Apkil 2, 1915] 



SCIENCE 



507 



r(m + l) =mr(n) = w,(?i — 1) (w — 2) 



. . . (n — r) r (n — r). (ii) 



It becomes an exceedingly tedious operation 

 when n has a value of over, say, 20. In calling 

 this the " exact " value in the table the inten- 

 tion is merely to convey the idea that the only 

 approximation involved is that incident upon 

 the use of V-place logarithms, the process 

 per se being an exact one. The fourth and 

 fifth columns of the table give the results ob- 

 tained by using the values of log \n, their first 

 second and third differences, in the usual ad- 

 vancing difference interpolation formula 



«a;+« = w^ + « A M^ 



-Jr^C^A^u^+nO.A^u^---. (iii) 



TABLE I 



Values of log T (re) hy Different Methods 



Trom this table it is evident that the inter- 

 polation method, when third differences are 

 used, gives values slightly better than those by 

 Forsyth's method when n g 25. For n = 75 or 

 more the interpolation method using only 

 second differences gives an approximation 

 sufficiently close for all practical statistical 

 purposes. As to the labor involved, there is no 

 great amount of choice between Forsyth's and 

 the interpolation method, but on the whole 

 there appears to be a distinct, if small, advan- 

 tage in favor of the interpolation. 



Eaymond Pearl 



TBE GEOLOGICAL SOCIETY OF AMERICA 

 The twenty-seventh annual meeting of tlie Geo- 

 logical Society of America was held at the Acad- 

 emy of Natural Sciences, Philadelphia, December 

 29-31, 1914, under the presidency of Dr. George 

 P. Becker, of the "United States Geological Survey, 

 ton, D. C. On, account of Dr. Becker's 



enforced absence through illness, the sessions were 

 presided over by Vice-presidents Waldemar Lind- 

 gren and Horace B. Patton. In attendance there 

 were registered 117 Fellows of the Society and the 

 number of students and others, including members 

 of the American Association for the Advancement 

 of Science who were present at the sessions, 

 swelled the attendance to more than 200, making 

 this one of the most largely attended meetings in 

 the history of the society. 



At the first general session of the society Dr. 

 Samuel G. Dixon, president of the Academy of 

 Natural Sciences, welcomed the visiting geologists 

 and paleontologists, making them feel very much 

 at home as the guests of the historic academy. 



The report of the council, as submitted in print, 

 showed that the present enrollment of the society 

 is 363, aside from the 19 new fellows elected at 

 the meeting but who had not yet qualified. Dur- 

 ing the year 1914 the society lost five fellows by 

 death : Alfred E. Barlow, Albert S. Bickmore, Hor- 

 ace C. Hovey, A. B. Wilmott and Newton H. 

 Winohell; and three correspondents: H. Rosen- 

 busch, Eduard Suess and Th. Tschemyschew. The 

 treasurer's report showed that the society was in a 

 flourishing condition financially and the editor's 

 report indicated an unusual activity in publication 

 during the past year. 



The papers presented in the three general ses- 

 sions of the society were as follows: 

 delation of Bacteria to Deposition of Calcium Car- 

 bonate: Karl F. Kellerman. 

 At the suggestion of Dr. T. Wayland Vaughan, 

 bacterial studies of water and bottom mud from 

 the Great Salt Lake, and sea water and bottom de- 

 posits from the vicinity of Florida and the Ba- 

 hamas were undertaken in the hope of supplement- 

 ing the work of Vaughan,i of Drews and of Doles 

 in regard to the probable agencies concerned in 

 the precipitation of calcium carbonate and the 

 formation of oolites. 



It has been possible to form calcium carbonate 

 by the action of bacteria on various soluble salts of 

 calcium both in natural waters and in synthetic 

 mixtures. The most important natural precipita- 



1 T. Wayland Vaughan, Bull. Geol. Soo. Am., 

 Vol. 25, No. 1, p. 59, March, 1914. Also Publica- 

 tion No. 182, Carnegie Inst, of Washington, pp. 

 49-67. 



2 G. H. Drew, Publication No. 182, Carnegie Inst, 

 of Washington, pp. 49-67. 



3 E. B. Dole, Publication No. 182, Carnegie Inst, 

 of Washington, pp. 69-78. 



