154 



SCIENCE. 



[N. S. Vol. IX. No. 213 



Pacific side and their ejecta built a dam across 

 the outlet of the gulf, thereby forming the lake 

 basin. As this dam increased in height the 

 waters behind it were raised until they over- 

 topped the continental divide and escaped to 

 the Atlantic, forming the present San Juan. 

 The region has suffered a recent depression by 

 which thQ rivers were drowned, and their estu- 

 aries thus formed have since been silted up. 

 Wm. F. Morsell. 



DISCUSSION AND COBBESPONDENCE. 

 MATTEE, ENERGY, FORCE AND WORK. 



To THE Editor of Science : In the generous 

 and appreciative review by Professor Menden- 

 hall (in Science, p. 24, January 6) of my book 

 on ' Matter, Energy, Force and Work ' there 

 occurs a line to which I would like to advert 

 briefly. "'The something' which distin- 

 guishes substance from matter is energy. ' A 

 designated quantity of substance consists of a 

 definite quantity of matter in permanent as- 

 sociation with a definite quantity of energy or 

 motion.' The two words 'or motion' render 

 this statement somewhat obscure. What is 

 meant by a ' definite quantity of motion? ' Pro- 

 fessor Holman's definition of motion is that of 

 nearly all writers, namely, ' change of relative 

 position.' It is a curious but common practice 

 to define it in this way and then to define its 

 ' quantity ' by associating with it something 

 (matter, mass) absolutely unlike it in every re- 

 spect. It is certainly not in this sense that he 

 means to use it in the phrase above quoted." 



I desire to express my assent to this comment 

 and to reply to the query therein contained, or 

 rather to remove, if I may, the obscurity. 

 This result will, I think, be effected if for the 

 words ' of motion ' in the description of sub- 

 stance be substituted the phrase : or permanently 

 endued with some definite mode of motion. 



May I also add, to preclude possible misap- 

 prehension, that the proposition ' Continuous, 

 uniform, and permanent occupancy of space,' 

 quoted at page 25, is one which I do not ad- 

 vance as a definition of matter, or as a logical 

 deduction from known premises, but only as a 

 possible view of matter if the improved hy- 

 pothesis of the kinetic nature of all energy be 

 adopted as a step in the inference. 



With sincere thanks for your courtesy in pre- 

 senting this review, I am 



Yours truly, 

 Silas W. Holman. 

 Brookline, Mass., January 17, 1899. 



zoological bibliography. 



To THE Editor of Science : Dr. Ball's ' tol- 

 erably active and rather long experience' has 

 been singularly blessed if he has never met with 

 an advance copy of a paper issued at an uncer- 

 tain date, not offered for sale, and conflicting 

 in its contents with some other paper offered 

 for sale at a known date about the same period; 

 if he or the libraries he frequents have always 

 been able to purchase without a delay of more 

 than one year the new books or pamphlets that 

 he wanted to see ; if he has always had so much 

 as a printed postcard in reply from authors 

 whose works he has sought in exchange for his 

 own ; and if he has always been able to find 

 the address of every writer with whom he 

 wished to communicate. A restricted and short 

 experience has acquainted me ftir too thoroughly 

 with all these difliculties, but, as this is not an 

 autobiography, the details need not be inflicted 

 on your readers. Dr. Dall shall have them if 

 he wishes. 



Apart from his scepticism. Dr. Dall appears to 

 agree, at least in spirit, with the proposal that 

 he has now twice criticised. But two remarks 

 of his seem to call for reply. 



My committee has not yet definitely pro- 

 nounced on the question : What constitutes 

 publication ? But it is safe to say that it does 

 not regard printing as publication, and therefore 

 sees no great value in placing ' the actual date 

 of printing' on every signature. This, too, may 

 be said : That a British Association Committtee 

 would never recommend an author to sell his 

 papers without an express agreement with the 

 society that has been at the expense of setting 

 up the type, and perhaps of drawing the plates. 

 In our country this may be done, but it is not 

 regarded as particularly creditable to the au- 

 thor that does it. Customs are, no doubt, dif- 

 ferent elsewhere ; but our proposal was an 

 attempt to render the speediest possible 

 publication compatible with commercial mo- 

 rality as recognized here. Perhaps it is this 



