DIVING BELL. 



Tackle for 

 diving in a 

 river. 

 PLATE 

 CCXXXH. 

 , 8. 



i-.ing BeH. that ninny of the goods weigh very litt'e in the water, 

 <- *~r^ / though when they are taken out they require a pur- 

 chase ; for this reason, the boat should attend as soon 

 as they appear at the surface of the water, and make 

 them fast by another sling, because it cannot lie expect- 

 ed that the divers in their hurry will be able to sling 

 the goods quite so fast to the rope, as may be sufficient 

 to raise them out of the water, though it has brought 

 them from the bottom. 



An apparatus more convenient than the preceding 

 when the bell is to be used in a river or still water, is 

 shewn in Figs. 7. and 8. of Plate CCXXXII. The bell 

 is here suspended between two boats of 1 5 or 20 tons 

 burden each, or they may be such barges as are used on 

 the Thames for transporting coals. These two arc well 

 secured together by cross beams, DD, which preserve 

 them at the same distance, and likewise form the base 

 of a wooden frame DEF, lying across the barges, 

 supporting a beam F, from the middle of which hangs 

 a strong block M for the rope, by which the bell 

 H is suspended ; the other end of the rope goes round 

 a windlass, n, Fig. 7. with a ratchet wheel and click, 

 to raise and lower the bell as occasion requires, b, d, 

 Fig. 8. are smaller blocks, for the ropes to draw up the 

 air barrels; e,fare rollers, turned by winches, which 

 come close together, so that one man can turn them 

 both .it once ; and when one rope de.-ecruN, the other 

 ascends, so as to give a constant supply of air to the 

 divers under the bell H. When the divers wHi to 

 come up, they give a signal to that effect, and the 

 windlass is turned by men until the bottom of the bell 

 is brought above water. A small boat or ratt 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. The 

 signals may lie given by a line, in the same manner as 

 before described ; but as the depth for which such a 

 bell is intended is bnt small, an air-bjrrel may be found 

 sufficient ; and the air-chamber, or small bell above, 

 will not be necessary. In some cases, the air may be 

 more conveniently supplied by an air-pump and leath- 

 er pipe, on Mr Smeaton's plan, which we shall de- 

 scribe. 



Removing ^ n a PP nratus or> this kind would be extremely use- 

 rocks by ful in any large river such as the Thames, where barges 

 gunpowder, are constantly sunk, moorings lost, &c. It would give 

 the rn< i :'.ns of removing sunken rocks, which, though 

 too deep to l>e blasted by the usual methods, may be 

 very dangerous to ships, such as the rock in the Thames 

 at Blackwall, upon which several valuable East India 

 whips have at different periods been wrecked. To pro- 

 ceed in such a business, the divers should descend upon 

 the rock, and with a jumper bore a deep hole in the 

 rock in that place where the powder will be likely to 

 have the be-t effect; in this hole, a tin canister, or 

 glass bottle, containing a proper quantity of gun-pow- 

 der sealed up and well secured from the water, is to be 

 inserted, and the remainder of the hole filled up in the 

 usual way of miners, with pounded ashes, brick-dust, 

 or sand. To fire off this powder under water, is the 

 only remaining difficulty : This may be done, by having 

 a large tin canister communicating with the former, 

 by a very small tube filled with powder, for priming 

 and leading up to the pan of a common gun lock, con- 

 tained within the space of the upper canister, and 

 thus defended from the water : A wire from the trig- 

 ger of the lock is to be conducted through the side of 

 the canister, with proper fittings of leather to make 

 it water tight ; and there must also be a wire handle 



coming through to cock the lock ready 101' discharging : 

 its fitting should be secured in the same manner. Then 

 tying the end of a small line to the trigger-wire, the 

 diver coils sever::! yards of it upon the rock, cocks the 

 lock, and orders the bell to be drawn up, taking the 

 end of the line with him, but being exceedingly cau- 

 tious not to ptdl it till he is above water ; and it is to 

 avoid this that the coil of line is laid on the bottom. 

 When all is ready, he draws up the slack of the line, 

 and fires off the powder by snatching the line. 



We have heard of gun-powder being fired under wa- 

 ter by means of a metal wire leading down to it, and 

 transmitting a strong shock of electricity through the 

 powder to ignite it by the spark. Part of the Aberga- 

 venny wreck was broken up by gunpowder to obtain an 

 entrance into her, before the method of cutting her 

 planks and timbers was employed. 



The diving-bell appears, at first sight, to be capable niv ; ng beB 

 of very extensive use to engineers, in constructing the f or engi- 

 foundation of bridges, piers, sluices, and other works neers. 

 of hydraulic architecture. It would obviate the neces- 

 sity "of coffer-dams to inclose the area of the foun- 

 dation, and of the engines for drawing out the wa- 

 ter, preparations which are generally the occasion of 

 greater labour and expence than the masonry or other 

 work to be performed. Or admitting that the div- 

 ing apparatus in its present state is not capable of be- 

 ing carried to such a degree of perfection as to con- 

 struct the whole of new works, there is no doubt it 

 would be very practicable and satisfactory to a survey- 

 or to have the means of examining the state of his 

 work under water, or making trifling repairs, which, 

 from the great difficulty at present of gaining access to 

 the parts, are neglected and deferred until they become 

 of serious extent. 



Notwithstanding all these apparent advantages, only Mr^Smea- 

 two instances have come to our knowledge of the div- " n ' s , bcU ** 

 ing bell being efficiently employed by engineers ; both ex am> 

 were under the management of the late ingenious Mr 

 Smeaton. His first attempt was to repair the founda- 

 tions of some of the piers of the bridge over tht Tyne, 

 at Hexham, in Northumberland, where the -''o1 ince of 

 the current had excavated the gravel bed of the river, 

 beneath some of the timber floors on which the piers 

 had been built by the caisson method. He succeeded, by 

 the assistance of his diving-bell, in filling up the cavi- 

 ties beneath the foundations with large rough stones, 

 which were not disturbed by the current, although the 

 evil gained upon the remaining parts of the founda- 

 tions too fast to be preserved by any method ; and on 

 the occasion of a violent flood in the year 1782, the 

 whole structure was carried away in the course of a few 

 minutes after it appeared to be in danger. This diving 

 bell was a square chest of wood, three feet six inches, by 

 two feet at the base, and four feet high; and was sup- 

 plied with air by means of a pump. 



In 1 788, Mr Smeaton caused a second diving chest ana at 

 to be made for the purpose of getting up a quantity of Hmntgate. 

 large stones, which some years before had been thrown 

 into the sea at Ramsgate harbour, to secure the founda- 

 tions of the outer pier head. It was in contemplation 

 to build an advanced pier beyond this, and it therefore 

 became necessary to get up these stones ; but as many 

 of them were above a ton in weight, the usual method 

 of tongs was not found applicable ; whereas by this ma- 

 chine one hundred tons were got up in the course of 

 two months. 



Instead of the usual form of a bell or of a conical Made of 

 tube of wood, sunk by weights (externally applied) castirn. 



