Finally, the writer wishes to state that he is not prepared, nor does he desire, to write a final treatise on the Tucumcari, which can never be properly related until the atlas-sheets of the United States Geological Survey are completed for the region. Tucumcari is but a single station in the vast group of phenomena belonging to the deposition and degradation of the Las Vegas and Llano Estacado Plateaus and the Canadian Valley, and to be properly understood, it would be necessary to write a treatise on the whole region. One thing is settled beyond all doubt in my mind, however, and that is that the G. dilatata beds of the region do not belong to the Jurassic, but are undoubtedly of Cretaceous age. On the other hand, it may also be safely assumed that the Gryphœa dilatata, Sow., of Marcou, is not the same as G. pitcheri, Morton, as has been asserted by many authors, nor does it occur in the Cretaceous beds of central Texas, so far as the writer is aware. But this is a question which cannot be discussed intelligibly until a thorough revision of the Gryphæas is made. In conclusion, permit me to say that there is not one trace of the Jurassic formation over the Texas region, as Mr. Marcou so positively affirms, and, furthermore, that there is no evidence that it was ever there, the whole trend of the testimony being to show that that region was land during the Jurassic period. If the writer should devote his time to criticising the works of his contemporaries or predecessors, he would have little time for research. It has been my practice, however, under the opinion that all knowledge is progressive, to see the good in the works of others, and to correct any errors without abuse. In all I have published on the Texas region, there is not a line which was written with the desire to discredit any man, and yet I believe that my severest critics will confess that there has been great advance in opinion since I undertook the renaissance of geologic study in Texas. My collections from Tucumcari are in Washington, and are -open to the inspection of anyone inter sted. ROBT. T. HILL. Chloropia. THE case of Wallian, reported on page 360 of the latest volume of Science, would seem to be one of temporary Chloropia. More extended and carefully recorded observations, while the observer is looking at various objects under various conditions, would be very desirable. E. W. SCRIPTURE. Yale University, New Haven. Trees as a Factor in Climate. I ONCE observed a signal case of the effect of trees in determining rainfall. A few years ago I was walking along a road in the so-called backbone of England at an elevation of from 800 to 1,000 feet above the sea level. It was a dull, calm October day, and the hills on either side were cased in mist. Where I was no rain was falling and the ground was quite dry. As I passed on the road entered and traversed a wood of fir trees. Here I at once encountered a gentle drizzle. Far from suspecting that the trees were playing any part in the matter, I concluded that the expected wet weather had at last set in. When the road emerged from the wood at its opposite extremity I found that no rain was there falling or had fallen. Still I did not connect the trees with the downfall, but imagined that the weather had again improved. On returning from my destination about three hours after wards I found that the rain was still falling in the wood, but that it ceased as soon as I emerged into the open country. The ground, too, within the wood was wet, still all around it was dry. Hence it appeared that a slight rain must have been falling for the greater part of the day within the wood, but not in the bare fields and heath land outside. Thus under certain conditions of the weather the presence of trees may determine rainfall which would not take place in their absence. J. W. SLATER. London, England. Mineral Wax. I notice an account and inquiry in Science of June 16 in regard to the receipt at the National Museum of specimens of natural wax coming from Portland, Oregon, derived from the shores of the Columbia River, and from other accounts it is found along the coast from the Columbia River to Puget's Sound. The material has been well known for the past half century as mineral wax, native paraffin, ozokerite and lastly as ozocerite, a hydrc-carbon compound (hydrogen, 15 per cent; carbon, 85 per cent variable); supposed to be derived from bituminous and lignite coal formation by infiltration and crystallization. It is generally found in situ in the neighborhood of coal and lignite beds and in the bituminous clays or shales. The legend as to its being derived from a wreck is a most