Remarks on a neiv Theory of Dew. 483 



Therefore the chance that the angle COp shall lie between <f> 

 and <f} + d(j) is proportional to sin <£ d<p. And therefore, as 

 stated in (1), for any given direction of pOq all directions of 

 00 are in Maxwell's distribution equally probable. 



If Maxwell's distribution does not exist, then for any direc- 

 tion of pQq some directions of 00 are more probable than 

 others before collision. After collision all are equally pro- 

 bable ; I think it follows that collisions tend to bring about 

 Maxwell's distribution. 



LXVII. Remarks on a new Theory of Dew. 

 By Chakles Tomlinson, F.R.S.* 



ME. AITKEN read before the Eoyal Society of Edin- 

 burgh, on the 21st of December last, a paper in which 

 a new theory of Dew is promulgated in opposition to that of 

 Dr. Wells, " who," he says, "has justly been considered the 

 great master of this subject." An abstract of the paper, 

 presumably by the author himself, was given in the number 

 of ( Nature ' for the 14th of January last, preparatory to the 

 publication of the memoir in the ' Edinburgh Transactions.' 



Many years ago I showed that the chief points which Dr. 

 Wells is said to have established had already been demon- 

 strated by his predecessors ; and in noticing his essay in the 

 i Quarterly Review ' for 1814, Dr. Thomas Young enters a 

 protest against " the total novelty of the opinions which Dr. 

 Wells's laborious series of experiments had so amply illus- 

 trated and confirmed ; for while the author affords us complete 

 information respecting the sentiments of Aristotle and Theo- 

 phrastus as to the nature and causes of dew, some of the works 

 of the most distinguished philosophers of modern times have 

 most unaccountably escaped his attention." 



The fact is there is a considerable difference between a 

 scientific worker and a scientific writer. The worker is gene- 

 rally too intent on his own share in discovery to do more 

 than accept the conditions of the question in hand from some 

 writer who may have compiled from earlier books and not 

 taken the trouble to consult original memoirs. There are 

 not many writers who work at scientific literature with the 

 same zeal with which literary men pursue their labours ; 

 and the reason is to be found in the marked difference be- 

 tween literature and science. A literary work bears the 

 impress of mind, scientific work bears the stamp of nature. 



* Communicated by the Author. 



