]0C) HISTORY OF 



confused and uncertain accounts of the places below. In tie 

 great diving-bell improved by Dr Halley, which was large 

 enough to contain five men, and was supplied with fresh air 

 by buckets, that alternately rose and fell, they descended fifty 

 fathom. In this huge machine, which was let down from the 

 mast of the ship, the doctor himself went down to the bottom, 

 where, when the sea was clear, and especially when the sun 

 shone, he could see perfectly well to write or read, and much 

 more to take up any thing that was underneath : at other times, 

 when the water was troubled and thick, it was dark as night be- 

 low, so that he was obliged to keep a candle lighted at the bot- 

 tom. But there is one thing very remarkable, that the water 

 Mhich from nHove was usually seen of a green colour, when 

 looked at from below, appeared to him of a very different one, 

 casting a redness upon one of his hands, like that of damask 

 roses:' — a proof of the sea's taking its colour not from any 

 thing floating in it, but from the different reflections of the rays 

 of light. Upon the whole, the accounts we have received from 

 the bottom, by this contrivance, are but few. We learn from it, 

 and from divers in general, that while the surface of the sea may 

 be deformed by tempests, it is usuiJly calm and temperate be. 

 low ;■ that some divers, who have gone down when the weather 

 was calm, and came up when it was tempestuous, were sur- 

 prised at their not perceiving the change at the bottom. This, 

 however, must not be supposed to obtain with regard to the tides, 

 and the currents, as they are seen constantly shifting their bot- 

 tom ; taking their bed with great violence from one place, and 

 depositing it upon another. We are informed, also, by divers, 

 that the sea grows colder in proportion as they descend to the 

 bottom ; that as far as the sun's rays pierce, it is influenced by 

 their warmth ; but lower, the cold becomes almost intolerable. 

 A person of quality, who had been himself a diver, as Mr Boyle 

 informs us, declared, that though he seldom descended above 

 three or four fathoms, yet he found it so much colder than near 

 the top, that he could not well endure it ; and that being let 

 down in a great diving-bell, although the water could not im- 

 mediately touch him, he found the air extremely cold upon his 

 ''^rst arrival at the bottom. 



I Newton's Optics, p. W. 2 Hoylo, vol. iii. p 242. 



