206 THE LAND OF PLUCK

“Did it?” she said with solemn surprise.

As the precious girl—please don’t mind my speaking
in this way of my little wife, for, the fact is, we have been
marrigd but two years, and she is just twenty to my twenty-
five,

 

as the precious girl evidently did not expect an
answer to her question, I took up the book again and read:

“By attending to the center of gravity of the bodies around us
on the earth, we are enabled to explain why, from the influence
of gravity, some of them are stable, or firmly fixed, others tot-
tering, others falling. * * * The line of a plummet hanging
from the center of gravity is called the line of direction of the
center, or that in which it tends naturally to descend to the
earth,

“You remember, Lily,” said I, interrupting myself,
“the law we read in Gale yesterday:

“While the line of direction falls within the base wpon which
the body stands, the body cannot upset; but if the line fall
beyond the base, the body will tumble.”

Then, taking a pencil and note-book from my pocket, I
made a picture of a coach tilted by a great stone in such
a way that a perpendicular line drawn from its center of
gravity fell beyond the base of the coach, that is, outside of
the point where its wheels touched the ground, and she
saw at a glance, with a little womanly shiver, that the
coach must upset.

“Oh, yes, I understand it now, perfectly,” she exclaimed,
quite pleased.

So I read on, as Dr. Arnott proceeded to tell us how to
find the center of gravity of any object, and to explain in