14 
AN APPARATUS FOR OBSERVING SPLASHES. 
the release of the lever, R is lowered and makes contact, so 
that the current passes, but is immediately after broken by the 
wire M leaving the mercury N and producing the flash. In this 
way the battery is kept from w'aste, and bichromate cells can be 
used without renewal for many weeks, which, but for this pre- 
caution, would run down in as many minutes. 
For an account and explanation of the phenomena observed 
with this apparatus, the reader is referred to the Proceedings of 
the Royal Society, vol. '25, pp. 261 and 498 (1877), and vol. 3i, 
p. 217 (1882). 