absurd one. It is a resinous wax in consistency and translucency, with structure sometimes foliated; color brown or yellowishbrown by transmitted light; leek green by reflected light; odor, aromatic, in specimens that I bave examined, having the characteristics and feel of beeswax that had been lying for some time in water. It is mined in variable quantities in Germany, Austria, Turkey, and England, associated with the soft coal and lignite beds. In Galicia alone about 30,000 tons have been mined since its discovery there in 1859. It is used in Europe principally in the manufacture of candles and by refining in place of beeswax and paraffin. It is said to be an excellent electrical insulator. In the United States it is mined in situ at Soldiers Summit, Uintah County, and in Emery County, Utah. Sixty-five thousand pounds were marketed in 1888, with a yearly increasing output. The whole product of the United States in 1890, including the Oregon find, reached 350,000 pounds. The imports of mineral wax, ozocerite, under the names of bay or myrtle, Brazilian and Chinese wax, in 1890 were over one and a half million pounds. It has been found in situ in thin seams in the lignite beds of Oregon, Washington, and British Columbia. The deposits along the Columbia River and on the sea-shore of Oregon are no doubt the debris from lignite beds near by. C. D. HISCOX. 361 Broadway, New York. BOOK-REVIEWS. The Seismological Journal of Japan. Edited by JOHN MILNE, F.R.S. IN 1880 the Seismological Society of Japan was founded by a number of earnest students of seismology in that country, prominent amongst whom was the editor of this Journal. In the earlier years of its existence iis membership included such well-known names as Milne, Gray, Ewing, Mendenhall and others at that time resident in Japan, and their interest in the science led especially to the invention of many instrumental appliances for the study of earthquake phenomena, some of which have been copied wherever earthquakes are observed, and in some respects have revolutionized the science of experimental seismology. It also resulted in the establishment of a chair of seismology in the Imperial University of Japan, and the organization of a bureau controlling a central observatory and some 700 outside stations. Of late years, however, the interest in the society has declined, partly through the return of some of its most active supporters to England and America, and, after publishing sixteen volumes of Transactions, in 1892 the society ceased to exist. Professor Milne, however, still remains in Japan and has determined to continue the publication of seismological literature in the present journal, which is therefore to be regarded, not as an entirely new venture, but as a continuation of the series heretofore known as the Transactions of the Seismological Society. The new journal is issued in the same form and from the same printers as the old Transactions, and the first number, now at hand, bears on its title page Vol. XVII, which is its number in the old series, so that the new volumes can be bound uniformly with those previously issued. The annual subscription is five dollars. In this number the first article is on The Mitigation of Earth quake Effects and Certain Experiments in Earth Physics" by Professor Milne, in which various lines of experiment are proposed that might possibly lead to the prediction of severe earthquakes so as to guard against their effects. In the second, "On the Application of Photography to Seismology and Volcanic Phenomena," Professor W. K. Burton describes with illustrations the photographic records from Milne's temor indicators. In the third Professor Milne gives an abstract of the "Seismometrical Observations for the Year 1890," from which it appears that in that year 845 earthquakes were felt in Japan, of which 49 were classed as severe, 264 as moderate and 532 as feeble. Of the severe earthquakes, four (Jan. 7, Mar. 19, Apr. 16, Nov. 17) were accorded more detailed description. In the fourth article "On the Overturning and Fracturing of Brick and other Columns, by Horizontally Applied Motion," Professor Milne and F. Omori describe a very interesting series of experiments, wherein various objects such as blocks of wood of different dimensions, bricks, columns built of brick or of cement, were mounted on a wheeled truck to which a reciprocating horizontal motion could be communicated, and the circumstances of the motion, with the overturning or fracture of the object, were electrically recorded. From the data the maximum velocity and maximum accelleration necessary for overturning were calculated and