1 66 POPULAR LECTURES AND ADDRESSES. 



" the form and motion of the parts of each atom 

 " and the distances by which they are separated 

 " may be calculated ; that the motions by which 

 " they produce heat, electricity, and light may be 

 " illustrated by exact geometrical diagrams ; and 

 " that the fundamental properties of the intermc- 

 " cliatc and possibly constituent medium may be 

 " arrived at. Then the motion of planets and 

 " music of the spheres will be neglected for a 

 " while in admiration of the maze in which the 

 " tiny atoms run." 



Even before this was written some of the 

 anticipated results had been partially attained. 

 Loschmidt in Vienna had shown, and not 

 much later Stoney independently in England 

 showed, how to deduce from Clausius and Max- 

 well's kinetic theory of gases a superior limit 

 to the number of atoms in a given measurable 

 space. I was quite unaware of what Loschmidt 

 and Stoney had clone when I made a similar 

 estimate on the same foundation, and communi- 

 cated it to Nature in an article on " The Size 

 of Atoms." But questions of personal priority, 

 however interesting they may be to the persons 



