Dr. Green's Experiments on the Pressure of the Sea. 37 



bottle is drawn up from a depth of 200 or 300 fathoms, it is 

 found filled or nearly filled with water, the cork sound, and 

 in its first situation, and the wax and tar unbroken. Two 

 experiments are mentioned, in which vessels with air-tight 

 glass stoppers were used. In one case the bottle was broken, 

 and in the other some drops of water were found in it. 



How does the water find its way into the bottles ? There 

 are two opinions : One is, that it passes through the cork and 

 all its coverings, in consequence of the vast pressure of super- 

 incumbent water, in the same manner as blocks of wood are 

 penetrated by mercury in the pneumatic experiment of the 

 mercurial shower. The other and less popular opinion is, 

 that the water is forced through the pores of the glass*. 



The following experiment, which I made on the 7th of 

 May 1828, in latitude 48+ longitude 24° 34', will perhaps 

 throw some light on this subject. — Mr. Charles Dixey, the 

 obliging and intelligent master of the packet-ship Algonquin , 

 had a boat rowed off from the ship for me, to the distance of 

 about half a mile, when the sea was almost perfectly calm. 

 A hollow glass globe hermetically sealed, which I had pre- 

 viously prepared in Philadelphia, was then fastened to a line, 

 and sunk, with a heavy mass of lead, to the depth of 230 fa- 

 thoms, or 1380 feet. On the same line, and 30 fathoms above 

 the glass globe, was fastened a small bottle with an air-tight glass 

 stopper ; 50 fathoms above this, a stout glass bottle with a long 

 neck was tied ; a good cork was previously driven into the 

 mouth of this bottle, which was then sealed over with pitch, 

 and a piece of linen dipped in melted pitch was placed over 

 this ; and when cool, another piece of linen treated in the 

 same way was fastened over the first. Twenty fathoms above 

 this bottle, another was attached to the line, much stouter, 

 and corked and sealed like the first, except that it had but 

 one covering of pitched sail-cloth. Thirty fathoms above this 

 was a small thin bottle filled with fresh water closely corked ; 

 and 20 fathoms from this last there was a thin empty bottle 

 corked tight and sealed, a. sail-needle being passed through- 

 and-through the cork, so as to project on either side of the 

 neck. 



Upon drawing in the line, thus furnished with its vessels, 

 and which appeared to have sunk in a perpendicular direction, 

 the following was the result: 



The empty bottle with the sail-needle through the cork, 



* See Perkins on Pressure, Phil. Mag. vol. lvii. p. 54. J. Deuchar's Re- 

 marks on the same, Ibid. vol. Iviii. p. 201. Campbell's Travels, 1st series, 

 p. 3.35. Sillhnan's Journal, vol. xiv. p. 194. Deuchar's Mem. in the Trans, 

 of the Wernerian Soc. 1821 —-2—3. 



and 



