CHAP. XXI. MORE ABOUT THE HARVEST-MOON, AND ABOUT THE HUNTER'S MOON. My little readers must be grown bigger, and better acquainted with the science of astronomy, before it can be of any use to attempt explaining to them those niceties concerning the changes, -not of the moon,-but of its orbit, which minutely account for what I have just been speaking of; but I may mention, even now, that if it were not for these changes in the position of the moon's orbit, the moon, as usual, would rise exactly fifty minutes later every night or evening; because the moon moves from east to west in its orbit about thirteen degrees every day; a space which it overruns in the fifty minutes here referred to. Whereas, from the autumnal change of position in the moon's orbit, it comes to pass, that, at times, the moon as it appears to us, is so long as an hour and seventeen minutes, (or seventy-seven minutes,) and at other times so quick as seventeen minutes, in overrunning the thirteen degrees; and is, therefore, at times seventy-seven minutes, and at other times only seventeen minutes,-in performing the same journey. Now, it is because the change, for several successive evenings, at the times of the full moons that I speak of, is really no more than the unusually short period of seventeen minutes; that therefore the time appears to be the same, or to have no change whatever. But there is also another variation, and to this, too, I have already alluded. At one period in the course of the changes of the position of the moon's orbit, the Harvest Moon, as well as the Hunter's Moon, will rise, upon the successive evenings, more nearly at the same time than at other periods; and, at this period of greatest uniformity, the Harvest Moons are said to be those most beneficial to the husbandman. When, however, nine years, and a hundred and twelve days, have next elapsed, the Harvest Moons, for another period, fail to rise so nearly at the same time upon each evening; and it is then that they are said to be those the least beneficial. Astronomers, as I have said, are able to tell us of them before they come, as well as to say when they formerly happened. Thus, as in the instances following, some past, some coming, here are years in which the Harvest Moons were or will be least beneficial-and in which years, also past or coming, they were or will be most so. The years 1812, 1831, and 1849, are set down for years in which the Harvest Moons When are the Harvest Moons said to be most beneficial? Are their appearances and returns capable of nice calculation? |