Page:Popular Science Monthly Volume 29.djvu/767

Rh the orbit fifteen degrees along the ecliptic—would not leave the group such a compact train as we found it in 1866. If this result is at all possible, it is because the total action is scattered over so many centuries. But it seems more probable that the fragments are parting more rapidly from the comet than we have assumed, and that long before the complete ring is formed the groups become so scattered that we do not recognize them, or else are turned away so as not to cross the earth's orbit.

Comets by their strange behavior and wondrous trains have given to timid and superstitious men more apprehensions than have any other heavenly bodies. They have been the occasion of an immense amount of vague and wild and worthless speculation by men who knew a very little science. They have furnished a hundred as yet unanswered problems which have puzzled the wisest. A world without water, with a strange and variable envelope which takes the place of an atmosphere, a world that travels repeatedly out into the cold and back to the sun, and slowly goes to pieces in the repeated process, has conditions so strange to our experience, and so impossible to reproduce by experiment, that our physics can not as yet explain it. Yet we may confidently look forward to the answer of many of these problems in the future. Of those strange bodies, the comets, we shall have far greater means of study than of any other bodies in the heavens. The comets alone give us specimens to handle and analyze. Comets may be studied, like the planets, by the use of the telescope, the polariscope, and the spectroscope. The utmost refinements of physical astronomy may be applied to both. But the cometary worlds will be also compelled, through those meteorite fragments with their included gases and peculiar minerals, to give up some additional secrets of their own life and of the physics of space to the blow-pipe, the microscope, the test-tube, and the crucible.



E may define history as the narration of events in their causal relations. Nowhere does this definition find more instructive application than in the evolution of education. We see here, and with unmistakable plainness, the effect of distinctive contributions from the sides of our common nature. The stages in the history of education are natural growths; each movement in the unfolding was a necessity. Our present paper will consider many facts which, by themselves, would appear so unnatural, so out of relation to modern 