SECTION XVIII. 265 be upon the meridian that day at midnight. And by the same means if you observe what stars are upon the meridian at mid- night, you easily infer the sun is in the opposite point of the hea- vens at miduoon. Here it should not be forgotten, that there is a broad uneven path encompassing the heavens, passing near the north-pole, which is brighter than the rest of the sky, and may be best seen in the darkest night: This is called the Milky Way, which later philosophers have found by their telescopes to be formed by the mingled rays of innumerable small stars. It is to the same cattle that some other bright spots in the sky (though not all) are ascribed which appear to us like whitish clouds in midnight darkness. SECT. XVIII.-Of the Planets and Comets. THOUGH the planets and comets are never painted upon the globe because they have no certain place, yet it is necessary here to make some mention of them ; since they are stars much nearer to us than the fixed stars are, and we know muchmore of them, The planets are in themselves huge dark bodies which receive their light from the sun, and reflect it back to us. They are called planets from a Greek word which signifies wan- derers, because they are always changing their places in the hea- vens, bothwith regard to the fixed stars and with regard to one another. - Theplanets are placed at very different distances from the centre of our world, (whether that be the earth or the sun) and they make their various revolutions through the twelve signs of the Zodiac in different periods of time. Saturn in 29 years and 167 days, i. e. about 24 Weeks. Jupiter in 11 314 45 Mars in 1 321 46 Earth or sun in .1 0 -0 Venus in 0 224 32 Mercury in 0 87 I2i Moon in 0 27' 4 As the ecliptic line is the orbit or annual path of the earth or sun, so each planet has its proper orbit, whose plane differs some fewdegrees from the plane of the orbit of the sun, and to a spectator's eye placed in the centre would intersect or cut the sun's orbit- at two opposite points or nodes. Now the dis- tance of a planet from the ecliptic, measured by an arch perpen- dicular to the ecliptic, is the latitude of that planet as before. To represent thisas in figure xi. you may imagine as many hoops as there are planets thrust through with several strait wires, and thereby joined in different places to the hoop that re-
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