had caused so much commotion in Randolph's room on the
fatal day. Hester Dyett would have been able to notice and bring at
least one of the apertures forward in evidence, but she fainted before
she had time to find out the cause of her fall, and an hour later it
was, you remember, Randolph himself who bore her from the room. But
should not the aperture in the top floor have been observed by the
class? Undoubtedly, if its position was in the open space in the middle
of the room. But it was not observed, and therefore its position was
not there, but in the only other place left--behind the apparatus used
in demonstration. That then was _one_ useful object which the
apparatus--and with it the elaborate hypocrisy of class, and speeches,
and candidature--served: it was made to act as a curtain, a screen. But
had it no other purpose? That question we may answer when we know its
name and its nature. And it is not beyond our powers to conjecture this
with something like certainty. For the only "machines" possible to use
in illustration of simple mechanics are the screw, the wedge, the
scale, the lever, the wheel-and-axle, and Atwood's machine. The
mathematical principles which any of these exemplify would, of course,
be incomprehensible to such a class, but the first five most of all,
and as there would naturally be some slight pretence of trying to make
the learners understand, I therefore select the last; and this
selection is justified when we remember that on the shot being heard,
Randolph leans for support on the "machine," and stands in its shadow;
but any of the others would be too small to throw any appreciable
shadow, except one--the wheel, and-axle--and that one would hardly
afford support to a tall man in the erect position. The Atwood's
machine is therefore forced on us; as to its construction, it is, as
you are aware, composed of two upright posts, with a cross-bar fitted
with pulleys and strings, and is intended to show the motion of bodies
acting under a constant force--the force of gravity, to wit. But now
consider all the really glorious uses to which those same pulleys may
be turned in lowering and lifting unobserved that "ball of cotton"
through the two apertures, while the other strings with the weights
attached are dangling before the dull eyes of the peasants. I need only
point out that when the whole company trooped out of the room, Randolph
was the last to leave it, and it is not now difficult to conjectu