710 
DE. E. SmTH ON THE CHEMICAE 
On July 15, with a temperature of 75^°, whilst walking at two miles per hour, I 
expired 18'1 grs. of carbonic acid per minute, with a rate of respiration of llg^ 
pulsation 90 per minute, and with 799 cubic inches of inspired air per minute. 
At three miles per hour the carbonic acid was increased to 25-83 grs., the air to 
1027-5 cubic inches, and the rate of respiration to 16 per mmute. I did not attempt 
a greater speed ; for it required closer attention than I could give to the speed and the 
apparatus at the same time to maintain a uniform rate of more than three miles per 
hour. . j? j • 
Thus, taking as a basis of comparison the system at rest and without food, m the 
sitting posture, at the same hour, viz. 7-44 grs. of carbonic acid per minute, the effect of 
walking at two miles per hour was 2-5 times as great, and at thi-ee miles per hour 3 5 
times. There is a curious progression in the relation of carbonic acid to the inspii-ed air 
under these different conditions, as follows, taking 1 gr. of carbonic acid as the unit of 
comparison : viz. in rest, sitting, and fasting, 1:49-6 cubic inches ; walking at two miles 
per hour, 1:44-1 cubic inches; at three miles per hour-, 1:39-7 cubic inches— a pro- 
gressive increase in the ratios of nearly one-ninth of the basis quantity. 
2. The Treadwheel. 
The treadwheel is a kind of exertion which consists in lifting the body a gh en height 
in a given time, from the steps of a wheel turning downwards, and holding it m a 
position in which its centre of gravity is anterior to its perpendicular central hne. ^ My 
experiments have been made in many county gaols, but in only that at Coldbath Fields 
have I determined the quantity of carbonic acid evolved during this kind of exertion. 
I am under obligation to the Governor and Visiting Justices for much coui-tesy and 
assistance. 
There are not any similar inquiries on record ; but in reference to raising the bod) 
through a given space at given times, Lavoisiee has stated the quantity of oxygen which 
is consumed, and also that the increased rate of pulsation is dhectly as the weight mul- 
tiplied by the height, if the effort is an easy one. 
The influence of the treadwheel has been determined by thi’ee experiments, as 
recorded in Table VIII. On October 8, with a low normal state of the respu-atiou. 
I expired 43-36 grs. of carbonic acid per minute whilst upon the wheel; and on 
October 9 the quantity was 42-9 grs. per minute. On each occasion the pulse was 
150 per minute, and the rate of respiration 22 and 21 per minute respectively. On 
October 22, in the afternoon, after having eaten the prisoners’ dinner of brown bread 
and soup, the quantity was 48-66 grs. per minute, with a pulsation of 150, and respi- 
ration 20 per minute. In all the inquiries I worked the wheel fifteen minutes at a 
time. In the two former I collected the carbonic acid during three nimutes, aftei 
having been upon the wheel five minutes, and again durmg the last two of the fifteen 
minutes ; but in the last inquiry I collected it in the last two of each five of the fifteen 
minutes. Thus the average in the first two is derived from five minutes, and in the last 
