thin coat of wax. The bar thus prepared was placed under a ram, of known
weight, P, which was raised to a height, H, where it was automatically
released so as to expend upon the bar the whole quantity of work _T=PH,_
between the two equal faces of the ram and the anvil. A single shock
sufficed to melt the wax upon a certain zone and thus to limit, with
great sharpness, the part of the lateral faces which had been raised
during the shock to the temperature of melting wax. Generally the zone
of fusion imitates the area comprised between the two branches of an
equilateral hyperbola, but the fall can be so graduated as to restrict
this zone, which then takes other forms, somewhat different, but always
symmetrical. If A is the area of this zone, b the breadth of the bar, d
the density of the metal, c its capacity for heat, and t-t0 the excess
of the melting temperature of wax over the surrounding temperature, it
is evident that, if we consider A as the base of a horizontal prism
which is raised to the temperature t, the calorific effect may be
expressed by:

Ab x d x C(t-t0);

and on multiplying this quantity of heat by 425 we find, for the value
of its equivalent in work,

T' = 425 AbdC(t-t0).

On comparing T' to T we may consider the experiment as a mechanical
operation, having a minimum of:

T'/T = (425/PH)AbdC(t-t0).

After giving diagrams and tables to illustrate the geometrical