ON THE APPEARANCES OF THE CELESTIAL BODIES. 531 



Saturn exhibits a variety of forms according to its angular position: it dis- 

 appears to common observation when either its edge or its dark side is pre- 

 sented to us : but to Dr. Herschel's telescopes it never becomes invisible ; the 

 light reflected from the planet being probably sufficient for illuminating in 

 some measure the side not exposed to the sun's direct rays. 



The comets are seen for a short time, and are again lost to our view ; their 

 tails are in general situated in the planes of their orbits, following them in 

 their descent towards the sun, and preceding them in their ascent, with a 

 slight degree of curvature in their forms; they must also appear to us more 

 or less arched, and of different extent, according to their distances, and to 

 the angular position of the orbits with respect to the ecliptic. 



The proportion of the light afforded by the different heavenly bodies has 

 been variously estimated by various authors; but there is little reason to call 

 in question the accuracy of the experiments and calculations of Mr. Bou- 

 guer. He states the intensity of the moon's light as only one three hundred 

 thousandth of that of the sun. These calculations have been extended by Euler 

 and by Lambert; Euler considers the direct light of the sun as equal to that 

 of 6560 candles of a moderate size, supposed to be placed at the distance of 1 

 foot from the object : that of the moon to the effect of 1 candle, at the distance 

 of 7-i feet; the light of Venus to a candle at 421 feet, and of Jupiter to a 

 candle at 1620 feet; so that the sun would appear as bright only as Jupiter 

 if he were removed to a distance 131 thousand times as great as his present 

 distance. (Plate XXXIV. Fig. 500.) 



"When we reflect on the magnificence of the great picture of the universe, 

 the outlines of which we have been considering, we are lost in the conterri- 

 plation of the immensity of the prospect, and returning to the comparatively 

 diminutive proportions of our individual persons, and of all the objects with 

 which we are most immediately connected, we cannot help feeling our own 

 insignificance in the material world. The mind, notwithstanding, endea- 

 vours to raise itself above the restraints which nature has imposed on the 

 body, and to penetrate the abyss of space in search of congenial existences. 

 But in speculations of this kind, reason and argument must give way to coa- 



