899 
lead the temperature of the core appears to have risen about '/, degree 
above the mean temperature of the lead block during the heating, 
in the measurement with copper, for which the heat supply per 
second was chosen smaller in accordance with the smaller specific 
heat, the corresponding temperature difference is not appreciable. 
Where necessary, corrections for the heat exchange with the bath 
were applied. 
The heat supply. The arrangement for sending a current of mea- 
sured intensity and potential difference during a definite time through 
the constantin heating wire is represented in Fig. 5 together with 
the arrangement ') for measuring the resistance of the gold thermo- 
ä 
FE S 
oes. 
= fel 
ee, 
Fig. -b. 
meter wire. Intensity and potential difference were read on accurate 
Weston millivolt- and voltmeters. These were calibrated repeatedly 
for the measuring ranges used with the aid of a standard element 
of the Weston Cy., standard resistances and a compensation apparatus 
free from thermoelectric forces with an auxiliary apparatus according 
to DiessenHorst, all calibrated at the Physikalisch Technische Reichs- 
Fig, 6. 
1) In the figure the regulating. resistance and the milli-ampèremeter between 
accumulator and commutator have been omitted. 
