ON THE NON-PERMEABILITY OF GLASS BY WATER. 73 



placed in tlie bottle to support a cork^ over which was inserted saw- 

 dust and melted pitch ; a wooden plug, dipped in hot pitch, was 

 driven in, and through the top of the plug a nail was passed trans- 

 versely, secured with twine ; the whole was then coated over with 

 melted pitch. Mr. Benson, the surgeon of the ship. Princess Viclo- 

 ria, also prepared a bottle as follows : — a cork was tightly driven in 

 and covered over with bladder and leather, after which it was pitched 

 and a wooden cap placed closely over the mouth and neck, secured 

 with a piece of canvas. The three bottles were then sunk to the 

 depth of 58 fathoms; when hauled up, the bottle. No. 1, contained 

 about an ounce of water; the other two bottles were perfectly free 

 from any liquid. The bottles were again lowered in 83 fathoms 

 without any addition to the water, and a third time in 112 fathoms; 

 when, on being carefully examined. No. 1 was found one-fourth full, 

 and the water discoloured with the wine; the second bottle contained 

 about an ounce of water : Mr. Benson's was, also, two-thirds full, 

 with the cork driven in and floating on the surface, and the water 

 much agitated, having the appearance of champagne when the cork 

 is first drawn, the air producing a loud hissing in its effort to escape. 

 In making this experiment the lines were impelled towards the west, 

 by a strong current setting in from the east, which rendered it ne- 

 cessary to back the boat to the west, with considerable rapidity, in 

 order to sink the lines perpendicularly. On the bottles being low- 

 ered a fourth time to the same depth, viz., 112 fathoms, Mr. Ben- 

 son's bottle, when brought up, was quite full of water, and the cork 

 replaced in its original position ; the-M^ater in bottle No. 2 was not 

 increased, but the nail, passed through the plug, was very considera- 

 bly bent inward, and the top of the cork and pitch brought nearly 

 on a level with the glass. The bottle No. 1 had received an addi- 

 tional quantity of water, making it one-third full, but there was no 

 perceptible change in the outer coverings. 



Another experiment was subsequently made by sinking a bottle, 

 prepared as described in figure 4, in the subjoined diagram, to the 

 depth of 142 fathoms, sustaining a pressure of about 426 pounds on 

 the inch. When drawn up, it was found that no water had pene- 

 trated the bottle, and the only perceptible alteration was an inden- 

 tation of about one-fourth of an inch in the lead, produced by the 

 excessive pressure. 



