ENC 





Ei.iivE.NTir Year. 

 Vol. XXII. No. 549. 



AUGUST 11, 1893. 



Single Cni'iics, Tkn Cents. 

 $3.50 Pek Year, in Advanxe. 



Contents 



Botany at the Fair. H. L. Bolley 71 



Biolog ical Survey o£ Indiana 72 



Science in Australasia 72 



Progress in Sanitary Science in Massachusetts. 



George W. Fuller 73 



Asepsis—Prevention Better Tlian Cure. Albert 



S. Ashmead, M. D 7., 



The "Gopher Frog." P. C. Test il!!!'..'. 75 



Altitude as the Cause of the Glacial Period. 



Warren Upham 75 



Notes on the Distribution of Some of the Con- 

 ifers of North-Western Canada. T. B. 



Tyrrell 76 



The Affinities of Basque and Berger. C. I. Tay- 

 lor 77 



Letters to the Editor. 



The So-called Sand of Great Salt Lake. H. 



Montgomery 77 



Nature's Rotation of Crops. . M. W.' V.! ! ! ! ! ! 78 

 Worms on the Brain of a Bird. S. H. Scud- 



der , 78 



A Space-relation of Numbers. D. S. Mar- 



„tiiL 78 



Prehmmary Note on the Cottony Scale of 



the Osage Orange. T. D. A. Cockerell. 7S 



Explosive Gas in Hot Water Apparatus. A. 



H. MacKay 70 



Mineral Wax. H. Monteromery ' 70 



Animal Vocabularies. C. B. Palmer 80 



A Maya Month-name— Khmers. D. G. Brin- 



ton 80 



Theory of Color Sensation. C. L. Franklin. 80 

 Current Notes on Anthropology.— NoXXXII. 



D. G. Brinton, Editor Sj 



Note on Crotalus Adamanteus. P. H. Rolfs....! 82 

 Book Reviews go 



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NEW METHOD OF PROTEGTIHG BUILDINGS FROM LIGHTNING. 



SPARE THE ROD AMD SPOIL THE HOUSE! 



Lightning Destroys. Shall it be Your Souse or a Pound of Copper? 



PROTECTION FROM LIGHTNING. 



What is the Problem ? 



In seeking a means of protection from lightning-discharges, we have in view 

 two objects,— the one the prevention of damage to buili:llngs, 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 1p, as physicists express 

 It, energy Is required. Just before the llghtnlug-dlsonarge takes plaiie, 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. What this electrical energy is, it is not necessary for us to 

 consider In this place ; but that It esists there can be no doubt, aa it manifests 

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

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

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

 erty and life. 



Why Have the Old Rods Failed? 



When Ughtnlng-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 tact that the different forms of energy — 

 heat, 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 of the conservation and correlation of energy was first 

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

 some facts known in regard to electricity a hundred and forty years ago; and 

 among these were the attracting 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 

 building would thus be saved. 



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

 naturally; and from that time to this, in sttlte of the best endeav6rs of thnse 

 Interested, lightning-rods constructed i'l accordance with Franklin's principle 

 have not furnished satisfactory protection. The reason for this i-* appar nt 

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

 before the discharge, or, more exacilr, iu the column of dieleclrto from the 

 cloud to the earth, above referred to, reaches its maximum valu'^ on the sur- 

 face of the conductors that chance to be within the coiutnn of dlel-^ctric; so 

 that the greatest display of energy will be ou the surface of the very ligbtning- 

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

 the case. 



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

 of the old lightning-rods is aided by their being more or L-ss insulated from 

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

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

 energy upon its surface, — " to draw the lightning," as it Is so commo/tly put. 



Is there a Better Means of Protection? 



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

 and keeping cle^irly invlew the tact that in providing protection against light- 

 ning we must furnish some me^us by which the electrical energy may be 

 harmlessly dissipated, the question arises, " Can an Improved form be given 

 to the rod so that It shall a'd In this dissipation ? " 



A3 the electrical energy involved manifests itself on the surface of conduc- 

 tors, the Improved rod should be metallic; but, Instead of makiug a large rod, 

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

 of metal running from the top of the house to some 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 —when a 

 discharge takes place; an 1 it will be evident, that, so far as tbe electrical en- 

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



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 tend to injure other 

 bodies in its immediate vicinity. On this point I can only say that X have 

 found no ease 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 which the conductor rests may be stained, but they are not shattered, 



I would therefore make clear this distinction 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 dissipated conductor. 

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

 as to resist the explosive effect, — 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 Collinson read before the Loudon Eoyal Society, 

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

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

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

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

 like maimer; then horizontally under and ne.ar the plastered ceiling of that 

 second floor, till it camenear a plastered wall; then down by the sideotthat 

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

 not bigger than a common knitting needle. The spire was split all to pieces 

 by the lightning, and the parts flung In all directions over the square In whhh 

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

 passed between the hammer and the clock In the above-mentioned wire 

 without hurting either of the floors, or having any effect upon them (except 

 making the gimlet-holes, through which the wire passed, a little bigger), ond 

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

 aforesaid wire and the pendulum-wire of the clock extended ; which latter 

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

 lum, down quite to the ground, the building was exceedingly rent and dam- 

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

 aud the hammrr, 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 it3 particles dissipated in smoke and air. as gun- 

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

 ti< log, three or four inches broad, darkest in the middle, and fainter towards 

 the edges, all along the celling, under which it passed, aud dovn the wall. ' 



One hundred feet of the Hodges Patent Lightning Dtspellrr (male under 

 pateuts of N. D. C. Hodges, Editor of Science) wlU be mailed, postpaid, to any 

 r.ddress, ou receipt of five dollars ($5). 



Correspondence lollcited. Agents wanted. 



AMERICAN LIGHTNING PROTECTION CO., 



874r Broadwaj^, ]Sre\v York Citv. 



