DIVING BELL. 



cavity, which flies out at the upper ori- 

 fice of the cock H. When this is done, 

 the divers turn the handle, which stops 

 the cock, so that if any more air was to 

 get into the cavity AEFB, it could no long- 

 er be discharged through the orifice H 

 as before When this 'cavity is full of 

 water, the bell sinks, but when a consi- 

 derable quantity of air is admitted, it ri- 

 ses. If therefore the divers have a mind 

 to raise themselves, they turn the small 

 cock by which a communication is made 

 between the upper and under cavities of 

 the bell ; the consequence of this is, that 

 a quantity of air immediately enters the 

 upper cavity, forces out a quantity of wa- 

 ter contained in it, and thus renders the 

 bell lighter by the whole weight of the 

 water which is displaced thus. If a cer- 

 tain quantity of air is admitted into the 

 upper cavity, the bell will descend very 

 slowly ; if a greater quantity, it will nei- 

 ther ascend nor descend, but remain sta- 

 tionary ; and if a larger quantity of air be 

 Still admitted, it will rise to the top. It 

 is to be observed, however, that the air 

 which is thus let out into the uppef cavi- 

 ty must be immediately replaced from 

 the air barrel, and the air is to be let out 

 very slowly, or the bell will rise to the 

 top with so great velocity, that the di- 

 vers will be in danger of being shaken 

 out of their seats : but by following 

 these directions, every possible accident 

 may be prevented, and people may de- 

 scend to very great depth without the 

 least apprehension of danger ; the bell al- 

 so 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 

 those who are in it. 



Instead of wooden seats, used by Dr 

 Halley, Mr. Spalding made use of ropes 

 suspended by hooks b, b, b, and on these 

 ropes the divers may sit without any in- 

 convenience ; there are two windows 

 made of thick strong glass for admitting 

 light to the divers ; N represents an air 

 cask with its tackle, and C P the flexible 

 pipe through which the air is admitted 

 to the bell ; in the ascent and descent of 

 this cask, the pipe, is kept down by a 

 small appended weight, as in Dr. Hal- 

 ley's machine ; R is a small cock, by 

 which the hot air is discharged as often 

 as it becomes troublesome. 



Mr. Spalding is of opinion, that one air 

 barrel, capable of containing thirty gal- 

 lons, is sufficient for an ordinary machine. 



In fig. 1 and 2, are shewn representa- 

 tions of a frame for supporting a diving 



bell, and transporting it from place to 

 place upon the water Fig. 1, is a side 

 elevation, and fig. 2, a section of it. The 

 same letters refer to both figures. A B, 

 fig. 2, are sections of two barges, such 

 as are used upon the Thames, at Lon- 

 don : D E F, is a frame laying across the 

 barges, and supporting a beam, G, from 

 which hangs a strong block for the rope 

 by which the bell, H, is suspended ; the 

 other end of the rope goes round a wind- 

 lass, a, with a ratchet wheel and click, to 

 raise and lower the bell as occasion re- 

 quires : b d are smaller blocks, for the 

 ropes to draw up the air barrels ; e/are 

 rollers, turned by winches, fixed on the 

 opposite barge to the windlass a ; the 

 ropes are wound round these rollers in 

 contrary directions, and the winches 

 come close together, so that one man 

 can turn them both at once, and when 

 one rope descends, the other ascends, so 

 as to give a constant supply of air to the 

 divers under the bell, H. When the 

 divers wish to come up, they give a sig- 

 nal to that purpose, and the windlass is 

 turned by men until the bottom of the 

 bell is brought above water ; a small 

 boat or raft is rowed under the bell, to 

 take the divers out : the same method is 

 to be used to get them in, and this will 

 be done without wetting them, or any 

 other inconvenience. Several small bells 

 of very different tones should be fixed 

 to the beam G, and strings fastened to 

 them should go into the bell, for he 

 divers to ring as signals to the work- 

 men in the barges above. The barges 

 should be well secured jtogether by cross 

 beams. 



Several other machines have been con- 

 trived to answer the purposes of the div- 

 ing-bell ; one of which, tig. 4, was invent- 

 ed in 1753, by Rowe, Esq. and pub- 

 lished in the Universal Magazine. 



The engine is a trunk, or hollow ves- 

 sel, of copper or brass, of sufficient 

 strength to resist the pressures of deep 

 waters, and dimensions to contain the 

 body of a man, supposed to enter there- 

 in feet foremost at *, bent at the bearing 

 of his knees at /, for the more convenient 

 going between rocks and great stones ; 

 at k, and on the other side, are holes for 

 his arms to pass through, and a glass for 

 his sight at n. h represents a sleeve 

 made of soft leather, lined with fine 

 cloth, exactly to fit the diver, and fas- 

 tened to the body of the engine at k, 

 where the arms come through ; which is 

 likewise defended by a soft quilting, to 

 prevent the arms from being hurt by 



