COMMON THINGS THE ALMANACK. 



below the horizon, crossing the invisible half of the meridian at o', 

 and returning to E again to rise. 



Thus, if we suppose the sun at o, which is its place at noon, an 

 object in opposition will be at o', and will therefore be invisible. 

 At sunrise, the sun being at E, an object in opposition will be 

 at or near s, and will therefore be setting; and at sunset, an 

 object in opposition will be at or near E, and will therefore be 

 rising. Between sunset and sunrise, the sun passing over s o' B, 

 an object in opposition will pass over EOS and will be at o at 

 midnight, and will be visible in the heavens during the entire 

 night. 



An object in eastern quadrature will be at E when the sun is at 

 o, at o when the sun is at s, at s when the sun is at o', and at 0' 

 when the sun is at E ; so that from sunset to midnight it is visible 

 in the west. 



An object in western quadrature is at o when the sun is at E, 

 at s when the sun is at o, at o' when the sun is at s, and at E 

 when the sun is at o'; so that from midnight to sunrise it is 

 visible in the east. 



83. It has been already shown (Museum, vol. iii. pp. 36, 37), 

 that when the moon is in conjunction, being between the sun and 

 the earth, and its enlightened hemisphere being presented to the 

 sun, its dark side is turned towards the earth, so that even though 

 it were favourably situated, it could not be seen. But from what 

 has been just explained respecting an object in conjunction, it 

 rises and sets with the sun, and therefore could not serve the 

 purpose of illuminating the night even were it visible. The moon 

 moves round the heavens from west to east at the rate of about 

 13 per day, while the sun moves in the same direction at the 

 rate of about 1 per day. Therefore the moon advances eastward, 

 departing from the sun at the rate of about 12 per day. On the 

 8th day, or about a week after conjunction, therefore, the moon 

 will be 90 eastward of the sun ; and, according to what was 

 proved in vol. iii. pp. 36, 37, the moon will then be halved, the 

 convex side of the semi-lune being presented westward towards 

 the sun. Supposing as before, the observer to stand with his face 

 to the south, the east will be on his left and the west on his right. 

 In the case here supposed, therefore, the moon will appear halved 

 as shown in fig. 7, at 90 east or to the left of the sun, and will 

 follow the sun in its diurnal motion. The dark hemisphere of the 

 moon indicated by the dotted semi-circle is turned eastward. 

 The moon, therefore, in this case, moves with the straight edge of 

 the semi-lune foremost. 



This phase is called in the Almanack the ITEST QTJAETEE. 



After conjunction, and before the moon arrives at this phase of 

 46 



