it had now fallen to 4° 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° 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.
It would be mere waste of space and time were I to attempt anything like a journal of the weeks I spent in the solitude of this artificial planet. As matter of course, the monotony of a voyage through space is in general greater than that of a voyage across an ocean like the Atlantic, where no islands and few ships are to be encountered. It was necessary to be very frequently, if not constantly, on the look-out for possible incidents of interest in a journey so utterly novel through regions which the telescope can but imperfectly explore. It was difficult, therefore, to sit down to a book, or even to
