494 Mr. A. Mullock and Lieut-Col. A. M. Uavies. [Nov. oO, 



by levers with the rod at (H), marking on uniformly moving paper, 

 indicated the position of the pointer at each instant. Time was also 

 recorded on the paper by means of another pen (L) worked from an 

 electric clock beating seconds. 



During an experiment the pointer was kept carefully on the end of 

 the mercury column in the thermometer, so that the diagram on the 

 paper gave the temperature of the tubes in terms of time. 



FIG. 1. 



The tube in which the thermometer bulb dipped had the same amount 

 of water in it, to start with, as was contained in the culture tubes, but 

 as the thermometer tube was open to the steam in the chamber, and 

 the culture tubes were scaled, the water in the former would acquire 

 the temperature of the steam more rapidly than the liquid in the 

 culture tubes. Thus the temperature to which the cultures were 

 exposed must have been a little less than that recorded, but only 

 when the times of heating were very short would the difference be 

 appreciable. 



