M) 



DIVING BELL. 



Pi ATT 



MI. 



Tackle for 



it. 



Hf. 1.5. 



this bell WM a square chert of cart iron, which weigh- 



) cwt. was heavy enough to -ink itself, and 



being *A feet in height, 4j feet in length, and .; f. , t 



-.>ni Millicient for two nun at a time 



to work under it. But it was peculiar to this machine 



that tin- men were fnrni-hed with .1 constant in- 



:' lush air, without ;.ny attention on their 

 thnt necessary article Ix'ing amply supplied by a forcing 

 air-pump in a Ixvtt ii|Hin the irf.u-c. Fig. '_'. 



I'late < ' \\\ 1 1. : a plan, and Fig. .'>. a section of this 

 chest. The bottom JMUI, AH, is made v cry thick, to give 



.ient weight, and in the crown are eight round 

 hola), a n. Fig. '2. each being provided with a lens or 

 glass of four inchc* diameter, fitted into a brass cell, 

 and then screwed into the cast iron. In the centre is a 

 hole h to receive a brass screw at the end of the lea- 

 ther pipe, which introduces the air. This hole, on the 

 underside, has a leather valve stretched over it, to pre- 

 vent the return of the air ; and the hole Iwis a kind of 

 grating of iron across it, to support the valve against 

 the pressure when it is .-hut. The valve is nothing 

 more than a square piece of leather stretched over the 

 hole, and fixed to the iron by a screw at each corner. 

 not so tight but that it can oju-n to admit the air, though 

 it is always kept in its place ; dd are two strong c\c- 

 to receive the chains which suspend the bell, and there 

 are similar eyes within the crown to suspend an iron 

 link M, to which chains may be attached. The whole 

 is cast in one piece : e e are two seats for the clivers to 

 sit upon as they descend, but these turn upon hinges 

 when they descend and go to work. 



The pier, which was afterwards built upon the foun- 

 dation cleared by this machine, was founded by cais- 

 sons; but not being done very substantial! v, or with 

 large stones, the work has in the course of years be- 

 come so bad, as to require renewal in some places, and 

 in others to be defended by an apron or outside wall of 

 very solid masonry, which has been all laid by the div- 

 ing bell. This operation is still going on every summer, 

 and the apparatus employed is shewn in elevation by 

 Fig. 1 . and a plan at Fig. 5. where A A represents die 

 same cant iron bell, attached by two chains to the three- 

 sheaved block a ; another block l>, with three sheaves. 

 :- supported between two long timbers DE. These are 

 united to form one frame, as shewn in Fig. 5 ; and to 

 strengthen them, king posts F, and riders GG, are 

 erected upon them, and very strongly tied by iron 

 straps, and wcxxlen knees. These beams traverse ujxm 

 a centre pin </, which is fixed into a very heavy stone ; 

 ami they are likewise sup|>orted by small wheels which 

 run upon a rail-road II, which is curved to a segment 

 of a circle, as shewn in Fig. 5. The cxtrcmitv I', of 

 frame has a heavy -tone attached to it, to balance 

 the weight of the bell appended from the- opposite 

 end. The fall of the tackle is conducted through a block 

 t, to a capstan, by which it is taken up or let down. 

 This machine is placed ujxdi the- top of the pier wall 

 IK, Fig. 1. at the foot of which the stones dotted at 



re to be laid by the clivers. The different motions 

 are thus given to the bell : to bring it nearer or far- 

 ther from the wall, the block b i- moved in the beam-, 

 and for this purpose it H made to slide freely between 

 tin-in ; to haul it in, a |Kiir of blocks f, /"are u-ed. .-.nil 

 it i- dr.iwn out by a rope passing through a block at I), 

 .-:id thin to the pair of b . rig..",; to move it 



.idewi-e, two pair of tack ; licdat ;', / and /, m ; 



the leather pipe conducted from the- bell to the 



I pump \, which is fixed on board the Ixjat. 

 v the lever lundle ; u- is a 



extendetl from the boll to the boat, and being shorter Dmni; m M. 

 than the pipe, it prevents it from bring broken or *" ' 



i.(l by the wind or tide carrying the boat away; 

 and it is also secured to the pier bv the rojK- />. Tin- 

 man at the pump N is directed to force down so much 

 air to the hell as will cause the air to How out hi-iK-ath 

 the lower edge of the bell, and rise in bubbles to the 

 surface; atkTulangM this continues, he knows that 

 the divers are well supplied with air. As the depth in >i,rnIj. 

 which this machine is used i- very .-mail, the si_ 

 are not made by aline, but by the divers striking with 

 a hammer u|x>n the inside of the cast iron of the bell : 

 This produces a peculiar sound, which can be heard very 

 plainly alx>\ e, and is not liable to be mistaken for any 

 other noise : the nmnlier of blows denotes what they 

 wish, according to the following table, which is paint- 

 ed withinside the bell, and the people above have a du- 

 plicate of it. 



1. More .". To eastward. 



2. Stand f.i-t. (i. To westward. 

 :i. I leave up. 7. From the wall. 

 I. Lower down. 



The manner of proceeding is this: The stones are all Mixicof 

 prepared, and jointed together with do-, i-tails, before working, to 

 they begin to lay them ; and the first thing to IK- done ] uvcl "" 

 is, "to make the foundation perfectly level and true. 

 The loose sand, \c. is removed, by dredging from above st i ncj , 

 in the usual manner ; and then the b;-ll, with two men 

 in it, is let down to the bottom, which, at H;n 

 a hard chalk rock ; when it stands thereon, it lav- the 

 chalk dry to the level of the bottom edge of the bell ; 

 but if the surface is uneven, the bell cannot descend 

 so low but that it will leave (i or 8 inches of water on 

 the bottom. The surface of this water is the level they 

 work to, and by cutting away every eminence which 

 ibove the water, they --cnm obtain a perfect level 

 surface. They work with a small pick, made .something 

 like a narrow ad/.e, for this purpose ; and the work pro- 

 ceeds rapidly, for the chalk is not very hard. When 

 they have accumulated as much rubbish a.s becomes in- 

 convenient, they give three knocks on the bell to or- 

 der the people to draw it up, till they, standing on the 

 bottom, find themselves knee deep ; then two knocks 

 to stand fast. They now take in a shallow basket which 

 has been previously let down from above, and fill the 

 rubbish into it ; then snatch it to order it to be drawn 

 up, and strike four times on the hell that they may be 

 lowered down to proceed with their work. Having in 

 this manner hewed away the surface till the water 

 standing ci|iiallv all over it, shews it to be a perfect 

 level plane, they give orders to be removed to a new 

 situation, yet at -ui-h a small distance that part of the 

 surface they before levelled, is still beneath the 

 in order that Ixith may be brought to one plane. Thus 

 continuing the wc.rk, they get all the rock prepared for 

 the -tone work, without any other lev el than the water. 

 To hoist the stones which are to be l;iid, they use a 

 crane, of which the reader will find a description and 

 figure under our article C'UVNK. It moves on wheels, 

 and can therefore IK- wheeled upon the pier to tl 

 quired spot, close to the diving machine The first stone 

 is taken up by it out of the boat, the hool- of the < 

 rope being p t ,t in the ring of a lewi-. which is an iron 

 wedge, so fitted into a hole in the .-to::e, that it will 

 not draw out by the weight of the stone, though the 

 mason can rclirv e it in a moment. 'I lie stone is turned 

 round into the p<>-ition in which it is to be ' 

 lowered to the bottom as close as is convenient to the 



