ON PRISON DIET AND DISCIPLINE. 59 



the urea produced would not be eliminated within that period, and hence we 

 cannot take this as indisputable evidence of the effect of tread wheel -labour. 

 The variations above referred to were also, in part at least, due to the varia- 

 tion in the quantity of urinary water which was secreted during that period ; 

 and it is just possible that, notwithstanding every care, the bladder might not 

 have been completely emptied on each occasion. 



The total daily excretion of urea was the least on the Sunday, greater on 

 the days of light labour, and the greatest on days of treadwheel-labour, on 

 which occasions the average quantities were 494<, 512, and 528 grains, 

 giving a daily increase on tread wheel-days of 16 grains over that of days of 

 light labour, and of 34 grains over that of perfect rest. There were some di- 

 .versities in the results, owing, apparently, to the fact that on two occasions 

 the elimination of the urea due to the treadwheel-days was in part deferred 

 until the next day, when there were remarkable meteorological disturbances, 

 and thus gave the appearance of greater elimination on the days of light or 

 of no labour. From this cause one of the cases gave an average de- 

 crease of 51 grains of urea on the days of treadwheel-labour, but in the 

 other three prisoners the increase with labour was 37, 59, and 21 grains 

 daily. The largest increase on the treadwheel-days was Hi grains, and the 

 largest decrease 100 grains per day. 



Urinary Water. — The quantity of urinary water evolved was, on the total 

 average, lO'-t per cent, greater on tread wheel than on other days, viz., 74'7 

 and 67"7 fl. ozs., and the same relation held good in each of the cases. 

 Thus 



Register No. of Prisoner. On Treadwheel days. On other days. 



ozs. ozs. 



858 79-4. 73-15 



948 82-87 70-8 



1040 67-9 63-8 



1041 68-9 62-9 



The quantity of fluid drank was the same on each day, and the amount 

 lost by perspiration was much greater on treadwheel-days than on other 

 days ; and hence the blood and tissues must have lost considerably more fluid 

 with great labour than occurs with rest. 



Chloride of Sodium. — The evolution of chloride of sodium was very 

 great, owing to the large quantity taken with food, but was somewhat less 

 on treadwheel days than on other days, viz., 509 and 520 grains. When 

 the quantity of chloride of sodium taken with the food was diminished, the 

 same relation was still maintained, but in a less degree, viz., 432 and 437 

 grains, ^here was much variation in the results. 



Hence, from all these inquiries, it follows that there is an increased 

 elimination of urea and urinary water with treadwheel-labour, but the 

 former is much less and the latter much more than we should have expected. 

 Neither of them are efficient measures of the true effect of exertion. 



FcBces.— The determination of the daily evacuation of taeces was rendered 

 difficult from the habit of one of the prisoners to have an evacuation only on 

 alternate days, and the only method by which we could make an approxima- 

 tion to the daily evacuation was to divide the quantity on alternate days into 

 two equal parts, and reckon one part on the day on which no evacuation 

 occurred. The faeces were also placed under the date of the preceding day, 

 as they clearly were due to the conditions of that day. The following are 

 the principal facts educed : — 



1. The average weight of the faeces daily was double of that found in 



