The moment of friction of this pivot is at first almost C, inappreciable from the extreme smallness of the T radius of the circles of contact of the ball and cups, but, as they wear, that radius and the moment of friction increase.
This is an inappreciable distance when compared with the diameter of the sun, which is nearly a million of miles, but the significance for our present purpose depends upon the fact that this contraction is always taking place.
It seems, however, most likely that the periods of time required for such changes are immense and that the changes accomplished in only a century or two are absolutely inappreciable.
Yet notwithstanding this enormous effect in iron, the action of a current upon nickel and cobalt turned out to be almost inappreciable.
The total heat with which we are actually concerned in the working of a steam engine is the total heat as here defined, and not the total heat as defined by Regnault, which, however, differs from (E+pv) only by a quantity which is inappreciable in ordinary practice.