D I V 
altitude within the hell. This fituation is much better 
than when the whole body is raifed above the water in 
the bell, becaufe near the furface of the water the air is 
much cooler and fitter to breathe in than at the top of 
the machine. That the diver alfo might remain conve¬ 
niently in the upper part of the bell, Triewald arranged 
his apparatus fo that when the diver had breathed as 
long as poffible in the upper air, he fixed at the fide of 
the bell a fpiral pipe, through which he could draw in 
the lower cool-air which was over the furface of the wa¬ 
ter. To the upper end of this copper pipe is affixed a 
pliable leather one, with an ivory mouth-piece, which 
the diver puts into his mouth, and thus infpires frefli air, 
in whatever polition-his body might be. A delineation of 
this diving-machine is alfo given at fig. 2, of the annexed 
engraving. 
A farther improvement on the diving-bell has been 
offered by Mr. Spalding of Edinburgh. A fedtion of 
liis diving-bell is reprefented at fig. 3, in the fame en¬ 
graving; the condrufc'tion of which will be ealily under- 
ffood from the following defcription. The bell is made 
of wood, having two fets of drong iron rings, by means 
of which it is fufpended by ropes, as exprelfed in tbe fi¬ 
gure : at the lower extremity of the ropes, on each fide, 
are iron hooks, to which are appended leaden weights, 
that keep the. mouth of the bell always parallel to the 
furface of the water. By thefe weights alone, however, 
the bell would not fink : another is therefore added in 
the center, which can be raifed or lowered at pleafure, 
by means of a rope paffing over a pulley, towards the 
top of the bell. As the bell defcends, this weight, called 
the balance weight, hangs down below the mouth of the 
bell. In cafe the edge of the bell is caught by any rock or 
other obdacle, the balance-weight is immediately lowered 
down, fo that it may reft upon the bottom. By this 
means the bell is lightened, fo that all danger of overfet- 
ting is removed ; for, being lighter, without the balance- 
weight, than an equal bulk of water, it is evident that the 
bell will rife as far as the length of the rope affixed to the 
balance-weight will allow it. This weight, therefore, 
ferves as a kind of anchor to keep the bell at any particu¬ 
lar depth which the divers may think neceffary ; or by 
pulling it quite up, the defcent may be continued to the 
very bottom. By another' ingenious contrivance, Mr. 
Spalding rendered it poffible for the divers to raife the 
bell, with all the weights appended to it, quite to the 
furface of the water, or to ftop at any given depth ; and 
thus they could (fill be fafe, even though the rope 
defigned for pulling up the bell (hould break. For this 
purpofe the bell is divided into two cavities, both of 
which are made as tight as poffible. Juft above the fe- 
cond bottom A, are fmall flits in the fides of the bell ; 
through which the water, entering as the bell defcends, 
difplaces the air originally contained in this cavity, which 
flies out at the upper orifice of the cock B. When this 
is done, the divers turn the handle C, which flops the 
cock ; fo that if any more air was to get into the upper 
cavity, it could no longer be difcharged through the 
orifice B, "as before. When this cavity is full of water, 
the bell finks; but, when a confiderable quantity of air 
is admitted, it rifes. If therefore the divers have a mind 
to raife themfelves, they turn the cock C, by which a 
communication is made between the upper and under ca¬ 
vities of the bell. The confequence is, that a quantity 
of air immediately enters the upper cavity, forces out 
the water contained in it, and thus renders the bell lighter 
by the whole weight of the water which is difplaced.' 
I-Ience, if a certain quantity of air is admitted into the 
upper cavity, the bell will defcend very (lowly ; if a 
greater quantity, it will neither afccnd nor defcend, but 
remain flationary ; and if a larger quantity of-air is ftill 
admitted, it will rife to the top. It is to be obferved, 
however, that the air which is thus let into the upper 
cavity muft be immediately replaced from the air-barrel; 
and the air is to be let out very flowly, or the bell will 
Vol. V. No. 325, 
I N G. 913 
rife to the top with great velocity. This bell is fo eafily 
manageable in the water, that it may be conducted from 
one place to another by a fmall boat with the greatef! eafe, 
and with perfedt fafety. It is furnifhed with two win¬ 
dows made of thick plate glafs, for admitting light to the 
divers; and at its fide is let down an air-cafk, with a flex¬ 
ible pipe, through which the air is admitted to the bell. 
