In this latitude all observers may at times notice two distinct forms of the aurora. The one, as we often see it, has a cloud-like appearance, with a soft radiance permeating it, and seems a vast, irregular patch of mellow light, ever changing, and at times showing a slightly reddish or purple tinge. It is more frequently seen near the northern horizon, having the form of a beautiful arch, the ends of the segment apparently resting on the horizon, and the middle, or crown, a few degrees above it. The other takes the form of streamers, reaching far up toward the zenith. Gently curved, like the celestial sphere on which they are projected, they are not stationary, but almost constantly in motion, but soon resuming their former position, spreading themselves out like immense flags, with their numerous silken folds, ever dancing, quivering, undulating, as if stirred by some gentle breeze, though all else seems in calm repose. To say that the phenomena are electrical, would, probably, not be the whole truth, though evidence is not wanting that the aurora is in some way connected with the electricity and magnetism of the earth and its atmosphere. Practical telegraphists testify that during a brilliant display of “northern lights” such strong, irregular currents of electricity pass along the wires that it is difficult to send a dispatch; at other times the currents are so strong that they can communicate without the battery. There is, perhaps, about as much against the theory of a purely electrical origin, as in its favor, and, on the whole, we conclude that the Aurora Borealis is one of the things respecting which modern observations have suggested more difficulties than modern science is yet able to explain. HOME STUDIES IN CHEMISTRY AND PHYSICS. BY PROF. J. T. EDWARDS, D. D. Director of the Chautauqua School of Experimental Science. FIRE.—PHYSICAL PROPERTIES. Clearness, accuracy, and brevity are the essentials of good definition. That it is no easy task to combine these, every teacher realizes. Perhaps it is near the truth to say that fire is that operation in nature which at the same time evolves heat and light. The _operation_ is, at the present time, supposed to be a certain vibration of ethereal or more solid substances. All matter is in motion. Whence this motion was first derived no philosopher can tell, unless he goes back to that primal source of both matter and motion, which in the beginning created the heavens and the earth, and said, “Let there be light, and there was light.” Prof. James Dwight Dana[1] declares that the first act of creative power must have been heralded throughout the universe by a flash of light. Thus the geologist unites with the scriptural narrator, in the statement that light and heat belonged to the first day of creation, although scoffers for a long time ridiculed the idea that light could exist without the sun.