compared with the experimental results with a fairly good agreement. In an article on "Earth Pulsations in Regard to Certain Natural Phenomena and Physical Investigations," Professor Milne concludes that the movements called earth tremors are move ments in the crust of the earth not altogether unlike the swell Notions de Chimie Agricole. Par TH. SCHLOESING, FILS. Paris, THE MODERN MALADY; or, Suf- Pennsylvania Bedford Springs Mineral Water ferers from 'Nerves.' An introduction to public consideration, from a non-medical point of view, of a condition of ill-health which is increasingly prevalent in all ranks of society. In the RESTORE YOUR EYESIGHT first part of this work the author dwells on Cataracts, scars or films can be absorbed and paralyzed nerves restored, without the knife or risk. Diseased eyes or lids can be cured by our home treatment. "We prove it." Hundreds convinced. Our illustrated pamphlet, Home Treatment for Eyes," free. Don't miss it. Everybody wants it. "THE EYE," Glens Falls, N.Y. WORLD-ENGLISH. 25 Cents. HANDBOOK OF 25 Cents. Ex President Andrew D. White, of Cornell University, says: "I believe thatthe highest interests of Christian civilization and of humanity would be served by its adoption." "So set down, our tongue is the best for the world to unite upon."-Brooklyn Eagle. "The idea of Mr. Bell has much to recommend it, and the presentation is charmingly clear."-Ameri can, Phila. "The result is a language which cannot fail to meet with acceptance."-Boston Traveller. "World English deserves the careful consideration of all serious scholars."-Modern Language Notes. Sent, postpaid, on receipt of price. N. D. C. HODGES, 874 Broadway, N. Y. For Liver, Kidney and Bladder Troubles. It has been used medicinally and prescribed by Case One Dozen Half-Gallon Bottles, $4.50. Philadelphia Office, 1004 Walnut St. $25 to $50 the errors in our mode of treating Neuras- Bedford Mineral Springs Co., Bedford, Pa. per week, to Agents, Ladies or Gentlemen, using or selling "Old Reliable Plater." Only practical way to replate rusty and worn knives, forks, spoons, ete; quickly done by dipping in melted metal. No experience, polishing or machinery. Thick plate at one operation; lasts 5 to 10 years; fine finish when taken from the plater. Every family has plating to do. Plater sells readily. Profits large. W. P. Harrison & Co., Columbus,0. New Store. New Departments. Send for our "Winter Bulletin," recently issued. Minerals, Gems, Microscopical Sections, Fine Lapidary Work. GEO. L. ENGLISH & CO., Mineralogists, Removed to 64 East 12th Street, New York ABOUT.@. MAGIC LANTERNS ASK US +C-WE MAKE THEM. J.B.COLT & CO. 16 BEEKMAN ST., 189 LA SALLE ST NEW YORK CHICAGO.I to plant life. Methods of chemical analysis are wisely left for a separate work and the results of analysis alone are given when a knowledge of the same is necessary to an understanding of the discussion. The nature of the experiments, however, and the manipulation of the same, are given with sufficient fullness to enable the reader to judge of the value of the conclusions, The general arrangement of the book is as follows: Part I. treats of the nutrition of plants, of germination, and of the origin of the organic and inorganic constituents. Part II. makes a study of the atmosphere in its relation to plant life and of the gases influencing this life, of nitrogen, oxygen, carbonic acid, nitric acid, ammonia, etc. Part III. treats of soils, their formation and composition, and of their physical and chemical properties. bibliography, coinciding with the arrangement of the text, completes the work. A The author is particularly interesting in his section on nitrification and also in treating of the assimilation of free atmospheric nitrogen by plants and soils. The experiments and conclusions of Berthelot and André are noted as well as those of M. Schloesing, the author concluding with; "Il n'entre pas dans notre programme d'insister davantage sur ces diverses recherches; car nous tentons d'ordinaire à n'avancer que des faits positifs. Ici il ne nous est guère permis de faire un choix entre les opinions produites. Il est à espérer qu'un prochaine avenir levera les doutes qui règnent encore sur ce grave sujet." The book has the usual exquisite neatness of first-class French publications, with full-bodied paper, clear print and broad margins, making it altogether a most enjoyable volume. CHARLES PLATT. Outlines of Forestry, or the Elementary Principles Underlying the Science of Forestry. By EDWIN J. HOUSTON. Philadelphia, J. B. Lippincott Co. 254 p. 12°. $1. THIS little book is a useful manual of facts relating to the subject. Among