\ 



Eleventh Year. 

 Vol. XXII. No. 565. 



DECEMBER 1, 1893. 



Single Copies, Ten Cents. 

 I3. 50 Per Year, in Advance. 



CONTEN TS 



Review of the Birtli of the Great Lakes and 



Their Deserted Shores 295 



Texas Clays and Their Origin, W. Kennedy. 297 

 Karyokinesis in Embryos of the Domestic Cat. 



—Preliminary Notice. FrankS. Aby 300 



The Pterylography of the Pileated Woodpecker 



Hubert Lyman Clark 302 



Secret Language of Children. Oscar Chrisman 303 

 Parasitism of Molothrus Ater. Chas. W. Har- 



gitt :.... 30s 



Letters to the Editor, 



An Intelligent Squirrel. Ray Greene Rul- 

 ing 306 



St. Louis Limestone in Poweshiek County, 

 Iowa, Arthur J. Jones 307 



Scientific Instruments i 



OF STANDARD QUALITY: I 



s^ Physical, Electrical, Chemical, Optical, Microscopical, En- ^ 



g gineering, Mathematical, Photographic and Projection Ap- ^ 



g paratus and Supplies. Special care devoted to the equipment p 



g of College and High School laboratories. Estimates submit- $ 



$ ted upon request. S 



g Correspondence solicited. a 



g Write for abridged General Catalogue No, 219, S 



I OUEEN & CO., Incorporated, I 



I Philadelphia, U. S. A. I 



S Eight Awards granted us at the World's Fan-. }S 



Newr store. 

 IVew Stock. 

 Nenr Departments. _ 



Send for our " Winter Bulletin," recently issued. , tureVis'lilgHly recommended by college professors 

 Minerals, Gems, Microscopical Sectiona, Fine Lap- ""'' *''° "'«'■■= »= '* " ""* = "-^ "<>* "- = .10 



idary Work. 



GEO. L. ENGLISH & CO., Mineralogists, 



Removed to 64 East 12th Street, New York 



fPETDMAMIA ^ monthly magazine for the study 

 «• ' ULnmnillH of the German language and litera- 

 ture, is highly recommended by college professors 

 and the press as "the best effort yet made to assist 

 the student of German, and to interest him in his 



I pursuit. '' Its Beginners' Corner furnishes every 

 year a complete and interesting course in German 

 grammar. gS a year. Single copies 20 cents, P. O. 

 (Box 151, Manchester. N. H. 



HEW METHOD OF EROTECTIHG BUILDINGS FROM LIGHTNING. 

 SPARE THE ROD AND SPOIL THE HOUSE! 



Tdightning Hestroys, Shall it be Your House or a Found of Copper? 



PROTECTION FROM LIGHTNING. 



What is the Problem? 



In seeking a means of protection froai lighruiag-discharges, wo have In view 

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

 the prevention of injury to life. In order to destroy a building lu whole or in 

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

 It, energy is required. Just befora the lightning-discharge takes plaje, 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 wo 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 thatlteslsts there can be no doubt, as it manifests 

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

 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 In] ury 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 fact 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 o( 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 attractlrg power of points for an electric spark, and the 

 conducting power of melals. Lightning-rods were therefore introduced with 

 the Idea that the electricity existing In the lightning-discharge could be cou- 

 Toyed 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 those 

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

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

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

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

 cloud to the earth, above referred to, reaches Its maximum value on the su.*"- 

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

 that the greatest display of energy will be on I he surface of the very llgbtulng- 

 roda that were meant to protect, and damage results, as so often pro"*i3 to be 

 the case. 



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

 of the old lightning-rods Is aided by Iheir being more or if si Insulated from 

 the earth, but In any event the very existence of suc^a a mass of metal as an 

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

 energy upon Its surface,— " to draw the llgljtnlng," as It is so commonly put. 



Is there a Better Means cf Protection ? 

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

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

 ning we must furnish some means 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. ii this dissipation? " 



As the electrical energy Involved manifests Itself on the surface ot conduo- 

 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 toial 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; 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 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 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. 



Ot course, it is readily understood that such an explosion cannot take place 

 In a confined space without the rupture of the walla (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 Colllnson read before the London 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 tall ot the hammer a wire went down through a small 

 gimlet-hole In the floor 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, till it came near a plastered wall ; then down by the side ol that 

 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 piece* 

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

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

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

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

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

 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 thicliuess of a goose-qnlU. From the end of the pendu- 

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

 aged. . . . No part of the aforementlontd long, small wire, between the clock 

 and the ham"aer,oould be ."ound, except about two Inches that hung to the 

 tai'oft'de 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 commou flre, and had only left a black smutty track on the pla.".- 

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

 tt>.e edges, »U along the ceiling, under which it pasied. and down the wall." 



0".e hundred feet of the Hodges Patent Lightning Dispeller (made under 

 patents of N. D. C. Hodges. Editor of Scienct} will bo nailed, postpaid, to any 

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



Correspondence solicited. Agents u-anted. 



AMERICAN LIGHTNING PROTECTION CO., 



87-4 Broadway, New York Citv. 



