168 Prof. Potter on the Relations of tlie Elastic Force, 



The jet caused the thermometer in the chamber to rise with cer- 

 tainty when the differences were also o, 6, 0°*45, 0°*3 ; but it 

 fell when they were only o, l and o, 15. 



The results in the table below were obtained under the best 

 conditions, and it will be seen that I was fortunate enough at 

 length to get the differences of temperature when no effect was 

 produced by the jet for rarefactions two and one nearly, and so 

 to determine the relation required ; but we must expect some 

 correction of the constant when greater rarefactions have been 

 employed with certainty. I think it quite probable some methods 

 can be found for using higher rarefactions or condensations, 

 and have in view such further experiments myself. 