the matters considered are the conditions necessary for the growth of plants, distribution over the earth, forma Delicious Drink. Horsford's Acid Phosphate with water and sugar only, makes a delicious, healthful and invigorating drink. tion of soil, animate and inanimate enemies of the forest, vapor, rain, drainage, climate, hail, reforestation and tree planting, etc. The last chapter, called "Primer of primers," contains in short, concise sentences the substance of what had been given at length in the earlier chapters. Taken by itself, it would serve a useful purpose in the education of the general public to the importance of the subject. The book is, perhaps, unfortunately written in a loose and rather slovenly manner. It abounds in repetitions of not only the same ideas, but also of nearly identical words. The following extracts are particularly bad examples, but they fairly represent the ordinary style of the writer: "Heat and light are to be found in practically all parts of the earth. They differ, however, in amount in different regions of the earth, and such differences cause the differences that are noticed in the plants that grow in different regions " "The quantity of moisture in the air differs greatly in different parts of the earth, and on this difference, together with the difference in temperature, depends the differences observed in the plants of various regions.' "Each section of the country possesses, so to speak, a nationality in its plants, or, in other words, there lives in each section of country a particular nation of plants. Such a nation of plants, or the plants peculiar to a particular section of country, is called its flora." The author makes use of a new word, "heatshine," which is rather difficult to define. "The sunshine and the heatshine which awaken the sleeping germ and call it into activity," etc. In the appendix are given various lists of trees suitable for planting, and these contain some curious errors. For example, under the head of "deciduous trees" we find maples, hickories, cedars firs and pines, while under "evergreens" are placed spruce, larch, sweet gum poplar, oak, walnut, etc. In another place we observe under "conifers" bald cypress, red cedar, white pine, black cherry and European alder, while the European larch figures in another table as an evergreeen. Errors of this kird rather detract from the value of the book. JOSEPH F. JAMES. Wants. AYOUNG man who his periferous University, in mathematics in Princeton wishes some tutoring this summer. Rates reasonable. Address P. H Westcott, Cramer's Hill, Camden Co., N. J. A GRADUATE of an American Polytechnic institution and of a German university (Göttingen), seeks a position to teach chemistry in a college or similar institution. Five years' experience in teaching chemistry, Address Chemist, 757 Cary St, Brockton, Mass. experienced teacher in general biology wist es a position in a first-class college or university. Three years in post-graduate study. Extensive experience. Strong indorsements. Address E. W. and works on Ethnology. F. A. Hassler, M.D., Doran, Ph.D., 1327 & St., N. W., Washington, D. C. I have a fire-proof safe. weight 1,10 pounds, which I will sell cheap or exchange for a gasoline safe new, used short time Allays the thirst, aids diges-eng The sure is hently new, at may happen to tion, and relieves the lassitude only. Make offers. A. Lagerstrom, Cannon Falls, so common in midsummer. is Minn., Box 857. For exchange.-Hudson River fossils in good con- fenses, four inches diameter, made by C. C. Harri. W school, a gentleman of education and experi Dr. M. H. Henry, New York, says: "When completely tired out by proFor sale at low price.-A fine old-fashioned photographic camera, rosewood box, one foot square, longed wakefulness and overwork, it son. Plateholders, troughs, baths, etc., all in large of the greatest value to me. As a bev- wooden case, formerly the property of the late President Moore, of Columbia College. This is a erage it possesses charms beyond any-fine example of an instrument of the best make for the old wet-process methods, and valuable to any thing I know of in the form of medi-institution or amateur interested in the history of photography in the U. S. Address M. S. Daniel, cine." 236 W. 4th St., New York. Descriptive pamphlet free. Rumford Chemical Works, Providence, R. I. Beware of Substitutes and Imitations. I wish to exchange a collection of 7,000 shells, 1001 species and varieties, American and foreign, land, fluviatile and marine, for a good microscope Lorenzo G. Yates, Santa Barbara, California. and accessories. Address, with particulars, Dr. For exchange.