C.--as near as possible to that
of the inner surface of the walls and windows. A careful use of the
thermometer indicated that the metallic surface of the former was now
nearly zero C., or 32 deg. F. The inner surface of the windows was somewhat
colder, showing that the crystal was more pervious to heat than the
walls, with their greater thickness, their outer and inner lining of
metal, and massive interior of concrete. I directed a current from the
thermogene upon either division of the garden, hoping thus to protect
the plants from whatever injury they might receive from the cold.
Somewhat later, perceiving that the drooping still continued, I
resolved upon another experiment, and arranging an apparatus of copper
wire beneath the soil, so as to bring the extremities in immediate
contact with their roots, I directed through these wires a prolonged
feeble current of electricity; by which, as I had hoped rather than
expected, the plants were after a time materially benefited, and to
which I believe I owed it that they had not all perished long before
the termination of my voyage.
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