VOL. XXXIX.] PHILOSOPHICAL TRANSACTIONS. 99 



the campana urinatoria, can be of use in any considerable depths; or that the 

 diver, in any other invention whatever, can be a single moment safe. As to 

 the many inconveniences that attend other inventions, he only mentions that of 

 a water armour, in which the man is drowned in an instant, when such a ma- 

 chine receives the least leak ; whereas experience has shown, that when such an 

 accident has happened to the diving bell, as to his knowledge it did once, when 

 the diver was 12 fathom under water, and a pretty large hole happened to be 

 struck in the bell, by a bolt of the wreck he went upon, when the air rushed 

 out of the same with such violence as astonished the beholders by the excessive 

 boiling on the surface of the water, fearing, not without reason, that the man 

 in the bell vvas drowned; but he clapped his hand to the hole or leak, and gave 

 a sign to be hauled up, which was done with all the ease and safety as if no 

 accident had happened to him, the water having only risen about half a foot 

 into the bell by this leak. 



The very same diver that was then in the bell is 63 years of age, and has 

 used the business of diving ever since he was 20, in a common diving bell. 

 He declares that never a worse accident happened to him in his business, except 

 once, when the bell he was in rushed down at once about a fathom or more, by 

 the carelessness of those that worked the bell; at which time the blood came 

 out of his nose and ears, feeling besides an intolerable pressure on his whole 

 body; which shows, that when a man in a diving bell is slowly and gradually 

 let down, he at such a time and by degrees respiring compressed air, which by 

 the lungs is forced into the blood, cannot feel the external pressure, though of 

 highly compressed air, surrounding him, and that of the water reaching some 

 parts of his body; which convenience no other invention can yield or afford, 

 where the diver is to draw his breath from air in its natural state. 



Mr. T. has often with a great deal of pleasure observed, that when he has 

 caused the bell to stop, being lowered down 5 fathom, and the diver taking in 

 the air contained in an air barrel, lowered down a fathom deeper than the bell, 

 without opening the cock for discharging the hot air; the water would, by the 

 access of the air out of the barrel, be almost all expelled out of the bell ; and 

 when the same was again lowered down 5 fathom more, the same operation with 

 another air barrel repeated, and the bell afterwards hauled up, it was no small 

 matter of delight to see, that every fathom the bell came up, it would discharge 

 itself of the superfluous and large quantity of air; which can)e up from the 

 bottom of the bell in very large bubbles, as large as ostrich eggs; which dis- 

 charge of air and phenomenon continued till the equilibrium of the air in the 

 bell, and pressure of the water, were restored, and till the bell came above the 

 surface of the water. 



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