ESSENTIAL AND PECULIAR. 



63 



The nuclei thus arising may sometimes be double or triple, or still more 

 complicated ; and whenever this occurs, the nebulosity will be broken into 

 different nebulae, or smaller nebulous clouds ; and if some of them be much 

 minuter than others, the minuter may at length attend upon the larger, as 

 satellites upon a planet : and Dr. Herschel gives instances of all these pheno- 

 mena actually completed, or in a train of completion, in different parts of the 

 visible heavens. 



Such he submits as his latest opinion of the general construction of the 

 heavens ; believing stars, planets, and comets to have originated, and to be 

 still originating, from such a source ; the nebulous matter contained in a cu- 

 bical space seen under an angle of ten degrees demanding a condensation of 

 two trillion and two hundred and eight thousand billion times before it can 

 be so concentrated as to constitute a globe of the diameter and density of our 

 sun. 



Some of these masses of light are indistinct and barely visible even by Dr. 

 Herschel's forty feet telescope ; and he hence calculates, that if a mass thus 

 traced out contain a cluster of five thousand stars, they must be eleven mil- 

 lions of millions of millions of miles off. M. Huygens entertained an analo- 

 gous idea : and conceived that there are stars so immensely remote, that their 

 light, although travelling at the rate of eleven millions of miles in a minute, 

 and having thus continued to travel from the formation of the earth, or for 

 nearly six thousand years, has not yet reached us. 



But this sublime conception is of much earlier origin ; and it is due to the 

 magnificence of the Epicurean scheme to state that it is to be found com- 

 pletely developed among its principles. Lucretius has beautifully alluded to 

 it in lines of which I must beg your acceptance of the following feeble trans- 

 lation, the only difference being, that lightning or the electric fluid, is here 

 employed instead of light, at least by Havercamp; for Vossius, in the Ley- 

 den edition, gives us light for lightnings reading lumina instead of Julmina. 



The poet is speaking of the immensity of space : — 



The vast whole 

 Wliat fancied scene can hound 1 O'er its broad realm, 

 Inimeasur'd, and immeasurably spread, 

 From age to age resplendent lightnings urge, 

 In vain, their flight perpetual ; distant, still, 

 And ever distant from the verge of things. 

 So vast the space or opening space that swells, 

 Through every part so infinite alike.* 



From this immense range of nebulous light Dr. Herschel derives comets, 

 as well as stars and planets, believing them, indeed, to be the rudiments of 

 the two latter; and he has especially noticed, as originating from this source, 

 the well-remembered comet that so brilliantly, and for so long a period of time, 

 visited our horizon during the close of the year 1811 ; which he conceives 

 will be converted into a stellar or planetary orb as soon as its luminous mat- 

 ter, and especially that of its enormous tail, shall be sufficiently concentrated 

 for this purpose. This tail he calculated, when at its greatest apparent 

 stretch in October of the same year, at something more than a hundred mil- 

 lions of miles long, and nearly fifteen millions broad, though its bright or 

 solid nucleus or planetary body was not supposed to measure more than four 

 hundred and twenty-eight miles. Its perihelion path, or nearest approach to the 

 sun, is stated at a distance of ninety-seven millions of miles, its distance from 

 the earth at ninety-three millions. The comet of 1807 approached the earth 

 within sixty-one millions of miles, or about a third nearer the earth, and that 



* Omne quidem vero nihil est quod finiat extra. 

 Est igitur natura loci, spatiumque profundi. 

 Quod neque clara t-uo percurrere fulmina cursu 

 Perpetuo possirit labentia tractu; 

 Nec jtrorsum facere, ut restet minus ire, meando 

 Usque adeo jiassim patet ingens copia rebus, 

 Finibus exemptis, in cunctas undique parteis 



t De Rer. Nat. i. 1000. 



