was formerly used in
weighing the man inside the chamber.[7]

THERMOMETERS.

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.

MERCURIAL THERMOMETERS.

The mercurial thermometers used for measuring the temperature
differences of the water-current are of special construction and have
been calibrated with the greatest accuracy. As the water enters the
respiration chamber through a horizontal tube, the thermometers are so
constructed and so placed in the horizontal tubes through which the
water passes that the bulbs of the thermometers lie about in a plane
with the copper wall, thus taking the temperature of the water
immediately as it enters and as it leaves the chamber. For convenience
in reading, the stem of the thermometer is bent at right angles and the
graduations are placed on the upright part.

The thermometers are graduated from 0 deg. to 12 deg. C. or from 8 deg. to
20 deg. C. and each degree is divided into fiftieths. Without the use of a
lens it is possible to read accurately to the hundredth of a degree. For
calibrating these thermometers a special arrangement is necessary. The
standards used consist of well-constructed metastatic thermometers of
the Beckmann type, made by C. Richter, of Berlin, and calibrated by the
Physikalische Technische Reichsanstalt. Furthermore, a standard
thermometer, graduated from 14 deg. to 24 deg. C., also made by Richter
and standardized by the Physikalische Technische Reichsanstalt, serves
as a basis for securing the absolute temperature. Since, however, on the
mercurial thermometers used in the water-current, differences in
temperature are required r