22 OBJECTS, ADVANTAGES, AND 



theif own, and placed, to all appearance, immovable, at immense 

 distances from our world, that is, from our solar system. Each of 

 them is probably the sun of some other system like our own, composed 

 of planets and their moons, or satellites ; but so extremely far oif from 

 us, that they all are seen by us like one point of faint light, as you see two 

 lamps, placed a few inches asunder, only like one, when you view them 

 a great way off. The numbers of the fixed stars are prodigious ; even 

 to the naked eye they are very numerous, about 3000 being thus visible; 

 but when the heavens are viewed through the telescope, stars become 

 visible in numbers wholly incalculable : 2000 are discovered in one of 

 the small collections of a few visible stars called Constellations ; nay, 

 what appears to the naked eye only a light cloud, as the Milky Way, 

 when viewed through a telescope, proves to be an assemblage of in- 

 numerable fixed stars, each of them in all likelihood a sun and a sys- 

 tem like the rest, though at an immeasurable distance from ours. 



The size, and motions, and distances of the heavenly bodies are such 

 as to exceed the power of ordinary imagination, from any comparison 

 with the smaller things we see around us. The earth's diameter is 

 nearly 8000 miles in length ; but the sun's is above 880,000 miles, and 

 the bulk of the sun is above 1,300,000 times greater than that of the earth. 

 The planet Jupiter, which looks like a mere speck, from his vast dis- 

 tance, is nearly 1300 times larger than the earth. Our distance from 

 the sun is above 95 millions of miles ; but Jupiter is 490 millions, 

 and Saturn 900 millions of miles distant from the sun. The rate at 

 which the earth moves round the sun is 68,000 miles an hour, or 140 

 times swifter than the motion of a cannon-ball ; and the planet 

 Mercury, the nearest to the sun, moves still quicker, nearly 110,000 

 miles an hour. We, upon the earth's surface, beside being carried 

 round the sun, move round the earth's axis by the rotatory or spinning- 

 motion which it has ; so that every 24 hours we move in this manner 

 near 14,000 miles, beside moving round the sun above 1,600,000 

 miles. These motions and distances, however, prodigious as they are, 

 seem nothing compared to those of the comets, one of which, when 

 furthest from the sun, is 11,200 millions of miles from him; and when 

 nearest the sun, flies at the amazing rate of 8SO,.000 miles an hour. 

 Sir I. Newton calculated its heat at 2000 times that of red-hot iron ; 

 and that it would take thousands of years to cool. But the distance of 

 the fixed stars is yet more vast: they have been supposed to be 

 400,000 times further from us than we are from the sun, that is 38 

 millions of millions of miles : so that a cannon-ball would take 

 between four and five millions of years to reach one of them, supposing 

 there was nothing to hinder it from pursuing its course thither. 



Astronomers have, by means of their excellent glasses, aided by 

 Geometry and calculation, been able to observe not only stars, planets, 

 and their satellites, invisible to the naked eye, but to measure the 

 height of mountains in the moon by observations of the shadows which 

 these eminences cast on her surface ; and they have discovered vol- 

 canoes, or burning mountains, on the same body. 



The tables which they have by the same means been enabled to form 

 of the heavenly motions, are of great use in navigation. By means 

 of the eclipses of Jupiter's satellites, and by the tables of the moon's 



