BODILY WORK AND WASTE. 
153 
fessor Haughton, M.D., F.B.S., of Trinity College, Dublin) — 
have thrown a good deal of light upon this obscure and difficult 
subject. With the view of giving our readers a general idea 
of the relations of bodily work to bodily waste, we will briefly 
recapitulate the nature of these researches. 
We have before stated that the total amount of urea which 
is formed in the body of a healthy man of 150 lb. weight, per 
diem , fluctuates from 400 to 630 grains. Of this amount Dr. 
Haughton calculates, from data to which it is impossible for us 
here to refer, that 300 grains are the result of that division of 
work to which we have above given the designation vital. 
Hence it follows that each pound of man requires an amount 
of daily waste which is represented by 2 grains of urea merely 
to keep it alive, and prevent it from becoming subject to the 
ordinary chemical laws of inert matter. 
But if this 300 grains of urea represents a certain amount of 
bodily waste, that bodily waste in its turn represents a certain 
amount of work done, or force expended; and to estimate 
what that work is, we must find out the equivalent, in some 
definite and easily calculable form of work, of a definite quan- 
tity, say one grain of urea. This Dr. Haughton has done. 
But before stating the results at which he has arrived on this 
point, it should, perhaps, be mentioned, for the benefit of those 
to whom this subject may be entirely new, that it is usual to 
calculate all varieties of mechanical force in terms of a single 
unit, and that unit is the force which is required to raise one 
ton avoirdupoise one foot from the earth. For instance, a man 
who walks twenty miles a day can be shown in so doing to 
perform an amount of mechanical work which, if applied in 
another way, would raise a weight of 150 lb., i. e ., about the 
weight of his own body, one mile in the air. Again, the ordi- 
nary daily work of a street paviour, who works ten hours 
a day, and whose occupation consists in lifting, at definite 
intervals, a rammer weighing 5-i- stone, is equivalent, if applied 
as before mentioned, to lifting a weight of one ton 352 feet in 
the air. In this way the foot-ton, as it is called — i.e ., one ton 
lifted one foot — becomes the unit of measurement of dynamical 
; force generally. 
How, let us recur to the consideration of the force which is 
expended in the daily waste of 300 grains of urea. From a 
series of elaborate calculations Dr. Haughton estimates that 
the mechanical equivalent of this quantity of urea is one ton 
lifted 769 feet, or 769 foot-tons. That is to say, this enor- 
mous force — a force which is more than equal to that 
expended by two street paviours during a hard day's work, is 
used up in merely keeping a man of 150 lb. weight alive for 
the same period. We may put the same fact in another point 
