136 Dr Hunt, Celestial Chemistry [Nov. 28, 



weight of such an atmosphere "may hinder the globe of the sun 

 from being diminished except by the emission of light ;" while in 

 the second English edition, in 1718, we find a farther addition in 

 the words, "and a very small quantity of vapours and exhalations." 

 A similar change of view appears in the Query now numbered 28, 

 we read of "places [almost] destitute of matter," and also that "the 

 sun and planets gravitate towards each other without [dense] 

 matter between." In these quotations, the two words in brackets 

 are wanting in the edition of 1704, and first appear in that of 

 1718; while the language which we have in a previous page 

 quoted from this same Query was added in the edition of 1706. 



The Queries now numbered 17 — 24, appeared for the first time 

 in the edition of 1718, and herein we find, in 18, the etherial 

 medium spoken of as being "by its elastic force expanded through 

 all the heavens." Of this medium "which fills all space ade- 

 quately" he asks, "may not its resistance be so small as to be 

 inconsiderable," and scarcely to make any sensible alteration in the 

 movements of the planets 1 ? This complex ether of the interstel- 

 lary space was thus in the opinion of Newton made up in part of 

 matter common to the planetary and stellar atmospheres, the origin 

 and importance of which is concisely stated in the paragraph which 

 appears for the first time in 1713, in the second edition of the 

 Principia, in the third book, at the end of proposition 42, here 

 much augmented. In this statement, which serves to supplement 

 and complete that already made in 1687, in proposition 41, we 

 read, that the vapours which arise alike from the sun, the fixed 

 stars and the tails of comets, may by gravity fall into the atmo- 

 spheres of the planets, and there be condensed, and pass into the 

 forms of salts, sulphurs, {id est, combustible matters,) tinctures, 

 clay, sand, coral, and other terrestrial substances'' 2 . 



The conception of Newton who, while rejecting alike the 

 plenum of the Cartesians with its vortices, and an absolute 

 vacuum, imagined space to be filled with an exceedingly attenuated 

 matter, through which a free circulation of gaseous substances might 

 take place between distant worlds, has found favour among modern 

 thinkers, who seem to have been ignorant of his views. Sir 

 William Grove in 1842 suggested that the medium of light and 

 heat may be "a universally diffused matter," and subsequently, in 

 1843, in the chapter on Light, in his Essay on the Correlation of 



1 Compare this with Prop. x. Book III. of the Principia. 



2 " Vapores autem, qui ex Sole et stellis fixis et caudis cometarum oriuntur, inci- 

 dere possunt per gravitatem suam in atmosphaeras planctarum, et ibi condensari 

 et converti in aquam et spiritos humidos, et subinde per lentem calorem in sales, et 

 sulphura, et tincturas, et linium, et lutum, et argillam, et arenam, et lapides, et co- 

 ralla, et substantias alias terrestres paulatirn migrare." — Newton, Principia, lib. III. 

 prop. xlii. 



