THE DIVING BELL. 81 



king, and became the founder of the noble house of Mulgrave, which has played no 

 inconsiderable part in the affairs of the United Kingdom. 



It is little more than a century and a half ago since the celebrated astronomer, Hal ley 

 about the first to commence those experiments in submarine exploration which have been 

 continued to the present epoch descended to a depth of fifty feet in a diving-bell which 

 he had constructed. It was built of wood, and covered with sheet lead. The air that 

 was vitiated by respiration escaped from the chamber through an air-cock, while the 

 pure element was supplied by barrels, which descended and ascended alternately on both 

 sides of the bell, like buckets in a well. These barrels, lined with metal, each contained 

 some thirty-six gallons of condensed air ; they were connected with the interior of the bell 

 by leathern tubes. As soon as one of these air receptacles was exhausted another was 

 let down. Halley himself relates that in 1721, by the aid of this apparatus, he was 

 able to descend with four other persons to a depth of nine or ten fathoms, and to remain 

 under water an hour and a half. 



It is to Smeaton, the celebrated engineer of the famed Eddystone Lighthouse, that the 

 diving-bell owes its leading characteristics, as he was the first to abolish Halley's rather 

 clumsy contrivance and apply the power of the air-pump ; he also constructed the first 

 cast-iron bell. In 1779 he made use of the diving-bell to repair the piles of Hexham 

 Bridge, in the north of England, the foundations of the structure having been undermined 

 by the violence of the current. A few years after a sad accident occurred from the 

 use of Halley's barrel apparatus. 



In 1783, Mr. Spalding, of Edinburgh, who had made some improvements upon the 

 mechanical arrangements of Halley 's bell, but had retained the barrel air service, engaged 

 to recover some of the cargo of an East-Indiaman which had been sunk on the Kish 

 Bank, Ireland. He and his assistant went down, and after the first supply of air was 

 exhausted the barrels were sent down as usual. No signal having been given for some 

 time, the bell was drawn up, and Mr. Spalding and his assistant were found to be dead. 

 It is supposed that by some means they failed to discharge the air from the barrels into 

 the bell, and were consequently suffocated. The barrel service was always more or less 

 dangerous, from its liability to get out of gear, and if Spalding had adopted the invention 

 of Smeaton, he would not have lost his life in the manner he did. 



The improved diving-bell was soon generally adopted by engineers, and played an 

 important part in the works which have so altered the port of Ramsgate. The great 

 engineer Rennie made constant use of the diving-bell in fixing the foundations of the 

 eastern jetty, and in protecting it in parts against the attacks of the sea by a shield of solid 

 masonry. It was extensively used in the construction of the Plymouth Breakwater. M. 

 Esquiros, who visited the divers during the progress of that great work, gave an interesting 

 account of their modus operandi : 



" But we now," says he, " approached the breakwater that causeway of giants by 

 the side of which we soon discovered an old dismasted ship. This vessel is rough in 

 appearance, and covered over with a kind of pent-house roof. In it live, as in a floating 

 house, the operatives who are still working at the breakwater. They pass, alternately, one 

 month on board ship and one month on shore. One of their little sources of profit consists 

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