he went
forward with his. In a few days an opportunity was given him for
actually trying it. The result, though rather doubtful, seemed to
be that the ball was located where the surgeons supposed it to be.
When the autopsy showed that their judgment had been at fault,
Mr. Bell admitted his error to Dr. Woodward, adding some suggestion
as to its cause. "Expectant attention," was Woodward's reply.

I found in the basement of the house an apparatus which had been
brought over by a Mr. Jennings from Baltimore, which was designed
to cool the air of dairies or apartments. It consisted of an iron
box, two or three feet square, and some five feet long. In this
box were suspended cloths, kept cool and damp by the water from
melting ice contained in a compartment on top of the box. The air
was driven through the box by a blower, and cooled by contact with
the wet cloths. But no effect was being produced on the temperature
of the room.

One conversant with physics will see one fatal defect in this
appliance. The cold of the ice, if I may use so unscientific an
expression, went pretty much to waste. The air was in contact,
not with the ice, as it should have been, but with ice-water, which
had already absorbed the latent heat of melting.

Evidently the air should be passed over the unmelted ice.
The question was how much ice would be required to produce the
necessary cooling? To settle this, I instituted an experiment.
A block of ice was placed in an adjoining room in a current of
air with such an arrangement that, as it melted, the water would
trickle into a vessel below. After a certain number of minutes
the melted water was measured, then a simple computation led to a
knowledge of how much heat was absorbed from the air per minute by
a square foot of the surface of the ice. From this it was easy to
calculate from the known thermal capacity of air, and the quantity
of the latter necessary per minute, how many feet of cooling surface
must be exposed. I was quite surprised at the result. A case of
ice nearly as long as an ordinary room, and large enough for men
to walk about in it, must be provided. This was speedily done,
supports were erected for the blocks of ice, the case was placed at
the end of Mr. Jennings's box, and everything gotten in readiness
for directing the air current through the receptacle, and into the
room through tubes which had already been prepared.

It happened that Mr. Jennings's box was