METHODS AND APPARATUS 31 
ROUTINE OF EXPERIMENTS. 
Rest experiments. — The majority of the work experiments were preceded 
each morning by an experiment in which the respiratory exchange was 
determined while the subject lay quietly upon a couch. Many work experi- 
ments were also followed by similar experiments of several periods each. 
Since the results of these rest experiments were used as the base-line, particu- 
lar care was taken to secure uniform conditions. The subject came to the 
laboratory between 7 h 30 m and 7 h 45 m a.m., and as no food had been 
taken for 12 hours, he was in the post-absorptive condition. After putting 
on his riding clothes he lay down on the couch with a blanket over him and 
remained quiet for at least half an hour, during which time the pulse-rate 
continually decreased until a minimum was reached. The subject was in- 
structed to lie very quietly during the period, without moving a muscle but 
also without rigidity. After he had become thoroughly quieted down and 
the pulse-rate had reached its normal resting level, the mouthpiece was in- 
serted and the noseclip attached; the subject then breathed room-air for 
several minutes into and out of the mouthpiece. At the end of a normal 
expiration the valve was turned, connecting the subject with the main 
ventilating-current, and the experiment continued in this manner for about 
15 minutes. At the end of the experimental period the valve was again 
turned so that the subject was cut off from the air-current, the valve being so 
deflected as to connect him with room-air. During the entire experimental 
period the amount of oxygen admitted was noted on a carefully calibrated 
gas-meter immersed in water and the temperature of the gas-meter, the bar- 
ometer, and the pulse-rate were regularly recorded throughout the experi- 
ment. 
In connection with the respiration experiments carried out in this labora- 
tory, it is a part of the regular routine to secure graphic records of any extrane- 
ous muscular activity by means of pneumographs placed around either the 
chest or the thighs, and sometimes both pneumographs are used. In the first 
experiments with this bicyclist, graphic records of the degree of muscular 
rest were obtained in this way. It was soon found, however, that this particu- 
lar subject was unusually quiet, and as we were convinced of the absence of 
muscular activity in all rest experiments with this subject, and further, as the 
application of the apparatus seemed to cause him some annoyance, the use of 
the pneumograph was abandoned. 
Sitting experiments. — In the sitting experiments with the professional 
bicyclist, the subject sat quietly upon the ergometer as usual, the feet resting 
on the pedals; there was, however, no rotation of the pedals. In experiments 
with some of the other subjects, the feet rested lightly upon wooden blocks or 
upon an iron foot-rest attached to the front fork of the apparatus, the posi- 
tion being otherwise the same as for experiments with the professional athlete. 
But few of these sitting experiments were made, as the subjects found the 
position very uncomfortable. The general routine followed was the same as 
that in the rest experiments. 
No-load experiments. — In certain experiments the subject rode the er- 
gometer without load, the pedals being rotated by the feet or by an electric 
motor. It was found in these experiments that there was considerable lateral 
motion of the subject's head; consequently it was necessary to use the special 
