CONTROL OF INCUBATING TEiMPERATURES IN LABORATORIES. 15 



these temperature variations may be materially lessened if the door 

 is quickly opened and closed and kept closed while storinj^ or remov- 

 ing specimens. A similar chart, figure 12, covering the week August 

 6 to 13, 1918, shows the results obtained during a typical summer 

 period. The incubator room was entered only about twice during 

 this week; consequently the temperature was maintained practically 

 constant throughout the period. 



Fig. 12. — ('hart showing teminTatures niaiiitainod in incubating room of rathological 

 Division, August 6 to 13, 1018. Note that variations are exceedingly small. 



The chart in figure 13 was taken in one of the incubator rooms 

 equipped with a control system made up largely of asseml)led com- 

 mercial apparatus. The curve shows that while the average tem- 

 perature was about that for whicli the control was adjusted it was 

 not so uniform as the tenii)eratures shown in the previous charts. 

 While this latter temperature-control system is not so sensitive or 

 reliable as the former, and hence recpiires closer attention and more 

 frequent adjustments, it has the advantage of being assembled from 

 commercial apparatus. 