In the afcent and defcent of this cafk, the pipe is kept 
down by a fmall weight appended, as in Dr. Halley’s ma¬ 
chine. 
In Martin’s Philofophia Britannica, we are told of a 
gentleman of Devonfhire, who invented a large cafe of 
ftrong leather, perfedtly water-proof, which contained 
about half a hogfliead of air. This was fo contrived, 
that, when he (hut himfelf up in this cafe, he could walk 
at the bottom of the fea, and go into any part of a 
wrecked veflel, and deliver out the goods. This method, 
we are told, he pradtifed for many years, and acquired a 
large fortune. 
Upon a fomewhat fimilarplan, C. H. Klingert, of Bref- 
lau, feems to have invented a harnefs or fuit of armour, 
by which a man may explore the bottoms of deep rivers, 
or defcend into the ocean, with as much fafety as under 
the diving-bell. The principle of his apparatus is as fol¬ 
lows : It is well known, that the preflure of water in- 
creafes with its depth ; and as water is a denfe body, a 
man cannot defcend far in it without experiencing a very 
ftrong preflure : fo that if a diver, whofe head is five feet 
below the furface, attempts to breathe through a pipe, 
he finds himfelf incapable of inhaling the air, on account 
of the preflure he fuftains on his bread:. A man, there¬ 
fore, to defcend to a great depth, mud have his body'and 
bread free from the external preflure of the fluid. In 
order to fecure him from this inconvenience, the armour 
is made of drong tin plate, in the form of a cylinder, 
which goes over the diver’s head, and which confids of 
two parts, that he may more conveniently put it on ; alfo 
a jacket with fhort fleeves, and drawers of drong leather. 
All thefe being water-tight, and clofely joined round the 
body of the diver, fecure every part of him but the arms 
and legs from the preflure of the water, which at the 
depth of twenty feet will occafion no 1 inconvenience to 
thefe parts. Fig. 4, in the engraving, reprefents the di¬ 
ver covered with the armour, jacket, and drawers. In 
the infide of the cylinder is a drong broad iron hoop, to 
enable it to withdand the preflure of the water; and in 
the infide of the top or helmet, there are two pieces of a 
drong hoop of the fame kind, placed over qach other in 
the form of a crofs. A drong ring of brafs wire is fol- 
dered upon the outfide, that the jacket may be fadened 
to it with an elafiic bandage, to prevent it from flipping 
downwards. In the front of the helmet are lioies to 
afford light, into which eye-glaffe,s are fcrewed ; and there 
is another opening into which the mouth-piece of the 
breathing pipe is fcrewed, with an aperture at the fide, 
for the purpofe of breathing when out of the water, and 
which, by means of a cover fufpended from it, can be 
fcrewed up before the diver enters the water. The jacket 
with Ihort fleeves, that cover the upper part of the arms, 
ferves to prevent the waterfront penetrating through the 
joining of the cylinders, where the one'is inferted into 
the other, as alio through the holes for the arms, as it is 
bound fad round both parts of the cylinder, and likewife 
round the arms. The cafe is the fame with the drawers, 
which are bound clofe round the knees. The internal 
diameter of the breathing tubes is three-fourths of an 
inch Rhinlandifh. They confid of drong brafs wire, 
wound into a fpiral form, and covered with drong leather. 
The refervoir, a, is for the purpofe of colledting the fmall 
quantity of water that might force itfelf into the breath- 
ing pipe when long ufed, and which otherwife would be 
in continual motion, and render breathing difagreeable. 
When the diver, after being made acquainted with all 
the parts of the machine, has put it on and fufpended 
from it proper weights to keep him deady, let him enter 
10Z the 
