632 



THE POPULAR SCIENCE MONTHLY. 



four sections, whereof the first treats of 

 heat, the second of steam - engines and 

 boilers, the third of locomotives, and the 

 fourth of marine-enghies. 



Bulletin of the Minnesota Academy of 

 Natural Sciences for 1874. Pp. 108. 

 Price, 50 cents. 



It is gratifying to receive so substantial 

 an evidence as this of the progress of sci- 

 ence in the more recently-settled portions 

 of our country. The titles of the papers in 

 the present number are : " Birds of Minne- 

 sota," by Dr. P. L. Hatch ; " Mammalia of 

 Minnesota," by Dr. A. E. Ames ; " Report of 

 the Curator of the Museum ; " " Prerequisites 

 to a Proper Study of Science," by Dr. Charles 

 Simpson; " Minnesota Geological Notes," by 

 N. H. Winchell ; " Antiquity of Man," by Dr. 

 A. E. Johnson ; " Astronomy Scientific and 

 Unscientific," by G. W. Tinsley. 



Archives of Dermatology : a Quarterly 

 Journal of Skin and Venereal Diseases. 

 Edited by L. Dunean Bulkley, M. D. 

 New York : Putnanis. $3.00 a year. 



This is anew periodical, and as a "first 

 number" the specimen before us is excel- 

 lent. The Archives has no rival on this 

 side of the Atlantic, and this circumstance, 

 taken in connection with its intrinsic worth, 

 ought to insure its success. Besides origi- 

 nal communications, of which the present 

 number contains cix, the Archives will con- 

 tain the Transactions of the New York 

 Dermatological Society, clinical records, a 

 digest of the current literature of derma- 

 tology, reviews and bibliography, and edi- 

 torials. - 



The Protoplasm Theory. By Edward Cur- 

 tis, A. M., M. D. Pp. 23. 



Dr. Curtis is Professor of Materia Med- 

 ica and Therapeutics in the New York Col- 

 lege of Physicians and Surgeons, and this 

 is his introductory lecture for the winter 

 course of 18*73. It is an able argument for 

 the oneness of the physical basis of life 

 throughout the organic world. Though the 

 lecture was originally addressed to medical 

 students, it nevertheless may be read un- 

 derstandingly and with profit by the lay 

 public. 



Organic Chemistry. By W. Marshall 

 Watts, D. Sc, F. C. S. New York : Put- 

 mms. Pp. 130. Price, 75 cents. 



The primary aim of this little manual 

 appears to be, to fit students for passing 

 the examinations of the English '' Science 

 and Art Department." In so far as the 

 book discusses its subject-matter proper, 

 viz., the chemistry of the carbon compounds, 

 it is as full and explicit as could be ex- 

 pected, considering its size. 



Report upon Ornithological Specimens 

 collected in the Years 1871, 1872, 

 and 1873. Pp. 148. 



Catalogue of Plants collected in the 

 Years 1871, 1872, and 1873. Wash- 

 ington : Government Printing - Office. 

 Pp. 62. 



These valuable Reports form a part of 

 the published work of the geographical and 

 geological explorations under the charge of 

 Lieutenant Wheeler. The Ornithological 

 Report is by Dr. H. C. Yarrow, and has 

 been revised and corrected by Robert Ridg- 

 way, of the Smithsonian Institution. The 

 Catalogue of Plants is by Mr. Sereno Wat- 

 son and Dr. J. T. Rothrock. 



MISCELLANY. 



The Cause of " Cold Snaps." In a paper 

 read before the American Academy of Sci- 

 ence, Prof. Loomis offered a new theory to 

 account for sudden falls of temperature, or 

 " cold snaps," as they are called. The usual 

 mode of accounting for these is by suppos- 

 ing that a current of cold air sets in from 

 the north. A laborious investigation of the 

 subject has led Prof. Loomis to the conclu- 

 sion that these low temperatures, which 

 occur at irregular intervals in every month, 

 and particularly during the winter, are due 

 mainly to the descent of cold air in the 

 neighborhood, and that this descent of air 

 results from the outward movement, which 

 generally takes place from the centre of an 

 area of high barometer. The theory is fully 

 sustained by observations. As for the op- 

 posite theory, if the cold comes to us from 

 the north, "whence does it come," asks 

 Prof. Loomis, " to these colder known points 

 on the earth's surface ? " In summer, dur- 

 ing a thunder-storm, the temperature often 



