of Edinlurgh, Session 1883-84. 
957 
apparatus and energy employed in its exploitation and movement — 
in short, of price, labour, capital, &c., and so on, have all to be dis- 
cussed. ]\Iuch of this is done in ordinary treatises — the primary 
and essential physical problem, however, remains (untouched by 
economists, save Mr Jevons almost alone) — that (1) of estimating 
the total quantity of energy stored at our disposal in this form per 
area of territory; (2) the gross and net quantity utilised per unit 
time ; (3) the details of its utilisation and ultimate dissipation. 
Thus physical precision can be approximately reached : measure- 
ment in terms of units of energy as well as of units of weight is 
practicable : and, this physical conception once introduced, its exten- 
son to all processes must be attempted. For the treatment of this 
only one other consideration need be pointed out — the possibility of 
expressing the labour of the producer-automata, just as we do that 
of the ordinary machines with which they are so largely inter- 
changeable : the horse-power of an engine is easily translatable into 
man-power — might, indeed, always have been so expressed; this 
granted, the conception of a man-daij (of course averaging the same 
for labourers of a given community at given time, though vastly 
differing according to the age of energy) and its multiples (man-year 
— man-life) with the higher multiples of these can all be approxi- 
mately stated. Producers and machines are, in short, not only 
interchangeable but commensurable. 
Against the gross product of exploitation must be set the quantity 
of matter and energy expended in its production, together with the 
quantity wasted through the imperfection of our processes, plus all 
losses through other agencies. The gross product is expressed by the 
rectangle of exploitation in the upper table, the deduction for losses 
is indicated by the uppermost portion cut off from it, that for cost 
of production by the lower dotted portion, the remainder is the net 
product. Upon this the processes of manufacture and movement 
have to operate ; and their cost and loss being similarly deducted, 
the remainder is the net amount of ultimate product. 
In the hypothetical graphic statistic of the table, the net amount 
of ultimate product may seem unwarrantably small in proportion to 
the gross amount of potential product ; this smallness is intended to 
suggest the vast losses of energy and^ matter, often many times 
exceeding the product, due to the imperfection of our processes. 
