touching his Theory of Light and Colours. 191 



and resting there awhile, then leaping clown and resting there, 

 then leaping up, and perhaps down and up again, and this 

 sometimes in lines seeming perpendicular to the table, some- 

 times in oblique ones; sometimes also they would leap up in 

 one arch and down in another divers times together, without 

 sensible resting between, sometimes skip in a bow from one 

 part of the glass to another without touching the table, and 

 sometimes hang by a corner and turn often about very nimbly, 

 as if they had been carried about in the midst of a whirlwind, 

 and be otherwise variously moved, every paper with a divers 

 motion. And upon sliding my finger on the upper side of the 

 glass, though neither the glass nor the enclosed air below were 

 moved thereby, yet would the papers as they hung under the 

 glass receive some new motion, inclining this way or that way, 

 accordingly as I moved my finger. Now whence all these 

 irregular motions should spring I cannot imagine, unless from 

 some kind of subtile matter lying condensed in the glass, and 

 rarefied by rubbing, as water is rarefied into vapour by heat, 

 and in that rarefaction diffused through the space round the 

 glass to a great distance, and made to move and circulate va- 

 riously, and accordingly to actuate the papers, till it returns 

 into the glass again and be recondensed there. And as this 

 condensed matter by rarefaction into an aetherial wind (for 

 by its easy penetrating and circulating through glass I esteem 

 it aetherial) may cause these odd motions, and by condensing 

 again may cause electrical attraction with its returning to the 

 glass to succeed in the place of what is there continually re- 

 condensed ; so may the gravitating attraction of the earth be 

 caused by the continual condensation of some other such like 

 aetherial spirit, not of the main body of phlegmatic a?ther, but 

 of something very thinly and subtilely diffused through it, 

 perhaps of an unctuous, or gummy tenacious and springy na- 

 ture; and bearing much the same relation to aether which the 

 vital aerial spirit requisite for the conservation of flame and 

 vital motions does to air. For if such an aetherial spirit may 

 be condensed in fermenting or burning bodies, or otherwise 

 coagulated in the pores of the earth and water into some 

 kind of humid active matter for the continual uses of nature 

 (adhering to the sides of those pores after the manner that 

 vapours condense on the sides of a vessel), the vast body of 

 the earth, which may be everywhere to the very centre in 

 perpetual working, may continually condense so much of this 

 spirit as to cause it from above to descend with great celerity 

 for a supply : in which descent it may bear down with it the 

 bodies it pervades with force proportional to the superficies 

 of all their parts it acts upon, nature making a circulation by 



