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Mr. Dugald Clerk 



[Jan. 29, 



in the exhaust pipe was 150° C. Professors Callendar and Dalby also 

 determined the temperature of explosion in a gas engine cylinder, but 

 they did not attempt to measure the maximum temperature by any 

 thermo-metric arrangement. In closed vessel experiments, as has 

 been pointed out, it is easy to determine accurately the initial 

 temperature before explosion, but in actual gas engine experiments, 

 what is called the suction temperature presents serious difficulties 

 of measurement. If the suction temperature — that is, the temperature 



Fig. 22. — Thermo-Electric Bridge. 



of the charge just after it has filled the cylinder— be known, and also 

 the pressure of the charge, then, consfdering the gas as its own 

 thermometer, all the other temperature points can be calculated. 

 Professors Callendar and Dalby proceeded by determining the tem- 

 perature of the charge in the inlet port of the engine cylinder. 

 To do this they applied the platinum resistance thermometer to the 

 determination of both suction and compression temperatures by the 

 use of an ingenious attachment to the charge inlet valve of a four- 

 cycle engine. 



