On the Compressibility of Water. 349 



gun. This fact proves, either that the gun expands, or that 

 the water enters the pores of the cast iron ; it is probable 

 both these circumstances contribute to produce this effect. 



This experiment was made in America, in the year 1819, 

 and before I had time to strengthen my apparatus for the 

 purpose of making farther experiments, I was obliged to 

 embark for this country. On my passage, however, I had 

 frequent opportunities of repeating those I had already 

 made, and of making others, by a natural pressure. They 

 were as follows. The piezometer, by the assistance of fifty- 

 four pounds of lead attached to it, was sunk in the ocean 

 to the depth of five hundred fathoms, which is about equal 

 to the pressure of one hundred atmospheres. When drawn 

 in, the gague or ring was found removed eight inches up the 

 rod, indicating, as in the before-mentioned experiment, a 

 compression of one per cent. This experiment was several 

 times repeated, and with the same result. 



The next experiment was that of sinking a strong empty 

 porter bottle to the depth of an hundred and fifty fathoms, 

 having first tightly corked and sealed it, in the following 

 manner. Six coverings of cotton cloth, saturated with a 

 composition of sealing wax and tar, were strongly fastened 

 over the cork, by a cord wound round them, directly under 

 the projection at the neck of the bottle. After the bottle 

 had been suffered to remain at the depth mentioned a few 

 minutes, it was drawn up. No water was found to have 

 been forced into it, neither was there any visible change at 

 the mouth. 



The same bottle was again sunk, and at the increased 

 depth of two hundred and twenty fathoms : when drawn in, 

 it was found to contain about a gill of water ; but not the 

 slightest visible change had taken place in the sealing. 



The same bottle was now sunk, for the third time, to the 

 still greater depth of three hundred fathoms, and when 

 drawn up, only a small part of the neck was found attached 

 to the Hne. Its appearance was truly interesting. The 

 bottle was not broken by external pressure, but evidently 

 by the expansion of the condensed sea-water, which had 

 found its way through the seahng. Upon examination, it 

 was found that the cork had been compressed into half its 

 length, making folds of about one-eighth of an inch ; and 

 that the coverings, consisting of six layers of cloth and 



