212 



Sir William Thomson 



[Feb. 2, 



through a space equal to 1000 times the sum of their volumes. Such 

 a crowd may be condensed (just as air may be condensed) to 1-lOOOth 

 of its volume, but this condensation brings the molecules into contact. 

 Something comparable with this may be imagined to be the condition 

 of common air of ordinary density, as in our atmosphere. The 

 diagram with size of each molecule, which, if shown in it to scale, 

 would be 1 millimetre (or too small to be seen by you), to represent 



Fig. 11. 



Diagram illustrating the number of molecules in a space of 1-1 0,000th of a 

 centimetre square and l-100,000,000th of a centimetre thick. 



100 holes in ten rows of ten holes each. From each hole was suspended a cord 

 five metres long. To the lower end of each cord, in five contiguous rows, there 

 was secured a blue coloured glass ball of four centimetres diameter ; and similarly 

 to each cord of the other five rows, a red coloured ball of the same size. A ball 

 from one of the outer rows was pulled aside, and, being set free, it plunged in 

 amongst the others, causing collibions throughout the whole plane in which the 

 Buspended balls were situated. 



