VA 



NCE 



UBRARV 



Eleventh Year. 

 Vol. XXII. No. 553. 



SEPTEMBEE 8, 1893. 



Single Copies, Ten Cents. 

 S3. 50 Per Year, in Advance. 



Contents 



The Marine Biological Laboratory. Dallas L. 



Sharp 



How Chemistry Is Best Taught. Charles F. 



Mabery 



Notes on the Wood or Fallow Ant of Southeast- 

 ern Massachusetts. J. B. Wood worth 



Problems of Zoology. Dr. C. V. Riley 



Letters to the Editor. 



Red Birds and a Grosbeak. J. McNair 



Wright 



Space Relation of Numbers. Talcott Wil- 

 liams 



Columbian Congresses on Science and Phi- 

 losophy. X 



Palenque Hieroglyphics. Cyrus Thomas. . 



Color Vision. Christine Ladd Franklin .... 



Myology of the Cat; or the M. Flexor Acces- 



sorius of tile Human and Feline Foot. 



Howard Ayres 



Damage to Cotton by Lightning. Frank E. 



Emery 



On Some Nesting Habits of the Amer'can 



Goldfinch. Paul Van Riper 



Physical Chemistry at the Columbian Con 



gress. Robert B. Warder 



Great Horned Owls in Confinement. Wil- 



lard E. Treat 



Book Reviews 



Acme No, 



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NEW METHOD OF PROTECTIHG BDILDINGS FROM LIGHTNING. 

 SPARE THE ROD AMD SPOIL THE HOUSE! 



Idightning Destroys. Shall It be Tour Hon 



; Pound of Copper ? 



PROTECTION FROM LIGHTNING. 



What is the Problem? 



In seekingameansof protection from lighiuia^-discharges, we have in view 

 two objects,— the one the prevention of damage to builolnga, and the other 

 the prevention of luxury to life. In order to destroy a building In wholf or in 

 part, It is necessary thai work, should be done ; that is, as physicists exi rees 

 It, energy Is required, Ju^^t before ihe lighmiug-dlscharge takes piaje, the 

 energy capable of doing the damage which we seek to prevent exltta 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 ihls electrical energy is, it is not necessary for iis 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 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 rebult in the least injury to prop- 

 erty and life. 



Why Have the Old Rods Failed ? 



■When lightning-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 other, 

 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 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 meials. 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 spite of the best endeavors of ih se 

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

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

 when it is considered that the electrical energy existing !n 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 tae very lightning- 

 rods that were meant to protect, and damage result.?, as so often proves to be 

 the case. 



It will be understood, of course, that this di-play of eaprgy on the surface 

 of the old lightning-rods is aided by their being more or 1 ss 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 ligbtulng," as It is so commonly put. 



Is there a Better Means of Protection? 



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

 and keeping clearly in view the fact that iu providing protection against light- 

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

 harmlessly dissipated, the question ari-ses, ** Can an improved form be given 

 to the rod so that It shall aid In this d'3?ip.'it!o:: ? " 



As the electrical energy Involved manifests Itself on the surface of conduc- 

 tors, the Improved rod should be meLalllc ; but, instead of makiug a large rod, 

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

 of inelal running from the top of the house to some point a little below the 

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

 numerous Insulating Joints iu this rod. We shall then have a ro 1 that experi- 

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

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

 ergy is consumed in doiug 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 disslpaiion of such a conductor d<"^-i not t'-nd to injure other 

 bodies In ics immediate vicinity. On this poin . I caa only say that 1 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 cour-e, it is r* adUy understood that such an explosion cannot take place 

 in a ciiifiu'^d space wiLh"Ut the rupture of the walls (the wire cannot be 

 boarded over); but in every case that I have fouud recorded this dissipation 

 takes Uace j'lst as gunpowder burns when spread on aboard. The objects 

 against w irh the Ci>nductor rests may be stained, but they are not shattered, 



I wo .Id theretoremalie clear thl3 distinction between the action of eUctrl- 

 '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 effecr, — 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. 



Franklli', inaletter to CoUInson read before the London Royal 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 tall of the hammer a wire went down through a small 

 gimlet-hole In the fl,oor that the bell stood upon, and through a second floor m 

 like manner; then horizontally under and near the plastered celling of that 

 second floor, tUl it came near a plastered wall; then down by the side oi that 

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

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

 by the lightning, and the parts fluug in all directions over the square In whUh 

 the church stood, so that nothiDg remained above the bell. The llgbtrirg 

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

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

 making the gimlet- holes, through wh'ch the wire passed, a little bigger), and 

 wltliouc 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 ih^ thickness of a gOii.-^e-quiU. From the end of the pendu- 

 lum, down q'lite to the ground, the bail un? was exceedingly rent and dam- 

 aged. . . . No p'lrt of the aforementioned ling, small wire, between the clock 

 audthe hammer, could bo found, except about two inches that hung to the 

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

 rest being exploded, and Its particles dissipated In smoke and air. as gun- 

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

 teiiug, three or four inches broad, darkest in the mlddl**, and fainter towards 

 the edges, all along the celling, under which it passed, and down the wall. ' 



One hundred feet of the Hodges Patent Lightning DIspeller (made under 

 patents of N. D. C. Hodges, Editor of Scieiice) will be mailed, postpaid, to any 

 address, on receipt of five dollars ($5). 



Correspondence ■solicited. Agents wanted. 



AMERICAN LTGHTiVIN(J PROTECTION CO. 



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