( 193 ) 



The mean deviation of Ec for the ditferent days from the mean 

 vahie, and also the mean largest deviation of the vahies o[ Ec found 

 on one day amounts to 3 microvolts, which amount shows that in 

 the observation of the comparison-element the necessary care has 

 not been bestowed on one or other detail, which has not been 

 explained as yet. We must come to this conclusion because the 

 observation-element yields for this mean only 1,8 microvolt. 



§ 10. Indirect determinations. 



In order to arrive at the most suitable representation of Ei^ as a 

 function of t, it was desirable not only to make use of the obser- 

 vations communicated in § 9 but also to avail ourselves of a large 

 number of indirect measurements, obtained through simultaneous 

 observations of the thermo-element and a platinum-resistance thermo- 

 meter, the latter having been directly compared with the hydrogen 

 thermometer (comp. Comm. N". 95^, this meeting). 



These numbers have been combined in table VII where the columns 

 contain the same items as in the preceding table, except that here 

 the temperatures are derived from resistance measurements. 



TABLE VII. 

 INDIRECT CALIBRATION OF THE THERMO-ELEMENT 

 CONSTANTIN-STEEL. 



