DIVING BELL. 



American Society, Vol. IV. The exter- 

 nal shape of his vessel bore some resem- 

 blance to two upper tortoise shells of 

 equal size, joined together} the place of 

 entrance into the vessel being represent- 

 ed by the opening made by the swell of 

 the shells at the head of the animal. 

 The inside was capable of containing 

 the operator, and air sufficient to sup- 

 port him thirty minutes without receiv- 

 ing fresh air. At the bottom, opposite 

 the entrance, was fixed a quantity of lead 

 for ballast. At one edge, which was di- 

 rectly before the operator, who sat up- 

 right, was an oar for rowing forwards 

 and backwards. At the other edge was 

 a rudder for steering. An aperture at 

 the bottom, with its valve, was designed 

 to admit water for the purpose of de- 

 scending ; and two brass forcing-pumps 

 served to eject the water within when ne- 

 cessary for ascending. At the top there 

 was likewise an oar for ascending or de- 

 scending, or continuing at any particular 

 depth ; a water-gauge or barometer de- 

 termined the depth of descent, a com- 

 pass directed the course, and a ventila- 

 tor within supplied the vessel with fresh 

 air when on the surface. 



The entrance into the vessel was ellip- 

 tical, and so small as barely to admit a per- 

 son. This entrance was surrounded with 

 a broad elliptical iron band, the lower 

 end of which was let into the wood, of 

 which the body of the vessel was made, 

 in such a manner as to give its utmost 

 support to the body of the vessel against 

 the pressure of the water. Above the. 

 upper edge of this iron band there was a 

 brass crown or cover, resembling a hat 

 with its crown and brim, which shut 

 water tight upon this iron band. The 

 crown was hung to the iron band with 

 lunges, so as to turn over sideways when 

 open. To make it perfectly secure when 

 shut, it might be screwed down upon the 

 band by the operator, or by a person with- 

 out. 



There were in the brass crown three 

 round doors, one directly in front, and 

 one on each side, large enough to put the 

 hand through : when open they admitted 

 fresh air ; their shutters were ground per- 

 fectly tight into their places with emery, 

 hung with hinges, and secured in their 

 places when shut ; there were likewise 

 several small glass windows in the crown, 

 for looking through and admitting light 

 in the day time, with covers to secure 

 them. There were two air-pipes in the 

 crown. A ventilator within drew fresh 

 air through one of the air pipes, and dis- 



charged it into the lower part of the ves- 

 sel ; the fresh air, introduced by the ven- 

 tilator, expelled the impure light aiv 

 through the other air pipe. Both air 

 pipes were so constructed, that they shut 

 themselves whenever the water rose near 

 their tops, so that no water could enter 

 through them, and opened themselves 

 immediately after they rose above the 

 water. 



The vessel was chiefly ballasted with 

 lead fixed at the bottom ; when this was 

 not sufficient, a quantity was placed with- 

 in, more or less, according to the weight 

 of the operator ; its ballast made it so 

 stiff, that there was no danger of its over- 

 setting. The vessel, with all its appen- 

 dages, and the operator, was not of suffi- 

 cient weight to settle it very low in the 

 water. About two hundred pounds of 

 the lead at the bottom for ballast could 

 be let down forty or fifty feet below the 

 vessel ; this enabled the operator to rise 

 instantly to the top of the water in case 

 of accident. 



When the operator would descend, he 

 places his foot on the top of a brass valve, 

 pressing it, by which he opened a large 

 aperture at the bottom of the vessel ; 

 through this the water entered at his 

 pleasure ; when he had admitted a suffi- 

 cient quantity, he descended very gra- 

 dually; if he admitted too much, he 

 ejected as much as was necessary to ob- 

 tain an equilibrium by the two brass forc- 

 ing pumps which were placed at each 

 hand. Whenever the vessel leaked, or 

 he would ascend to the surface, he also 

 made use of these forcing pumps. When 

 the skilful operator had obtained an equi- 

 librium, he could row upward or down- 

 ward, or continue at any particular depth, 

 with an oar placed near the top of the 

 vessel, formed upon the principle of the 

 screw, the axis of the oar entering the 

 vessel ; by turning the oar one way, he 

 raised the vessel ; by turning it the other 

 way he depressed it. 



A glass tube, eighteen inches long and 

 one inch in diameter, standing upright, 

 its upper end closed, and its lower end, 

 which was open, screwed into a brass 

 pipe, through which the external water 

 had a passage into the glass tube, served 

 as a water-gauge or barometer. There 

 was a piece of cork, with phosphorus on 

 it, put into the water-gauge. When the 

 vessel descended, the water rose in the 

 water-gauge, condensing the air within, 

 and bearing the cork with its phosphorus 

 on its surface. By the light of the phos- 

 phorus, the ascent of the water in the 



