. 



You Ought to Read 



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Only one dollar till July, 1894. 



A scientific newspaper for unscientiflc readers. 

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The Batrachians and Reptiles of Indiana. 



A Work of 204 pages, with .3 plates of 12 figures. 

 Contains full descriptions of nearly one hundred 

 species of Batrachians and Reptiles, together with 

 abundant notes on their habits. The identification 

 of the species made easy by means of analytical 

 tables. By O. P. Hay, Ph.D. Price, in paper cover 

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The Ornamental Penman's Pocketbook of Alpha- 

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 Universal Handybook on Every-day Electrical Mat- 

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SEW METHOD OF PROTECTING BUILDINGS FROM LIGHTNING. 

 SPARE THE ROD AND SPOIL THE HOUSE! 



Ijlghtnlag Destroys. Shall it he Tour House or a Pound of Copper? 



PROTECTION FROM LIGHTNING. 

 What is the Problem ? 



In seeking a means of protection from llghtniQg-discharges, wo have In view 

 twoobjects,— the oue the prevention of damage to buildings, and the other 

 the prevention of Injury to life. In order to destroy a building In whole or In 

 part, It Is necessary that work should be done ; that Is, as physicists express 

 ■it, energy is reqilred, Jast before the UgMniug-discharge takes place, the 

 energy capable of doing the damage which we seek to prevent exists in the 

 -column of air extending from the cloud to the earth in some form that makes 

 It capable of appearing as what we call electricity. We will therefore call it 

 electrical energy. Wnat this electrical energy Is, it Is not necessary for us to 

 consider In this place ; but that it exists there can be no doubt, as it manifests 

 Itself In the destruction of buildings. The problem that we have to doal with, 

 therefore, is the conversion of this energy into some other form, and the ac- 

 ■complishment of this in such a way as shall resuU in the least injury to prop- 

 •erty and life. 



Why Have the Old Rods Failed ? 



When Ughtuing-rods were first proposed, the science of energetics was en- 

 tirely undeveloped ; that is to say, in the middle of the last century scientific 

 men had not come to recognize the fact that the different forms of energy — 

 teat, electricity, mechanical power, etc.— were convertible one into the otner, 

 and that each could produce Just so much of each of the other forms, and no 

 more. The doctrine ot the conservation and correlation of energy was first 

 clearly worked out in the early part of this century. There were, however, 

 ■some facte known in regard to electricity a hundred and torty years ago ; and 

 among these were tue attractiDg power of points for an electric spark, and the 

 -conducting power of metals. Lightning-rods were therefore Introduced with 

 the idea that the electricity existing In the lightning-discharge could be con- 

 veyed around the building which It was proposed to protect, and that the 

 bulldiag would thus be saved. 



The question as to dissipation of the energy Involved was entirely ignored, 

 naturally ; and from that time to this, in spite of the best endeavors of those 

 iuierested. lightning-rods constructed in accordance with Franklin's principle 

 have not furnished satisfactory protection. The reason for this u apparent 

 when it Is considered that the electrical energy existing In the atmosphere 

 before the discharge, or, more exactly, in the column of dielectric from the 

 ■cloud to the earth, above referred to, reaches its maximum value on the sur- 

 face of the conductors that chance to be within the column of dielectric; so 

 that the greatest display of energy will be on the surface of the very lightning- 

 rods that were meant to protect, and damage results, as so often proves to be 

 the case. 



It will be understood, of course, that this display of energy on the surface 

 of the old lightning-rods Is aided by their being more or Usd Insulated from 

 the earth, but in any event the very existence of such a mass of metal as an 

 ■old llghtnlng-rod can only tend to produce a disastrous dissipation of electrical 

 -energy upon its surface,— " to draw the lightning," as It is so commonly put. 



Is there a Better Means of Protection? 



