422 LECTURE XLIV. 



effect of 1 candle, at the distance of 7 2 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 thou- 

 sand 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 contem- 

 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 

 conjecture and imagination ; and thus, from natural philosophy, our ima- 

 ginations wander into the regions of poetry ; and it must be confessed that 

 the union of poetical embellishment with natural philosophy is seldom very 

 happy. A poet has few facts to communicate, and these he wishes to 

 expand and diversify ; he dwells on a favourite idea, and repeats it in a 

 thousand emblematical forms ; his object is to say a little, very elegantly, 

 in very circuitous, and somewhat obscure terms. But the information, 

 which the natural philosopher has to impart, is too copious to allow of pro- 

 lixity in its detail ; his subjects are too intricate to be compatible with 

 digressions after amusement, which, besides interrupting, are too likely to 

 enervate the mind ; and if he is ever fortunate enough to entertain, it 

 must be by gratifying the love of truth, and satisfying the thirst after 

 knowledge. We have, however, a favourable specimen of highly orna- 

 mented philosophy in Fontenelle's Plurality of Worlds ;* a work which 

 must be allowed to convey much information in a very interesting form, 

 although somewhat tinctured with a certain frivolity which is not always 

 agreeable, We need not attempt to accompany all the flights of Fonte- 

 nelle's imagination ; it will be sufficient for our purpose to pursue his 

 ideas in a simple enumeration of the most remarkable phenomena, that 

 would occur to a spectator placed on each of the planets. 



Of Mercury we know little except the length of his year, which is 

 shorter than three of our months. Supposing all our heat to come from 

 the sun, it is probable that the mean heat on Mercury is above that of 

 boiling quicksilver ; and it is scarcely possible that there should be any 

 point about his poles where water would not boil. The sun's diameter 

 would appear, if viewed from Mercury, more than twice as great as to us 

 on the earth. 



Venus must have a climate far more temperate than Mercury, yet much 

 too torrid for the existence of animals or vegetables, except in some cir- 

 cumpolar parts ; her magnitude and diurnal rotation differ but little from 

 those of the earth, and her year is only one third shorter : so that her sea- 

 sons, and her day and night, must greatly resemble ours. The earth, when 

 in opposition to the sun, must be about four times as bright as Venus ever 

 appears to us, and must, therefore, always cast a shadow ; it must be fre- 

 * 12mo, 1686 ; par Lalande, 1800. 



