In connection with the calorimeter and the accessories, mercurial and
electric-resistance thermometers are employed. For measuring the
temperature of the water as it enters and leaves the chamber through
horizontal tubes, mercurial thermometers are used, and these are
supplemented by electric-resistance thermometers which are connected
with a special form of recording instrument for permanently recording
the temperature differences. For the measurement of the temperatures
inside of the calorimeter, two sets of electric-resistance thermometers
are used, one of which is a series of open coils of wire suspended in
the air of the chamber so as to take up quickly the temperature of the
air. The other set consists of resistance coils encased in copper boxes
soldered to the copper wall and are designed to indicate the temperature
of the copper wall rather than that of the air.