Having cleared our minds, therefore, of any idea of conducting electricity, 

 and keeping clearly In view the fact that in providing protection agaln&t lights 

 uing we must furnish some means by which the electrical energy may be 

 ■harmlessly dissipated, the question arises, *■' Caa an Improved form bd given 

 40 the rod, so that It shall a'd in this dissipation 7 " 



As the electrical energy involved manifests itself on the surface of conduc- 

 tors, the Improved rod should be metallic ; but, instead of making a large rod 

 suppose that we make It comparatively small in size, so that the total amount 

 of metal running from the top of the house to &ome point a little below the 

 foundations shall not exceed one pound. Suppose, again, that we introduce 

 numerous insulating Joints in this rod. We shall then have a rod that experi- 

 ence shows will be readily destroyed — will be readily dissipated —wtien a 

 discharge takes place; and it will be evident, that, so far as the electrical en- 

 ergy is consumed in doing this, there will be the less to do other damag ^. 



The only point that remains to be proved as to the utility of such a rod Is to 

 show that the dissipation of such a conductor does not ttnd to injure other 

 bodies in its immediate vicinity. On this poin: I caj only say that I have 

 found no case where such a conductor (for Instance, a bell wire) has been dis- 

 sipated, even if resting against a plastered wall, where there has been any 

 material damage done to surrounding objects. 



Of course. It is readily understood that such an explosion cannot take place 

 In a confined space without the rupture of the walls (the wire cannot be 

 boarded over); but In every case that I have found recorded this dissipation 

 takes place Just as gunpowder burns when spread on a board. The objects 

 against w^lch the cundujtor rests may be stained, but they are not shattered 



I woLild therefore make clear this diatiuctlou between the action of electri- 

 cal energy when dissipated on the surface of a large conductor and when dis- 

 sipated on the surface of a comparatively small or easily di:isipated conductor. 

 When dissipated on the surface of a large conductor, — a conductor so strong 

 as to resist the explosive efidcr, — damage results to objects around. When 

 dissipated on the surface of a small conductor, the conductor goes, but the 

 other objects around are saved 



A Typical Case of the Action of a Small Conductor. 



Franklin, in a letter to ColUnson read before the London Royal Society, 

 Dec. 18, 1755, describing the partial destruction by llghtiiiug of a church-tower 

 at Newbury, Mass , wrote, " Near the bell was fixed an Iron hammer to strike 

 the hours ; and from the rail of the hammer a wire went down through a small 

 gimlet-hole in tne floor that the bell stood upon, and through a second floor in 

 like manner; then horizontally under and near tbe plastered ceiliug of that 

 second floor, till it came near a p'astered wall ; then down by the side of that 

 wall to a clock, which stood about twenty feet below the bell. The wire was 

 not bigger than a common knltiiug needle. The spire was split all to piece- 

 by the lightning, and the parts flung in all di. ectious over the sq iare In whlcL 

 the church stood, so that nothing remained above the bell. The llgbtiice 

 passed between the hammer and the clock in the above-mentijued w'.re 

 without hurtlug either of the floors, or having any effect upou them (except 

 making the gimlet-holes, through which the wire passed, a llttl i bigger), and 

 without hurling the plastered wall, or any part of the building, so far as the 

 aforesaid wire and tbe pendulum-wire ot the clock extended; whi^h latter 

 wire was about the thickness of a goose-qullI. From the end of the pendu- 

 lum, down q lite to the ground, the bull Jiug was exceedingly rent and dam- 

 aged. . . . No pirt of the aforementioned long, small wire, between the clock 

 and the hammer, could be found, except about two Inches that hung to the 

 tail of the hammer, and about as much that was fastened to the clock; the 

 rest being exploded, and ltd particles dissipated In smoke and air, a^ gun- 

 powder is by common fire, and had only left a black smutty track on the plas- 

 tering, three or four inches broad, darkest in the middle, and fainter towards 

 the edges, all along the celling, under which It pasied, aud down the wall. ' 



One hundred feet of the Hodges Patent Lighinlug Dispeller imade uuder 

 patents of N. D. C. Hodges, Editor of Science) will be mailed, pos:pald, to any 

 address, on receipt of five dollars {$5i. 



Correspondence -ioUcited. Agents uanted, 



AMERICAN LIGHTNING PROTECnON CO., 



S74r Broadway, lS^e^v Vorlv Citv. 



