64 



SCIENCE. 



[N. S. Vol. XVI. No. 393. 



tington ; ' Determination of All tlie Groups of 

 Order p '", p being any Prime, which Contains 

 the Abelian Group of Order p'"-^ and of Type 

 (1, 1, 1, . . . ),' by G. A. Miller; 'A Class of 

 Simply Transitive Linear Groups/ by L. E. 

 Dickson ; ' Errors in Legendre's Tables of 

 Linear Divisors,' by D. N. Lehmer; reviev? of 

 ' Recent Books on Mechanics,' by E. B. Wilson ; 

 review of Kiepert's ' Calculus,' by E. W. Davis ; 

 ' Correction ' ; ' Notes ' ; ' New Publications.' 



DISCUSSION AND GORBESPONDENGE. 



FORCE AND ENERGY. 



To THE Editor of Science : In my address, 

 published in your number for July 4, I have 

 used the word 'force' without saying as clear- 

 ly as I should have done that it is used in the 

 sense of energy, as that term is now applied 

 in physics. It seemed to me that to a general 

 audience force would be more significant. As 

 Helmholz wrote of the Erhaltung der Kraft, 

 perhaps an outsider may be pardoned for us- 

 ing 'force' with the above defined meaning. 

 Charles S. Minot. 



Boston, July 5, 1902. 



ETHER WAVES FROM EXPLOSIONS. 



About a year ago the writer began a system- 

 atic attempt to examine into the effect of ex- 

 plosions upon the ether. A few prior experi- 

 ments had yielded results explainable on the 

 assumption that such action existed. The in- 

 vestigation was suggested by Young's observa- 

 tion upon a solar outburst as given in his work 

 on the sun.* The Greenwich magnetic curves 

 which Young gives for the dates August 3 and 

 5, 1872, are so persuasive in their character 

 that an attempt was made to reproduce these 

 results by a terrestrial explosion. It was also 

 thought that the motion of rifle bullets might 

 yield some recognizable result. 



It seems probable that, in order to produce 

 a magnetic disturbance, recognizable by a 

 needle, the explosion should be as large and 

 violent as possible. With the coherer as a 

 receiver, it would seem that sharpness of the 

 explosion and atomic periodicity might be 

 more directly involved. 



*'The Sim,' 1881, pp. 156-159. 



The work has been attended with great diffi- 

 culty. The buildings and grounds of Wash- 

 ington University, where the work has been at- 

 tempted, are in the heart of the city of St. 

 Louis, and street cars are almost continually 

 passing. Only between two and three o'clock 

 in the morning was it found possible to obtain 

 brief intervals fairly free from great disturb- 

 ance. Even then the needle was continually 

 in motion. The explosions at such an hour 

 were necessarily limited in violence by the 

 possibilities of damage to property, and have 

 been doubtless an outrage upon people who 

 wished to sleep. 



So far the results have been inconclusive. 

 Deflections have been obtained, but they have 

 not been reducible to any system which could 

 be rationally explained. It was apparent that 

 the sound wave and the shock have been in- 

 volved. This work will be carried on in the 

 open country, where larger explosions can be 

 made at a distance from the receiving appa- 

 ratus. In the meantime it is most interesting 

 to know that the volcanic explosion on the 

 island of Martinique has apparently produced 

 the results which we had been seeking. 



Francis E. Nipher. 



ECOLOGY. 



To THE Editor of Science : Doubtless your 

 readers are heartily tired of the discussion 

 upon the word ecology, and I shall not attempt 

 to reply to Mr. Bather's letter in your issue of 

 June 20, farther than to state that his ex- 

 planation does not appear to me to improve 

 his case materially beyond providing an ample 

 cloud to cover a graceful retreat. 



But aside from the main points at issue, I 

 agree with Mr. Bather that the use of the word 

 ecology in such an expression as ' the ecology 

 of a glacial lake' is somewhat unfortunate. 

 Every botanist interested in such studies 

 knows that this phrase is simply a convenient 

 abbreviaton for ' the ecological relations [or 

 features, etc.] of the vegetation of a glacial 

 lake,' and, when used in a botanical publication, 

 it produces no misunderstanding. Neverthe- 

 less, as the present discussion has shown, it may 

 mislead others, and therefore botanists could 

 better use the word in such a way as to make 



