OP UEEA AND DEINAEY WATEE. 
805 
manner and during short periods. Deaper, Speck, and J. Lehmann found no increase 
in the urea, whilst C. J. Lehmann, Hammond, Beneke, and Beigel found a variable 
increase not exceeding 25 per cent. When much sweating occurred, as it commonly 
did with severe exertion, it was assumed that urea had been lost by the perspiration, in 
accordance with the results obtained by Funke and Meissner. The excretion of urinary 
water varied in the dilferent experiments. VoiT has, I believe, recently ascertained that 
with prolonged exertion a dog did not emit any materially increased quantity of urea — 
a result which will now be shown to correspond with my own preceding and contempo- 
raneous experiments. 
The relation of urea to exertion was determined by the second series of inquiries, 
viz. those made on four prisoners from March 1 to March 26, 1860. 
The treadwheel is a revolving drum, with steps placed at distances of 8 inches upon 
the outside of the cylinder ; and the prisoners are required to turn the wheel downwards 
by stepping upwards. The rapidity of revolution is regulated partly by the weight of 
the prisoners, and partly by a governor, and therefore is not absolutely uniform. The 
prisoners grasp a crossbar, and partly hang by it, and the body is held behind its centre 
of gra\ity. They were engaged in this labour in alternate quarters of an hour, the 
intervening periods being occupied in perfect rest in the sitting posture. The duration 
of this mingled labour and rest was from 7.15 to 8.25 A.M., 10.10 a.m. to 1.50 p.m., and 
3.10 to 5.20 P.M.; so that the total period of actual labour daily was 3^ hours. The 
total ascent per hour of continuous labour was 2160 feet, and per day 1*432 mile. The 
average weight of each man at the end of the inquiry was 105*125 lbs., 108*125 lbs., 
120*5 lbs., and 122*625 lbs. avoirdupois, and of the whole 113*75 lbs.; and therefore 
the number of tons which they lifted 1 foot per day was as follows, upon the data used 
by Professor Haughton : — 
Table XXXI. 
No. of prisoner 
858. 
948. 
1040. 
1041. 
Average of all. 
Weight in lbs 
Tons, 1 foot daily 
105*125 
354*81 
108*125 
356*76 
120*5 
406*56 
122*625 
413*89 
113*75 
383*9 
Hence the average labour of each man was represented by liftmg 384 tons through 
1 foot per day, and this was exacted on alternate days only, on Tuesday, Thursday, and 
Saturday, whilst Sunday was a day of almost unbroken rest. There were during the 
inquiry ten days of treadwheel labour, ten of very light labour, and four of perfect rest. 
Their daily dietary was as follows : — 
20 oz. of excellent brown bread, one pint of cocoa, one pint of oatmeal gruel, 6 oz. of 
cooked meat without bone (ij oz. lean and l^oz. fat), 8oz. of boiled potatoes, about 
1 oz. of salt, 10 oz. of water at midday, at 2 p.m. with dinner, and at 4 p.m. No. 1040 
had 6f oz. of bread daily. All the food was eaten, and the quantity of salt was regu- 
lated to three-quarters of an ounce daily on March 7. Thus the average solid food was 
34 oz. (plus 6f oz. bread for 1040, and the ingredients in the gruel and cocoa in all the 
5 Q 2 
