DIVING BELL. 
the other edge was a rudder for steering. 
An aperture at the bottom, with its valve, 
was designed to admit water for the pur- 
pose of descending; and two brass forcing- 
pumps served to eject the water witliin 
when necessary for ascending. At the top 
there was likewise an oar for ascending or 
descending, or continuing at any particular 
depth ; a water-guage or barometer deter- 
mined the depth of descent, a compass di- 
rected the course, and a ventilator within 
supplied the vessel with fresh air when on 
the surface. 
The entrance into the vessel was ellipti- 
cal, and so small as barely to admit a per- 
son. This entrance was surrounded with a 
broad elliptical iron band, the lower end 
of which was let into the wood, of which 
the body of the vessel was made, in such a 
manner, as to give its utmost support to the 
body of the vessel against the pressure of 
the water. Above the upper edge of this 
iron band there was a brass crown or cover, 
resembling a hat with its crown and brim, 
which shut water tight upon this iron baud. 
The crown was hung to the iron band with 
hinges, so as to turn over sideways when 
open. To make it perfectly secure when 
shut it might be screwed down upon the 
band by the operator, or by a person with- 
out. 
. There were in the brass crown three 
round doors, one directly in front, and one 
on each side, large enough to put the hand 
through : when open they admitted fresh 
air; their shutters were ground perfectly 
tight into their places with emery, hung 
with hinges, and secured in their places 
when shut; there were hkewise several 
small glass windows in the crown, for look- 
ing through and admitting light in the day 
time, with covers to secure them. There 
were two air-pipes in the crown. A venti- 
lator svithin drew fresh air through one of 
the air pipes, and discharged it into the 
lower part of the vessel ; the fresh air in- 
troduced by the ventilator, expelled the 
impure light air through the other air pipe. 
Both air pipes were so constructed that 
they shut themselves whenever the water 
rose near their tops, so that no water could 
enter through them, and opened themselves 
immediately after they rose above the 
water. 
The vessel was chiefly ballasted with lead 
fixed at the bottom ; when this w'as not suf- 
ficient, a quantity was placed within, more 
or less, according to the weight/of the ope- 
rator ; its ballast made it so stiff, that there 
was no danger of its oversetting. The ves- 
sel, with ail its appendages and the ope- 
rator, was not of sufficient weight to settle 
it very low in the water. About two hun- 
dred pounds of the lead at the bottom for 
ballast could be let down forty or fifty feet 
below the vessel ; this enabled the operator 
to rise instantly to the top of the water in 
case of accident. 
When the operator would descend, he 
places his foot on the top of a brass valve, 
pressing it, by which he opened a large 
aperture at the bottom of the vessel, through 
this the water entered at his pleasure; 
when he had admitted a sufficient quantity, 
he descended very gradually ; if he admit- 
ted too much, he ejected as much as was 
necessary to obtain an equilibrium by the 
two brass forcing pumps which were placed 
at each hand. Whenever the vessel leaked, 
or he would ascend to the surface, he also 
made use of these forcing pumps. When 
the skilful operator had obtained an equili- 
brium, he could row upward or downward, 
or continue at any particular depth, with 
an oar placed near the top of the vessel, 
formed upon the principle of the screw, the 
axis of the oar entering the vessel ; by turn- 
ing the oar one way, he raised the vessel, 
by turning it the other way he depressed 
it. 
A glass tube, eighteen inches long and 
one inch in diameter, standing upright, its 
upper end closed, and its lower end, which 
was open, screwed into a brass pipe, through 
which the external water had a passage into 
the glass tube,' served as a water-guage or 
barometer. There was a piece of cork, 
with phosphorus on it, put into the water- 
guage. When the vessel descended the 
water rose in the water-gauge, condensing 
the air within, and bearing the cork with 
its phosphorus on its surface. By the light 
of the phosphorus, the ascent of the water 
in the gauge was rendered visible, and the 
depth of the vessel under water ascertained 
by a graduated line. 
An oar formed upon the principle of the 
screw was fixed in the fore part of the ves- 
sel; its axis entered the vessel, and being 
turned one way, rowed the vessel forward, 
but being turned the other way, rowed it 
backwards ; it was made to be turned with 
the hand or foot. 
A rudder hung on the hinder part of the 
vessel, commanded it with the greatest 
ease. The rudder was made very elastic, 
and might be used for rowing forward. Its 
tiller was within the vessel on the operator’,-; 
