CERTAIN IMPROVE- MENTS IN THE APPARATUS FOR MANUFACTURING, PURIFYING, AND STORING GAS
Year: 1817

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
PERKS, of Cary Street, in the Parish of Saint John Westminster, in the
County of Middlesex, Engineer, send greeting.
WHEREAS His most, Excellent Majesty King George the Third did,
by His Letters Patent under the Great Seal of the United Kingdom of
Great Britain and Ireland, bearing date at Westminster, the Fifth day of
August, in the fifty-seventh year of His reign, give and grant unto me, the
said John Perks, my exors, adñiors, and assigns, His special licence, full
power, sole privilege and authority, that I, the said John Perks, my exors,
adñiors, and assigns, should and lawfully might, during term of years
therein mentioned, make, use, exercise, and vend, within England, Wales,
and the Town of Berwick-upon-Tweed, my Invention "CERTAIN IMPROVE-
MENTS IN THE APPARATUS FOR MANUFACTURING, PURIFYING, AND STORING GAS;"
in which said Letters Patent there is contained a proviso that if I, the said
John Perks, shall not particularly describe and ascertain the nature of my
said Invention, and in what manner the same is to be performed, by an
instrument in writing under my hand and seal, and cause the same to be
inrolled in His Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said Letters Patent, that then
the said Letters Patent, and all liberties and advantages whatsoever thereby
granted, shall utterly cease, determine, and become void, as by and in
the same, relation being thereunto had, may more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
John Parks, do hereby declare that the following description, and the Drawings
annexed, do fully ascertain, explain, and set forth the nature of my Invention,
and how the same is to be made, constructed, arranged, and combined in the
most beneficial way that I know and make use of; and I hereby further declare
that my improvements are described under three distinct and separate heads or
departments, which are as follows, that is to say:-
The first department compises my improvements in the construction,
combination, and arrangement of a furnace for manufacturing gas from pit
coal.
The second department comprises and describes my improved method of
constructing, combining, and arranging certain pipes, chambers, &c., by which
means I produce an apparatus or vessel that more effectually condenses the
impurities contained in gas than has ever been accomplished before.
And thirdly, my applying an air vessel to a gasometer, which may be filled
with air or water, or by any proportions of each, in the manner and way herein
described, I can produce a more equal pressure upon the contained gas than
was ever before known or made use of, by which means gas may be more
conveniently stored and delivered than by the method now adopted, namely,
that of ballance weights and chains.
Drawing 1-Figure 1 represents a front elevation of thirteen retorts,
which is the number I find most convenient to set according to my improved
method of arrangement and construction. But my plan or method is capable
of considerable variety in point of numbers at the option of any manufacturer.
Each retort is numbered from one to thirteen, and each in this view has
its mouth piece A, A, A, A, and cover B fixed in the usual manner; that is to
, the mouth pieces are united to the retorts by bolts and nutts, and the
cover of each after being luted is fixed as usual by a screw attached to the
lever a, which passes through a female screw in the cross bar b, the cross bar
being retained in the position shewn in this Figure by each end slipping into
the loops C, C, which project from the mouthpiece A.
say,
To give a more complete description of the method of fixing on the
cover of each retort, Fig. 3 represents a section of the centre one, in
which 13 is the retorts; A, the mouthpiece; B, the cover kept in a proper
position by the screw attached to the lever a, which screw passes through the
centre of the bar b, whose ends are received in the loops C, C, projecting from
the mouth piece A. d represents the position of a gas pipe, which issues
from the side of the mouthpiece A; the whole being exactly similar to what
is used in the present practice of manufacturing gas froni pit coal. From

