The twentieth century atlas of popular astronomy comprising in twenty-two plates a complete series of illustrations of the heavenly bodies - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ...and settings of the moon are given, we will find that the daily retardation of rising varies greatly. It is sometimes as much as an hour and a quarter, at other times less than half an hour. This arises from the irregular motion of the moon in its orbit, its motion eastwards being greatest when in perigee, and least when in apogee. The angle between the horizon and the ecliptic is also constantly changing, and this has also a large effect on the difference in the daily retardation. From these considerations we can arrive at the explanation of the Harvest Moon. It will be seen from the calendar that in each month the daily retardation of rising goes through all its variations. If the risings for several months are examined, it will be seen that the greatest or least retardation does not always correspond to the same phase of the moon. In the case of the full moon nearest to the 21st of March the daily retardations are greater for a few days before and after full moon than they are in the rest of the month. Again, at the full moon nearest to the 23rd of September the daily retardations of rising are less about full moon than in the rest of the month. The September full moon, therefore, rises for several days in succession soon after sunset, and enables the agriculturist to continue the important task of gathering in his harvest after the sun has set. The reason of this will become apparent after a few minutes' study of a celestial globe. Set the globe for the latitude of the place of observation, say Edinburgh, 56 N. This is done by slipping the brass meridian round till the pole of the sky is 56 above the north horizon. Now find the sun's place amongst the stars on the 21st of March--namely, the first point of Aries, the intersection of the ecliptic and equa...