he space between the 10-inch and the 12-inch marks, so that only
_one_ pint of water can be accommodated there. What becomes of the other
pint? Why, if there were no more cylinder, it would lie on the top, and
fill the jar up to the 13-inch mark. But unfortunately----Shade of
Newton!" he exclaimed, in sudden accents of terror. "When _does_ the
water stop rising?"

A bright idea struck him. "I'll write a little essay on it," he said.

* * * * *

_Balbus's Essay._

"When a solid is immersed in a liquid, it is well known that it
displaces a portion of the liquid equal to itself in bulk, and that the
level of the liquid rises just so much as it would rise if a quantity of
liquid had been added to it, equal in bulk to the solid. Lardner says,
precisely the same process occurs when a solid is _partially_ immersed:
the quantity of liquid displaced, in this case, equalling the portion of
the solid which is immersed, and the rise of the level being in
proportion.

"Suppose a solid held above the surface of a liquid and partially
immersed: a portion of the liquid is displaced, and the level of the
liquid rises. But, by this rise of level, a little bit more of the solid
is of course immersed, and so there is a new displacement of a second
portion of the liquid, and a consequent rise of level. Again, this
second rise of level causes a yet further immersion, and by consequence
another displacement of liquid and another rise. It is self-evident that
this process must continue till the entire solid is immersed, and that
the liquid will then begin to immerse whatever holds the solid, which,
being connected with it, must for the time be considered a part of it.
If you hold a stick, six feet long, with its end in a tumbler of water,
and wait long enough, you must eventually be immersed. The question as
to the source from which the water is supplied--which belongs to a high
branch of mathematics, and is therefore beyond our present scope--does
not apply to the sea. Let us therefore take the familiar instance of a
man standing at the edge of the sea, at ebb-tide, with a solid in his
hand, which he partially immerses: he remains steadfast and unmoved, and
we all know that he must be drowned. The multitudes who daily perish in
this manner to attest a philosophical truth, and whose bodies the
unreasoning wave casts sullenly upon our thankless shores, have a truer
claim to be called the martyrs of science th