74 Chemical and Physical Notes 



cooling the excess is 6'8, and log 6*8 is 0-8325. Taking the 

 initial excess as unity, the fractional excess, or the heat 



/T.Q 



remaining after the first interval of ten seconds, is , and 



its logarithm is 0-8325 0-9031 =1*9294 = log y. After the 

 second interval of ten seconds the excess is 5'8, and 

 log 5-8 = 07634. The fractional excess after the second 



interval is | , and its logarithm is 07634 - 0-903 1 



o'O 



TABLE IX. 



1-8603. 



According to the theory which has been explained above, 

 if the thermometer in cooling loses in each equal interval of 

 time exactly the same fraction of the excess heat which it 

 held at the beginning of the interval, and if the observations 

 are without error, then the logarithms of the fractional excess 

 after the second interval ought to be 2x1-9294 = 1-8588 in 

 place of 1-8603, as above. The difference is obviously not 

 great. In order to know what it amounts to in the observation 

 of the temperature we have 1-8588 -f 0*9031 =07619 = 578, 

 which ought to be the excess of the temperature of the 



