[63] To some this may appear to be a mere truism. In reality it is far
from being so. If two globes of equal mass were each of the same exact
temperature throughout, they might yet have very unequal total quantities
of heat. If one were of water, for instance, and the other of iron or any
other metal, the former would have far the larger supply of heat; for more
heat is required to raise a given weight of water one degree in
temperature, than to raise an equal weight of iron one degree; and water
in cooling one degree, or any number of degrees, would give out more heat
than an equal weight of iron cooling to the same extent.