-I wish to exchange Lepidoptera of South Dakota and other sections, for Lepidoptera of the world. Will purchase species of North America. Correspondence solicited, particularly with collectors in the Rocky Mountains, Pacific coast and Hudson's Bay regions. P. C. Truman, Volga, Brooking county, South Dakota. ANTED, as principal of a flourishing technical ence who will be capable of supervising both mechanical and common school instruction. Special familiarity with some technical branch desirable. Address, giving age, qualifications, etc., J. B. Bloomingdale. Fifty-ninth street and Third avenue, N. Y THE American Bell Telephone COMPANY. 125 MILK ST., BOSTON, MASS. This Company owns the Letters - Patent No. 186,787, granted to Alexander Graham Bell, January 30th, 1877, the scope of which has been defined by the Supreme Court of the United States in the following terms: "The patent itself is for the mechanical LIGHTNING DESTROYS! Shall it be your house or a pound of copper? Entirely new departure in pro tecting buildings from lightning. QUERY. Can any reader of Science cite a case of lightning stroke in which the dissipation of a small conductor (one-sixteenth of an inch in diameter, say,) has failed One hundred feet of the Hodges to protect between two horizonPatent Lightning Dispeller tal planes passing through its structure of an electric telephone to be used (made under patents of N. D. C. upper and lower ends respective to produce the electrical action on which the first patent rests. The third claim is for the Hodges, Editor of Science) will ly? Plenty of cases have been use in such instruments of a diaphragm, made of a plate of iron or steel, or other ma terial capable of inductive action; the fifth, be sent, prepaid, to any ad of a permanent magnet constructed as de scribed with a coil upon the end or ends dress, on receipt of five dollars. nearest the plate; the sixth, of a sounding box as described; the seventh, of a speaking or hearing tube as described for conveying the sounds; and the eighth, of a permanent magnet and plate combined. The claim is not for these several things in and of them Correspondence solicited. Agents wanted. found which show that when the conductor is dissipated the building is not injured to the extent explained (for many of these see volumes of Philosophical Trans selves, but for an electric telephone in the AMERICAN LIGHTNING PROTECTION CO., actions at the time when light construction of which these things or any of them are used." This Company also owns Letters-Patent No. 463,569, granted to Emile Berliner, No 874 Broadway, New York City. ning was attracting the attention of the Royal Society), but not vember 17, 1891, for a combined Telegraph Fact and Theory Papers an exception is yet known, al and Telephone, and controls Letters-Patent No. 474,231, granted to Thomas A. Edison, though this query has been pubMay 3, 1892, for a Speaking Telegraph, I. THE SUPPRESSION OF CONwhich cover fundamental inventions and lished far and wide SUMPTION. By GODFREY W. HAMBLETON, M.D. embrace all forms of microphone transmitters and of carbon telephones. BUSINESS OPPORTUNITY. There is an opening for a young man to open a New York office of the American Lightning Protection Co., operating under my patents. But little capital will be required. N. D. C. HODGES, 874 BROADWAY, NEW YORK INDEX TO VOLUME XVIII OF SCIENCE is in preparation, and will be issued at an early date. N. D. C. HODGES, 874 Broadway, New York, N, Y. IV. THE CHEROKEES IN PRE-CON. D. C. HODGES, 874 BROADWAY, N. Y. CAL CULTURE CHART, with illustrated directions for developing every part of the body healthfully, 50 cts. Sent for half price to those naming this paper. WHITNEY HOME GYMNASIUM CO., Box D., Rochester, N. Y. JULY 21, 1893. Walker Prizes in Natural History. The Boston Society of Natural History offers a first prize of from $60 to $100 and a second prize of a sum not exceeding $50 for the best memoirs, in English, on one of the following subjects: 1. The relations of inflorescence to cross-fertiliza. tion illustrated by the plants of Eastern Massa, chusetts. 2. What depths of formerly overlying rocks, now removed by denudation, may be inferred from the structure of various rocks in Eastern Massachusetts ? USEFUL HAND-BOOK. The Ornamental Penman's Pocketbook of Alphabets, for sign-writers, engravers, stone-cutters and draftsmen, 20 cts. A System of Easy Lettering, by Howard Cromwell, 50 cts. Practical Electrics: A Universal Handybook on Every-day Electrical Matters, 135 pp., fully illustrated, 12mo, cloth, 75 cts. Notes on Design of Small Dynamo, by G. Halliday, 79 pp., with a number of plates to scale, 12mo, cloth, $1. The Phonograph and How to Construct It, by W. Gillett, 87 pp., 12 folding plates, 12mo, cloth, $2. SPON & CHAMBERLAIN, Publishers, 12 Cortlandt St., New York. Illustrated and descriptive catalogues, 10 cts. The Batrachians and Reptiles of Indiana. 