The Every-day Book and Table Book. v. 3 (of 3) / Everlasting Calerdar of Popular Amusements, Sports, Pastimes, Ceremonies, Manners, Customs and Events, Incident to Each of the Three Hundred and Sixty-five Days, in past and Present Times; Forming a Complete History of the Year, Month, and Seasons, and a Perpetual Key to the Almanac

by William Hone

Comets.

Cassini, and after him sir Isaac Newton, by their close observations and accurate calculations respecting the nature and courses of comets, have given certainty to the opinions of the old philosophers; or, to speak with more propriety, they have recalled and fixed our attention upon what had before been advanced by the ancients on these subjects. For, in treating of the nature of these stars, their definitions of them, the reasons they assign for the rarity of their appearance, and the apologies they make for not having yet formed a more exact theory, are all in the very terms that Seneca had already used. In the time of that philosopher, the observations previously made of the returns of comets, were not sufficiently collected to establish the theory of these phenomena. Their appearances were so very rare, that they had not afforded an opportunity to determine, whether their course was regular or not. The Greeks, however, before Seneca’s time, had remarked to the same effect, and were applying themselves to researches of this kind.

Seneca says, that the Chaldeans looked upon comets as planetary bodies; and Diodorus Siculus, in giving an account of the extent of knowledge among the Egyptians, praises them for the application with which they studied the stars and their courses; and remarks, that they had collected, observations very ancient and very exact, fully informing them of the several motions, orbits, stations, &c. of the planets. He adds, that they could foretell earthquakes, inundations, and “the return of comets.”

Aristotle says, that Anaxagoras apprehended comets to be an assemblage of many wandering stars; which, by their approximation, and the mutual blending of their rays, rendered themselves visible to us. This notion, though far from being philosophical, was yet far preferable to that of some great moderns, such as Kepler and Hevelius, who supposed that comets were formed out of air, as fishes are out of water.

Pythagoras, however, who approached very near to the times of Anaxagoras, held an opinion worthy of the most enlightened age. He looked upon “comets as stars, which circulated regularly, though elliptically, about the sun, and which appeared to us only in particular parts of their orbit, and at considerable distances of time.”

Seneca, more than any other, has discussed this subject like a true philosopher. He relates all the different opinions respecting comets, and seems to prefer that of Artemidorus, who imagined, “that there was an immense number of them, but that their orbits were so situated, that, so far from being always within view, they could only be seen at one of the extremities.” He reasons upon this with equal elegance and solidity. “Why should we be astonished,” says he, “that comets, which are so rare a spectacle in the world, have not yet come under certain rules; or that we have not hitherto been able to determine, where begins or ends the course of planets, as ancient as the universe, and whose returns are at such distant intervals? The time will come,” he exclaims, with enthusiasm, “when posterity will be amazed at our ignorance in things so very evident; for what now appears to us obscure, will one day or other, in the course of ages, and through the industry of our descendants, become manifestly clear; but, a small number of years, passed between study and the indulgence of passion, are not of avail for researches so important, as those which propose to themselves the comprehension of natures so remote.”

The moderns have said nothing satisfactory respecting comets, but what is to be found in the writings of the ancients; except what later observations have furnished them with, which Seneca judged to be so necessary, and which only could be collected through a long succession of ages.

The Moon.

The ancients discovered very early, that “the moon had no light of its own, but shone with that which it reflected from the sun.” This, after Thales, was the sentiment of Anaxagoras, and that of Empedocles, who thence accounted not only for the mildness of its splendour, but the imperceptibility of its heat, which our modern experiments confirm: for with all the aid of burning glasses, we have never yet found it practicable to obtain the least warmth from any combination of its rays.

With a telescope, we easily discern in the moon parts more elevated and more bright than others, which are judged to be mountains; and means have been found to measure their elevation. We discern also other parts, lower and less bright, which must be vallies, lying between those mountains. There are other parts, which reflecting less light, and presenting one uniform smooth surface, may therefore be supposed large pieces of water. As the moon, then, has its collections of water, its atmosphere, its mountains, and its vallies; it is thence inferred, that there may also be rain there, and snow, and all the other aerial commotions which are natural to such a situation; and our idea of the wisdom and power of God suggests to us, that he may have placed creatures there to inhabit it.