To conceive the reason of this phenomenon, it may first be considered, that the moon is always opposite to the sun when she is full; that she is full in the signs Pisces and Aries in our harvest months, those being the signs opposite to Virgo and Libra, the signs occupied by the sun about the same season; and because those parts of the ecliptic rise in a shorter space of time than others, as may easily be shown and illustrated by the celestial globe: consequently, when the moon is about her full in harvest, she rises with less difference of time, or more immediately after sun-set, than when she is full at other seasons of the year.
In our winter, the moon is in Pisces and Aries about the time of her first quarter, when she rises about noon; but her rising is not then noticed, because the sun is above the horizon. In spring, the moon is in Pisces and Aries about the time of her change; at which time, as she gives no light, and rises with the sun, her rising cannot be perceived. In summer, the moon is in Pisces and Aries about the time of her last quarter; and then, as she is on the decrease, and rises not till midnight, her rising usually passes unobserved. But in autumn, the moon is in Pisces and Aries at the time of her full, and rises soon after sun-set for several evenings successively; which makes her regular rising very conspicuous at that time of the year.
| L | M | L | M | L | M | L | M |
|---|---|---|---|---|---|---|---|
| 1790 | 1798 | 1807 | 1816 | 1826 | 1835 | 1844 | 1853 |
| 1791 | 1799 | 1808 | 1817 | 1827 | 1836 | 1845 | 1854 |
| 1792 | 1800 | 1809 | 1818 | 1828 | 1837 | 1846 | 1855 |
| 1793 | 1801 | 1810 | 1819 | 1829 | 1838 | 1847 | 1856 |
| 1794 | 1802 | 1811 | 1820 | 1830 | 1839 | 1848 | 1857 |
| 1795 | 1803 | 1812 | 1821 | 1831 | 1840 | 1849 | 1858 |
| 1796 | 1804 | 1813 | 1822 | 1832 | 1841 | 1850 | 1859 |
| 1797 | 1805 | 1814 | 1823 | 1833 | 1842 | 1851 | 1860 |
| 1806 | 1815 | 1824 | 1834 | 1843 | 1852 | 1861 | |
| 1825 |
When the moon is viewed through a good telescope, there appear vast cavities and asperities on various parts of her face, some of them extremely resembling deep caverns and vallies, and others mountains.
“Turn’d to the sun direct, her spotted disk
Shows mountains rise, umbrageous vales descend,
And caverns deep, as optic tube descries.”
The cavities, it is conjectured, do not contain water; hence it is concluded that there can be no extensive seas and oceans, like those which cover a great part of our earth. It is, however, imagined that there may be springs and rivers. The moon seems, as a learned author has observed, in almost every respect to be a body similar to our earth, to have its surface diversified by hill and dale, mountains and vallies, rivers and lakes. With regard to a lunar atmosphere, the existence of which has long been a subject of much dispute, it is now generally admitted.[122] The irregularity of the moon’s surface, arising from hills and vallies, renders her more capable of reflecting the sun’s rays to us. Though philosophers have differed widely in their ideas concerning the materials of the moon’s mountains, some from their brilliancy even supposing them to be rocks of diamonds, there is no diversity of opinion as to their use. If smooth and polished, like a mirror, or covered with water, she would not reflect and distribute the light received from the sun. In some positions she would show us his image no larger than a single point, and with a lustre that would injure our sight: but roughened by these hills and vallies, her surface returns the sun’s light to us in an equable and pleasant manner, and enables us to examine her with ease and precision.
That the moon is a planet similar to our earth, is a sentiment very early adopted. Orpheus is the most ancient author, whose opinion on this subject has come down to us. Proclus presents us with three verses of that philosopher, wherein he positively asserts, that the moon was another earth, having in it mountains, vallies, &c. Pythagoras, who followed Orpheus in many of his opinions, taught likewise, that the moon was an earth like ours, replete with animals, whose nature he presumed not to describe, though he was persuaded they were of a more noble and elegant kind than ours, and not liable to the same infirmities. Stobæus gives us the opinion of Democritus about the nature of the moon, and the cause of those spots which we see upon its disk. That great philosopher imagined, that “those spots were no other than shades, formed by the excessive height of the lunar mountains,” which intercepted the light from the lower parts of that planet, where the valleys formed themselves into what appeared to us as shades or spots. Plutarch went further, alleging, that there were embosomed in the moon, vast seas and profound caverns: he says, those deep and extensive shades which appear upon the disk of that planet, must be occasioned by the vast seas it contains, which are incapable of reflecting so vivid a light, as the more solid and opake parts; “or by caverns extremely wide and deep, wherein the rays of the sun are absorbed,” whence those shades and that obscurity which we call the spots of the moon. And Zenophanes said, that those immense cavities were inhabited by another race of men, who lived there just as we do upon earth.
“And oft I think, fair planet of the night,