May 5, 1893.J 



SCIENCE. 



251 



Introduction A la Thiorie des Explosifs. Par M. E. Sarkau, Inge- 

 nieur en Chef des Poudres et Salpetres, Membre de I'lnstitut. 

 Paris, Qauthier-Villars et Fils, 1893. 115 p. 

 To the student of applied and theoretical mathematics this work 

 of the eminent M. E. Sarrau will be most welcome. Unfortunately 

 our language can boast of but little on the mathematical theory 

 of explosives, and that little mainly in isolated chapter's, imper- 

 fect and confusing in their briefness. Whether this be due to 

 lacli of interest or of study, we do not care to discuss, but certain 

 it is that for a clear exposition of mathematical thought we must 

 turn to writers of other lands than ours. From France we have 

 received many of our best works, and it is with pleasure that we 

 now announce this new work from the hand of M. E. Sarrau. A 

 prefatoi'y note, four lines in all, states the author's intention to 

 bring forward such mechanical, thermo-chemical, and thermo- 

 dynamical problems as are necessary to a comprehensive theory 

 of explosives. Throughout, the discussion, which is both ana- 

 lytical and general, is so clearly and concisely accomplished as to 

 be quite within the understanding of any student versed in dif- 

 ferential and integral calculus. The first chapter treats analyti- 

 cally of the mechanical principles, including work, kinetic energy, 

 and potential energy. In the second chapter are established the 

 general laws of gases. Marietta's, Gay-Lussac's, the law of specific 

 volume, the hypotheses of Avogadro and of Ampere, the molec- 

 ular and atomic weights, the melecular volumes, and the chemi- 

 cal formulae. In this same chapter are studied the laws governing 

 the specific heat of gases and the laws of gaseous mixtures. 

 Chapter III. treats of the thermo-dynamics of perfect gases, and 

 Chapter IV. of the general principles of thermo-dynamics, in- 

 cluding thermal phenomena, equivalence, and the principle of 

 Carnot-Clausius. Chapter V. is devoted to liquids, the law of 

 compression, and the equations of Van der Waals and Clausius. 

 The preceding theories and principles are applied in Chapter VI. 

 to the various transformations, first without change in physical 

 state and then with change from one state (of pressure, tempera- 



ture, and volume) into another. The nature of heat is discussed 

 in Chapter VII., and the heat theory of chemical reactions in Chap- 

 ter VIII. Chapter IX., the last in the book, contains a study of 

 dissociation, theoretical and practical. It will be noticed that 

 the author has confined himself strictly to his outline as planned, 

 and the work is, as the title indicates, merely an introduction to 

 the further and advanced study of explosives, but it is such an 

 introduction as comes from a master hand, and Is suggestive of 

 latent power and of the ability to pursue the demonstration to its 

 completion. C. P. 



There \vill be given at the gallery of the Boston Art Club, 

 under the auspices of the Appalachian Mountain Club, from the 

 6th to the 34th of May, a remarkable exhibition of mountain 

 photographs by Vittorio Sella of Biella, Italy. In addition to the 

 exhibit (327 subjects) to which the " diploma of honor and large 

 gold medal " has just been awarded at the competitive exhibition 

 in Turin, it is expected that nearly two hundred other subjects 

 will be represented, making it the most extensive exhibition of 

 Sella's work ever given. The collection will fully represent the 

 mountains of Dauphiny, Switzerland, the Tyrol, Sicily, and the 

 Caucasus. 



— Lieutenant Peary of the United States Navy, during his 

 coming expedition to northernmost Greenland, will record ob- 

 servations of the aurora, upon a plan that will enable compari- 

 sons to be made in detail with records from other localities. The 

 plan is already in operation, upon an international basis, and the 

 results are proving to be important. Numerous observers vridely 

 distributed are desirable, and, inasmuch as even those who have 

 no special technical knowledge may make entries that wiU be of 

 value, any who feel so disposed may cooperate. Further infor- 

 mation and supplies of blanks may be obtained from M. A. Veeder, 

 Lyons, New York, U.S.A., who will be glad to receive, also, any 

 records of observations of the aurora whatever, for purposes of 

 comparison. 



ATonic 



For Brain- Workers, the Weak and 

 Debilitated. 



Horsford's Acid Phosphate 



is without exception the Best 

 Remedy for reUeving Mental 

 and Nervous Exhaustion; and 

 where the system has become 

 debilitated by disease, it acts as 

 a general tonic and vitalizer, 

 affording sustenance to both 

 brain and body. 



Dr. J. C. Wilson, Philadelphia, Pa, 

 says: *' I have used it as a general tonic, 

 and in particular in the debility and 

 dyspepsia of overworked men, with sat- 

 isfactory results." 



Descriptive pamphlet free. 

 Rumford Chemical Works. Providence, R. I. 



Beware of Substitutes and Imitations. 



Exchanges. 



