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 also have an interest, though not of as
great importance. In order to obtain the pulse rate, we attach a Bowles
stethoscope over the apex beat of the heart and hold it in place with a
light canvas harness. Through a long transmission-tube passing through
an air-tight closure in the walls of the calorimeter it is possible to
count the beats of the heart without difficulty. The respiration rate is
determined by attaching a Fitz pneumograph about the trunk, midway
between the nipples and the umbilicus. The excursions of the tambour
pointer as recorded on the smoked paper of the kymograph give a true
picture of the respiration rate.
Of still more importance, however, is the fact that the expansion and
contraction of the pneumograph afford an excellent means for noting the
minor muscular activity of a subject, otherwise considered at complete
rest. The slightest movement of the arm or the contraction or relaxation
of any of the muscles of the body-trunk results in a movement of the
tambour quite distinct from the respiratory movements of the thorax or
abdomen. These movements form a very true picture of the muscular
movements of the subject, and these graphic records have been of very
great value in interpreting the results of many of the experiments.
ROUTINE OF AN EXPERIMENT WITH MAN.
Public-domain text, read in full here on John Shaqi.
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