-irr-r 

 1894.] -•- • • [Prime. 



I must confess that, although every conckision reached through 

 labor bestowed gives a certain pleasure in legitimate appetite for 

 knowledge gratified, yet this is so far beneath what I had thought 

 might lie hidden under the mystery of the brownian movements, 

 I experience a sense of disappointment. I had thought that this 

 investigation might be one of the paths that lead to the solution of 

 the question whether or not energy is immanent in matter or a thing 

 apart from it. For many years after the beginning of this century 

 nothing fundamental in physics was known beyond the fact that 

 matter is indestructible. It has been learned since, but no longer 

 ago than about fifty years, that energy also is indestructible. It 

 still remains perhaps to be shown that energy is but an emanation 

 and manifestation of matter, reacting on it. Advanced as our 

 knowledge is within a few years as to molecular movement, I had 

 hoped that the investigation of the brownian movements might 

 yield some contribution to molecular theory, and thence lead to a 

 profounder knowledge than we now possess of molecular behavior 

 in the abstract. I am able, however, to claim for the demonstra- 

 tion here no more than that the brownian movements are not the 

 self-movements of finely divided particles in suspension in aqueous 

 solutions, which Herr Wiener had also ascertained, but simply that 

 which he did not ascertain, movements generated by the molecular 

 action of aqueous fluids, instead of being, as he and Herr Exner 

 also thought, in differing form, phenomena due to light and heat. 

 Perhaps even this moderate conclusion may be disputed, but it 

 remains to be disproved. 



Obituary Notice of Thomas Mutter Cleeman. 



By Frederick Prime, 



{Read before the American Philosophical Society, April 6, 1S94 ) 



In the year just past, this Society has been called on to mourn the loss 

 of more than the usual number of its resident members. Of these many 

 were taken in the ripeness of their years with their life's work accom- 

 plished ; some, however, were still in the full vigor of manhood, with 

 apparently a long career still before them. To the latter chiss belonged 

 the subject of this sketch. 



Thomas Mutter Cleeman was born in Philadelphia, July ?A, 1843. In 