[Freeof charge to all, if ofsatisfactory character 



Address N. D. C. Hodges, 874 Broadway, New York.l 



Texas Plants. I will collect sets of plants repre- 

 sented in this region of Texas, either for sale or 

 for exchange for literature, for anyone who will 

 send me an order in time to fill it. Plants to be 

 ready complete in November. C. F. Maxwell, Box 

 174, Dublin, Texas. 



For sale or exchange— A Telescope (36 diameters, 

 copper barrel)— for $20 cash or scientific books of 

 that value. A. N. Somers, La Porte, Ind. 



For sale— A complete set of the Reports of the 

 Second Geological Survey of Pa., 1874-1893, includ- 

 incthe Grand Atlas. Publisher'spriceover$115. Will 

 sell for $50. Address F. D. Chester, Newark, Del. 



The undersigned has skins of Pennsylvania and 

 New Jersey birds, as well as other natural history 

 specimens: which he wishes to exchange for ma- 

 rine, fresh water, and earthworms of the South and 

 "West. Correspondence with collectors desired. 

 J. Percy Moore, School of Biology, University of 

 Pennsylvania, Philadelphia. 



For sale or exchange. — I have a Caligraph type- 

 writer (No. 2) in perfect order and nearly new. It 

 is in a heavy leather, plush-lined office case, the 

 whole costing me about $100. I desire to obtain for 

 it, either by sale or exchange, anew. No. 5 "Kodak" 

 camera, with six double feather-weight plate-hold- 

 ers and the latest pattern of their tripod. The lens 

 and pneumatic time-shutter must also be the same 

 as those now sold with the last No. 5 Kodftk. The 

 price of what I desire in exchange is $78. Address, 

 for particulars, P. O. Box 314, Takoma, District of 

 Columbia. 



For sale.— An Abbe binocular eye-piece for the 

 microscope. Alfred C. Stokes, 527 Monmouth St., 

 Trenton, N. J. 



For sale or exchange.- One good long range Rem- 

 ington B. L. rifle, 44 calibre, also land and fresh 

 water, and marine shells. Want shells. Safety, 

 camera or printing press. A. H. Boies, Hudson, 

 Mich. 



Fine collection of microscopic slides for sale, or 

 would exchange for first-class pneumatic bicycle. 

 J. E. Whitney, Box 549, Rochester, N. Y. 



For sale— A Zentmayer new model V. S. Army 

 Hospital monocular stand. Price SllO, will sell for 

 $75. Address H. C. Wells, No. 151 Broadway, New 

 York. 



Wants 



WANTED, as principal of a flourishing technical 

 school, a gentleman of education and experi- 

 ence who will be capable of supervising both me- 

 chanical and common school instruction. Special 

 familiarity with some technical branch desirable. 

 Address, ^ving age, qualifications, etc., J. B. Bloom- 

 ingdale, Fifty-ninth street and Third avenue, N. Y. 



WANTED. — A young man as assistant in our 

 microscopical department. Queen & Co., 

 Philadelphia. 



THE undersigned desires specimens of North 

 American Gallinae in the fiesh for the study of 

 their pterylosls. These species are especially de- 

 sired : CoUnus ridgwayi, cyrtonyx montezumae, 

 deudragapitsfranklini,lagopuswelchiytyinpa7iu€hus 

 cupido and pedioecetes phasianellus. Any persons 

 having alcoholic specimens which they are willing 

 to loan or who can obtain specimens of any of the 

 above are requested to communicate with Hubert 

 Lyman Clark, 3922 Fifth Avenue, Pittsburgh, Pa. 



A COMPETENT TEACHER of botany in coUege 

 or university is open to engagement. Address 

 L., Box 86, Rochester, Mich. 



CAN any one inform me as to the age to which 

 cats have lived? I have one twenty years old. 

 Edward D. Webb, 132 W. Eighty-first St., New York. 



WANTED — Second-hand. Foster's Physiology, 

 Balfour's Comparative Embryology, Claus & 

 Sedgwick's Zoology, Flower's Osteology of Mam- 

 malia, Vine's Physiology of Plants. Please state 

 editions and prices asked and address Richard 

 Lees Brampton, Ontario, Canada 



A GRADUATE ENGINEER will give instruction 

 evenings in geometry, trigonometry and sur- 

 veying, mechanics, physics, mechanical drawing 

 and general engineering construction. Five years' 

 experience in field and editorial work on engineer- 

 ing journal. References furnished. C. S. H., 102 

 Tribune Building, New York. 



WANTED. — &y well - qualified and experienced 

 science master and assooiate of the Royal 

 School of Mines, London, aged 26 (at present in 

 England), a mastership »n technical coUege or uni- 

 versity for any of the following subjects: Engineer- 

 ing sciences, geology and mineralogy, physics, chem- 

 istry and metallurgy, etc.. etc. Can provide excel- 

 lent references and credentials. Apply, J. G., 17 

 Sussex St., Rochdale, England. 



