eve that with a slight improvement in
the technique a man can be weighed to within 0.3 gram by means of this
balance. A series of check-experiments to test the indirect with the
direct determination of oxygen are in progress at the moment of writing,
and it is hoped that this problem can be satisfactorily solved ere long.

During the process of weighing, the ventilating air-current is stopped
so as to prevent any slight tension on the rubber diaphragm and furnish
the best conditions for sensitive equilibrium. After the weighing has
been made and the time exactly recorded, the load is thrown off the
knife-edges of the balance, and then provision has been made to raise
the rod supporting the chair and simultaneously force a rubber stopper
tightly into the hard rubber tube at the top of the calorimeter, thus
making the closure absolutely tight. It is somewhat hazardous to rely
during the entire period of an experiment upon the thin rubber membrane
for the closure when the blower is moving the air-current.

To raise the chair and the man suspended on it in such a way as to draw
the cork into the hard-rubber tube, we formerly used a large hand-lever,
which was not particularly satisfactory. Thanks to the suggestion of Mr.
E. H. Metcalf, we have been able to attach a pneumatic lift (fig. 9) in
that the cross-bar above the calorimeter chamber, to which the
suspension rod is attached, rests on two oak uprights and can be raised
by admitting air into an air-cushion, through the central opening of
which passes the chair-suspending rod. As the air enters the air-cushion
it expands and lifts a large wooden disk which, in turn, lifts the iron
cross-bar, raising the chair and weight suspended upon it. At the proper
height and when the stopper has been thoroughly forced into place, two
movable blocks are slipped beneath the ends of the iron cross-bar and
thus the stopper is held firmly in place. The tension is then released
from the air-cushion. This apparatus functionates very satisfactorily,
raising the man or lowering him upon the knife-edges of the balance with
the greatest regularity and ease.

PULSE RATE AND RESPIRATION RATE.

The striking relationship existing between pulse rate and general
metabolism, noted in the fasting experiments made with the earlier
apparatus, has impressed upon us the desirability of obtaining records
of the pulse rate as frequently as possible during an experiment.
Records of the respiration rate