May 5, 1905.] 



SCIENCE. 



697 



oins, is to the west of Manzanilla Bay ; a 

 third, to the southeast of Acapulco, has 

 about the same depth, and a fourth, with 

 2,500 fathoms, is off San Jose, Guatemala. 

 Our last sounding off Acapulco about 29 

 miles south of the lighthouse, in 2,49-4 fath- 

 oms, showed the western extension of one 

 of these deep holes to the east of Acapulco. 

 These basins off the west coast, close to the 

 shore at the foot of a steep continental 

 slope, are in great contrast to the wide con- 

 tinental shelves which characterize the east 

 coast of Central America and the east coast 

 of the United States. 



The collections made during the present 

 expedition will give ample material for ex- 

 tensive monographs on the holothurians, 

 the siliceous sponges, the cephalopods, the 

 jelly-fishes, the pelagic crustaceans, worms 

 and fishes of the eastern Pacific, as well as 

 on the bottom deposits and on the radio- 

 larians and dinoflagellates, diatoms, and 

 other protozoans collected by the tow nets. 

 Small collections of plants were made at 

 Easter Island and Manga Reva which may 

 throw some light on the origin and dis- 

 tribution of the flora of the eastern Pacific. 



SCIENTIFIC BOOKS. 

 Radioactivity. By E. Rutherford, D.Sc, 

 E.RS., E.E.S.C., MacDonald Professor of 

 Physics, McGill University, Montreal ; Cam- 

 bridge Physical Series. Cambridge, Uni- 

 versity Press, 1904. 



Within recent years books dealing speci- 

 fically with radioajctivity or the cathode rays 

 have naturally not been infrequent. Begin- 

 ning with the pioneering treatise of Stark 

 (' Elektricitiit in Gasen,' 1902), Madam Curie's 

 account of radioactive substances, Villard's 

 ' rayons cathodiques,' G. C. Schmidt's ' Kath- 

 odenstrablen ' (1904), Besson and D'Arsonval's 

 ■'Le radium' (1904), Blondlot's 'rayons N ' 

 (1904) and others, have followed in quick suc- 

 cession. But Mr. Rutherford's book is on 

 quite a different scale from most of these, and 

 written in a way that betrays consummate 



mastery of the subject. One would have been 

 grateful if he had given us merely a sys- 

 tematic accouiat of his own researches. The 

 book before us does much more than this, 

 presenting a readable and most painstaking 

 digest of the subject as a whole, or at least of 

 that splendid part of it which owes its develop- 

 ment chiefly to English genius. 



In the introductory part separate chapters 

 are devoted to radioactive substances, to the 

 theory of ionization, and to methods of meas- 

 urement. Then comes a long account of the 

 nature of the radiations. The sharply artic- 

 ulated descriptions which follow, and the sug- 

 gestions lavishly offered for the completion 

 of most of them, are a feature of the book here 

 and in succeeding chapters. The short ac- 

 count of the rate of emission of energy is 

 absorbingly interesting, and would be startling 

 if our expectation were not blunted by the ex- 

 pressions of astonishment so much in vogue 

 in connection with this subject. In the chap- 

 ter on radioactive matter, Mr. Rutherford de- 

 velops the important principle that the activ- 

 ity of a product at any time is proportional 

 to the number of atoms which remain un- 

 changed at that time, a subject to which he 

 has himself so prolifically contributed. This 

 is supplemented by a long chapter on radio- 

 active emanations, giving a succinct account 

 of the work for which the Rumford medal of 

 the Royal Society was recently awarded. 



The interesting phenomenon of excited 

 radioactivity, of which Rutherford shares the 

 honor of discovery with the Curies, is next 

 discussed in detail and leads naturally to the 

 final resume on radioactive processes, in which 

 the full theory of atomic disintegration is de- 

 veloped. The consequences of this theory 

 have been brilliantly substantiated, even in 

 the more recent papers which Rutherford con- 

 tributed to the congress at St. Louis and else- 

 where. At the end of the chapter is a sum- 

 mary of the present state of our knowledge 

 of the age of the sun and of the earth. The 

 book closes with an account of the radioactiv- 

 ity of ordinary materials. 



We have noticed but few misprints : p. 55, 

 m for w ; p. 265, t for n ; p. 336, omission of dt. 

 We should have been grateful, however, for a 