3. Experiments affording evidence for or against species of Batrachians and Reptiles, together with the theory of evolution. Each memoir must be accompanied by a sealed envelope enclosing the author's name and superscribed by a motto corresponding to one borne by the manuscript, and must be handed to the Secretary on or before April 1, 1894. Prizes will not be awarded unless the memoirs are of adequate merit. SAMUEL HENSHAW, Secretary. Boston, July 3, 1893. NEW METHOD OF PROTECTING BUILDINGS FROM LIGHTNING. SPARE THE ROD AND SPOIL THE HOUSE! Lightning Destroys. Shall it be Your House 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 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 required. Just before the lightning-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. What 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 deal with, therefore, is the conversion of this energy into some other form, and the accomplishment of this in such a way as shall result in the least injury to property and life. Why Have the Old Rods Failed? When lightning-rods were first proposed, the science of energetics was entirely 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 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 conveyed 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 in 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, in the column of dielectric from the cloud to the earth, above referred to, reaches its maximum value on the surface 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 lightningrods 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 less insulated from the earth, but in any event the very existence of such 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 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 against lightning 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 aid in this dissipation?" A Work of 204 pages, with 3 plates of 12 figures. Contains full descriptions of nearly one hundred 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, postpaid. $1.00. Bowen-Merrill Book Co, Indianapolis, Ind. GERMANIA A monthly magazine for the study of the German language and literature, 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 pursuit." Its BEGINNERS' CORNER furnishes every year a complete and interesting course in German grammar. $2 a year. Single copies 20 cents. P. O. Box 151, Manchester, N. H. As the electrical energy involved manifests itself on the surface of conductors, 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 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 experlence 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 energy 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 dissipated, 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 electrical energy when dissipated on the surface of a large conductor and when dissipated 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 London Royal Society, Dec. 18, 1755, describing the partial destruction by lightuing of a church-tower at Newbury, Mass, wrote, "Near the bell was fixed au iron hammer to strike the hours; and from the tall of the hammer a wire went down through a small gimlet-hole in the floor that the bell stood upon, and through a secoud floor in like manner; then horizontally under and near the plastered celling 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 knitting needle. The spire was split all to pieces by the lightning, and the parts fluug in all directions over the square in which the church stood, so that nothing remained above the bell. The lightring 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 littl bigger), and 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-qu'll. From the end of the pendulum, down quite to the ground, the building was exceedingly rent and damaged. No part 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 its particles dissipated in smoke and air, as gunpowder is by common fire, and had only left a black smutty track on the plastering, three or four inches broad, darkest in the middle, and fainter towards the edges, all along the ceiling, 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 Science) will be malled, pos:paid, to any address, on receipt of five dollars ($5). Correspondence solicited. Agents wanted. AMERICAN LIGHTNING PROTECTION CO., 874 Broadway, New York Citv. |