DIVING BELL. 



Its use 



And action* 



Diving BelL cock, by which the hot air is discharged as often as it 

 S "~"Y""' becomes troublesome, and a fresh supply is obtained 



from the air casks. 



Spalding's By another very ingenious contrivance, Mr Spalding 

 double bell rendered it possible for the divers to raise the bell, with 

 PLATE all the weights appended to it, even to the surface, or 

 ccxxxn. to stop at any particular depth as they think proper, 

 *'* * and thus they could still be safe even though the rope 

 designed for pulling up the bell was broke. This was 

 accomplished, by affixing a second bell of smaller di- 

 mensions over the large one, as shewn at S, being fix- 

 ed thereto by screws at different places, as well as by 

 the ropes e, e, which suspend the bell. It contains 25 

 gallons. In the top of it is a cock /, which can be 

 opened by the diver, to permit the air to escape from 

 the upper bell. Its handle comes down into the great 

 bell through the top at t. There is also another cock 

 at v in the top, which permits the air to pass out of the 

 great bell, and rise into the small one. There is so 

 much space left brtwiren the two bells, that the water 

 lias free entrance into the upper as well as into the low- 

 er one. When the bell is first let down the cock t in 

 the top of the upper one is opened, and therefore the 

 air escapes from it, and the water enters till it is full. 

 In this state the bell is, as before mentioned, lighter 

 than an equal bulk of water without the balance weight, 

 though with the addition of that it is heavier. Now if 

 the divers wish to raise themselves, they turn the small 

 cock v, by which a communication is made between the 

 bells. The consequence of this is, that aquantity of air im- 

 mediately enters from the lower into the upper bell, and 

 forces out a quantity of the water contained therein. The 

 r.ir, which is thus let out from the lower bell, must be 

 immediately replaced from the air barrel, and thus ren- 

 ders the bell lighter, by the whole weight of the water 

 which is displaced. The air is to be let out very slowly, 

 otherwise the bell will rise to the top with so great ve- 

 locity, that the divers will be in danger of being shaken 

 out of their seats. The quantity let into the upper bell 

 will determine the rate of its ascent. Thus, if a cer- 

 tain quantity of air is admitted into the upper cavity, 

 the bell with the balance will descend very slowly ; if 

 a greater quantity, it will neither ascend nor descend, 

 but remain stationary ; and if a larger quantity of air 

 is still admitted, it will rise to the top. 



Indeed the bell would rise very slowly when the air 

 is admitted, from the lower into the upper cavity, from 

 another cause, independent of taking in any more air 

 from the barrel. 'I lius the air in the great bell is con- 

 densed, by the pressure of a certain column of water. 

 Now when a portion of the contained air is transferred 

 to the upper bell, that quantity is pressed by a column- 

 of water of 5 or 6 feet less altitude tlum it was before, 

 because the upper bell is that height above the other, 

 ijuently it will expand itself, and displace rather a 

 greater quantity of water from the upper bell than its 

 absence from the lower one admits into it. 



By following these directions, every accident may be 

 prevented, and people may descend to great depths 

 without die least apprehension of danger. The bell 

 also becomes so easily manageable in the water, that it 

 may be conducted from one place to another by a small 

 boat with the greatest ease, and with perfect safety to. 

 tho.se who are in it. 



We consider Mr Spalding's form of the diving-bell 

 as the best adapted of any which has been yet made 

 public for descending deep Into the sen. It may be 

 made of one single cask instead of two. In this case, 

 it must have a false bottom, to divide it into two 

 1 



Aihunu- 



Improve- 

 ment by the 

 writer o 

 this article. 



Air vessel 



and pumps. 



cavities, the air being allowed free entrance info the Diving Belt, 

 lower part of the upper one, through a number of au- ^~~Y~*** 

 ger holes bored through the staves, close above the par. 

 tition. The inventor's reason for making them sepa- 

 rate, was, that he might disencumber his bell of the 

 small one when he did not think it necessary to employ 

 it. 



The writer of this article having had occasion to con- 

 sider the best means of diving to a wrecked ship, in a 

 considerable depth of water, conceived a very material 

 improvement upon Mr Spalding's plan, of dividing the 

 bell into two cavities, so that it can at all times be made 

 heavier or lighter, as the divers wish. At the same 

 time, he drew up a plan for such a system of tackle for 

 the management of any kind of bell, either at sea or 

 in a river, as would greatly facilitate its operation ; for 

 the success of diving, with any kind of bell, will great- 

 ly depend upon the convenience of its tackle, that it 

 may be let down or drawn up, and removed in any di- 

 rection on the bottom with the least possible loss of 

 time; for as it is found injurious to (livers to remain 

 a long time in the condensed air when the depth is very 

 great, if much time is expended in getting to the re- 

 quired situation, they will be unable to do any thing 

 before they find it necessary to return to the surface, to 

 relieve themselves from the pressure. This improve- 

 ment of the bell consists in making the upper cham- 

 ber quite tight, and of considerable strength, having 

 no openings to admit water as in Mr Spalding's machine. 

 It is furnished on the under side with two small brassfor- 

 cing pumps fixed in the partition which forms the cham- 

 ber, and provided with proper valves and pistons, as well 

 as levers with handles for the divers to work them by, 

 and force air into the upper chamber from the bell. 

 The valves of these pumps where they pass through 

 the partition, will permit the air from the bell to enter 

 the chamber when the pressure below is the greatest, 

 but always prevent it from returning. There is a cock in 

 the partition, to allow the air to descend at the pleasure 

 of the diver. The action of this chamber is as follows: 

 When the divers have descended to a certain depth and 

 then stop, as Dr Halley describes, to have as much air 

 sent down as will supply the space, which has been di- 

 minished by the compressure of the contained air, they 

 are to work these pumps, to condense as much as they 

 can of the air into the upper chamber, having the quan- 

 tity which is thus taken from the great bell immedi- 

 ately replenished from the air barrel. By repeating 

 this every time they stop, and also when they arrive 

 at the bottom, they obtain a store of fresh air in reserve 

 for two purposes : First, If by any accident the air bar- 

 rel, or any part of its tackle, should fail, and interrupt 

 the supply of air, they can let out a quantity of air from 

 the upper chamber, to serve them till the tackle is re- 

 paired, or till they can be drawn up. It also gives 

 them the means of adjusting the weight of the bell in a 

 more perfect manner than Mr Spalding's. Thus, if the 

 ballast is so adjusted, that when the bell is full of air 

 all but ') inches of the lower part, its weight without 

 the balance weight is rather lighter than water, so as 

 just to rise but no more, the diver may manage to 

 hold it down or descend, by pulling the balance weight 

 rope with a very slight force. Now in this case, if they 

 require to rise without the aid of those above, they open 

 the cock, let out of the chamber as much air as will ex- 

 pel the water from the (i inches of the lower part of the 

 bell, and thus by displacing more water rendering it suf- 

 ficiently buoyant to rise to the surface, and carry tbe- 

 balancc weight up with it it' required. They have, 



Their use. 



