500 



Sir William Thomson 



[Jan. 29, 



Fig. 15. 



Fig. 16. 



Fig. 17. 



Fig. 18. 



^Bfrl- m Fig. 19. 



m Fig. 20. 



Fig. 21. 



Fig. 22. 



Water in glass tubes, the internal diameter of which may be found from Fig. 22, 

 which represents a length of one centimetre. 



Fig. 23. 



Water resting in the space between a solid cylinder and a concentric hollow cylinder. 



