infallible calculators as Messrs. Tyndall and Thomson I can easily
excuse for any airs they may give themselves. They must be of an order
much higher than that of ordinary mortals like us!"

"I would not answer myself for the accuracy of such intricate problems,"
quietly observed Barbican; "but there is no doubt whatever regarding one
fact: motion suddenly interrupted always develops heat. And this has
given rise to another theory regarding the maintenance of the Sun's
temperature at a constant point. An incessant rain of bolides falling on
his surface compensates sufficiently for the heat that he is
continually giving forth. It has been calculated--"

"Good Lord deliver us!" cried Ardan, putting his hands to his ears:
"here comes Tyndall and Thomson again!"

--"It has been calculated," continued Barbican, not heeding the
interruption, "that the shock of every bolide drawn to the Sun's surface
by gravity, must produce there an amount of heat equal to that of the
combustion of four thousand blocks of coal, each the same size as the
falling bolide."

"I'll wager another cent that our bold savants calculated the heat of
the Sun himself," cried Ardan, with an incredulous laugh.

"That is precisely what they have done," answered Barbican referring to
his memorandum book; "the heat emitted by the Sun," he continued, "is
exactly that which would be produced by the combustion of a layer of
coal enveloping the Sun's surface, like an atmosphere, 17 miles in
thickness."