952 
Proceedings of the Royal Society 
ing out, and its energy running down — and this waste which its 
functions involve must he repaired by obtaining from the environ- 
ment periodic supplies of new matter and energy. From the 
destructive forces of the environment it must similarly be pro- 
tected ; and so on. From the present standpoint then it is not 
merely analogous to, but identical with a mechanism ; “ producers ” 
are those automata devoted to the acquisition of matter and energy 
from the environment; while all are ‘‘consumers,” and in this 
aspect in wonderfully similar degree. 
Without ignoring the historic services of the physiocratic school, 
the application of the conceptions of modern physics to economics 
may be fairly said to date from Professor Tait’s discussion of the 
Sources of Energy in Nature, published about twenty years ago (see 
N07dh British Revieiv^ vol. xl., also Balfour Stewart on Heat, &c.). 
The subject has been developed to some extent by other physicists, 
as Siemens, Thomson, &c., but seldom by economists, with the dis- 
tinguished exception of Professor Stanley Jevons, whose investi- 
gations on the coal supply, and whose hypothesis of the correlation 
of sun spots and commercial crises, are both essentially from the 
present point of view. 
Starting then from a given territory at given time, and enumerat- 
ing the utilisable sources of matter and energy in the form given by 
Tait, and adopted in the Glassification of Statistics (p. 13, table B), 
we may proceed to systematise the phenomena of production and 
consumption, and this is most conveniently done in diagrammatic 
form. Let us arrange these facts — which should of course aim at 
statistical precision- — in a first column. (Op. cit. and fig. 3.) 
After these we may further enumerate the sources of matter not 
used for the sake of its potential energy, but on account of its other 
properties (physical, chemical, &c.). This matter and energy are as 
yet mere raw material or potential products, and require develop- 
ment into ultimate products ; the requisite processes of production 
having generally three stages — exploitation, manufacture, and move- 
ment, the last including transport and exchange ; for exchange 
from our present point of view is simply part of the process of 
movement of the product from the place of production to that oi 
consumption. That proportion of potential products (large in com- 
plex societies) which has to be converted into apparatus used in 
