320 Mr Dunlop's Eocperiments xvith Bottles sunk in the Sea, 



In preparing for the second set of experiments, I attempt- 

 ed to guard against the possibility of the corks being forced 

 in, or the pressure of the circumincumbent column at all affect- 

 ing the corks. I prepared two (four or five ounce) phials : the 

 corks were dipped in strong gum dissolved in ether, and thrust 

 into the mouth of the phials ; they were allowed to remain in 

 this state for several days to dry. The corks were then cut 

 close to the mouth, and covered with several thick coats of var- 

 nish, and afterwards covered with leather firmly tied round 

 the neck, which was also covered or soaked in varnish, and suf- 

 fered to dry ; and for farther security, the heads and necks of 

 the phials were immersed in brass caps, filled with melted seal- 

 ing-wax, to prevent the possibility of pressure upon the corks. 

 I also prepared a small phial by simply thrusting in the cork 

 as tight as possible, and cutting it close to the mouth, and af- 

 terwards covering the mouth and neck of the phial one-fourth 

 of an inch thick with black sealing-wax. On the 15th May, in 

 Lat. 5° North, and Long. ^Q" West (the ship becalmed), these 

 three phials were wrapped in old canvas, and, together with 

 the thermometers and glass globes used in the former experi- 

 ments, were all put into a tin case, open at the top, and fasten- 

 ed to the line just above the lead : a porter bottle, fitted up as 

 formerly, was also attached to the line. The boat was rowed a 

 short distance from the ship, and the lead let down 180 fathoms, 

 and allowed to remain about eight or ten minutes at that depth 

 before we commenced hauling in the line. On examining the ex- 

 periments, the two (five ounce) phials, which were secured by the 

 brass caps, were broken or crushed to powder, with the excep- 

 tion of the thick part of the bottom, and the neck which was 

 protected by the brass caps. The other small phial, which 

 was much stronger in the glass, and only secured by the cork, 

 covered one-fourth of an inch thick with sealing-wax, was not 

 broken or injured in the least, though a very minute quantity 

 of water had found its way into the phial, probably through the 

 wax and cork, and, I have no doubt, had the phial been allowed 

 to remain sufficient time at that depth, that it would have filled 

 with water, probably without breaking the wax, or forcing in 

 the cork. Neither the thermometers nor the small glass globes 

 were broken, nor could I perceive the slightest appearance of 



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