page_text: the side of the mouthpiece of each retort, see Fig. 1, issues a gas pipe in the
usual manner, except that in this case they are bent in such a direction that
room may be obtained to remove the covers of the mouthpiece more readily
for the purpose of charging and discharging the retorts, as occasion may require.
It may be here observed, that the gas pipes which issue from the retorts
6, 7, and 18, do not stand in the same plane as the others, but project about
6 inches before them, by which means sufficient room is obtained to remove
the covers B, B, B, B, and likewise to effect this more easily the parts of
those pipes seen at d, d, d, are made elliptical, for the purpose of keeping the
internal area the same as the other parts, while the narrowed form thus
produced gives greater facility in removing the covers before named. C, C,
represents a cast-iron ring, within which the whole of the retorts are placed;
there is a similar ring at the back part of the furnace, but it is about 8 inches
less in diameter. The two are placed opposite and parallel to each other,
and kept in that possition by four bars, the ends of which are seen formed into
screws at e, e, e, e, and mado fast to the front ring C, C, by four nutts. The
position of these four bars, and the shape of each, will be more distinctly scen
in Fig. 2, which represents a section across the centres of the retorts in their
combined state. In this view. it may be seen that twelve of the retorts form
a complete circle, which may be considered as one large cylindrical vessel,"
divided into twelve equal parts; the lines that seperate each retort from its
adjoining one being all radii of the circle. E, E, represents a circle of
brickwork, which incloses the whole of the retorts, leaving the space F, G, H, I,
around them. This is divided into four compartments by the Welch lumps
f, g, h, i, which project internally from the brick circle E, E, until they are
received by the bars e, e, e, e, which serve as frames to support and hold them
fast in their position. It is to be here observed, that the Welch lumps marked
f, g, h, i, and k, reach completely from the front to the back of the furnace,
being let into the front and back walls about four inches. 13 represents the
position of the central retort which is circular, having four small filletts cast
upon its outer surface, to lay or slide in the groves of the bars, which serve
as frames to hold the Welch lumps j, k, l, m. The office of these frames and
lumps is to divide the space J, K, L, M, into four equal parts, all of which
are to be used as flues. The lumps and m do not reach much more than half
way from the back to the front of the furnace, the opening left by this means
forming the connection between the upper and lower internal flues K, M,
and J, L; and to prevent the lumps and m from sinking down when in a
heated state, the sides of the bars r, r, which constitute frames to hold the lumps
Z and m, have a small projecting fillet, which fits into a corresponding recess

page_text: in the retorts 3, 4, and 9, 10. The dotted line N, O, divides the whole circle
into two equal and similar parts, each half being heated by a seperate fire.
The space I represents the lower external flue, into which the flame and heat
from the fire is first conducted, beginning its passage from the front of the
furnace. It then travels to the back, and turning over the back ends of the
retorts 4, 5, and 6, it comes towards the front in the lower internal fluo M,
and as the stop or lump m reaches only half way from the back to the front,
the flame passes over the end m, and pursues it course along the upper
internal flue K, until it reaches the back a second time, where it turns over
the back ends of the retorts 1, 2, and 3, taking then a front direction in the
upper external flue G, at the end of which, and in the front of the furnace,
it passes the register, and enters the flue constructed for its escape. What
has been here stated equally applies to the other side of the circle, cach half
being a duplicate of the other, and each half being heated by a separate fire.
To render the whole combination more evident, and the position of the parts
more intelligible, Drawing 2, Fig. 1, represents a plan of the furnace, with
three fourths of the upper half of the brick circle E removed; the remaining
part being that which contains the exit flue for one side of the circle; its position
is seen at P. To shew the internal structure more perfectly the retorts
10, 11, and 12, are in this Figure removed, by which means the length of
the dividing stop 7 is seen, which separates the upper from the lower internal
flue. The situation of the bars e, e, e, are more plainly seen, shewing how
they unite the front circular ring C, by means of the bolt and nut q, to the
back circular ring R, forming when united a skeleton or frame to place the
retorts within, and when so placed the whole forms the frustrum of a cone,
cach retort being about one inch smaller at the back than at the front, by
which means any one of them may be withdrawn separately, and replaced
by another in case of partial wear or accidents.
Fig. 2 represents a plan of the back circular ring R, shewing the recesses
P, p, &c., in which the back ends of the retorts are placed, being supported
and kept in their position by the projecting ribs or fillets s, s, &c. The back
of this ring is completely covered with Welch lumps, which are fixed to the
ring by projections shewn at t, t, &c., made to fit the dove-tailed apertures
v, v, &c. The recesses seen at v, v, are filled by projecting pieces on the back
end of each retort, by which means the whole will be firmly united and bound
together when the retorts are in their places. w represents a dove-tailed
aperture, of a wedge-like form, the sides of which converge to the centre of
the ring. represents a lump placed in its aperture, but not pushed home
to its proper bearing. t, t, t, &c. represent the other Welch lumps, driven

page_text: home to their proper position, leaving the recesses v, v, &c., which will be filled
by corresponding projections upon the ends of each of the external retorts. For
the convenience of the workman the ring R may be cast in four quarters, and
united by the screws 7, 7, 9, &c., and the projections y, y, &c., inclose and
hold between them the ends of the bars e, e, e, e, by which this ring is united
to the front ring c, Fig. 1, Drawing 1, forming thereby a skeleton or frame to
hold the retorts within. The Welch lumps f, g, h, i, envelope the bars e, e, e, e,
serving thereby to defend them from the action of the fire, which would
cause them to decay before the Welch lumps were destroyed if not preserved
by these means.
Fig. 3 represents an edge view of Fig. 2, in which the thickness of the
Welch lumps may be more plainly seen. Fig. 4 represents a plan of one
of the lumps separated from the ring R, the dove-tailed projection appearing
at t. Fig. 5 represents a section through the dotted line shewn upon Fig. 4.
In Fig. 1 the projecting fillet or rib (s) may be scen let into a recess, formed
in the retorts 1 and 2; similar recesses are constructed in all the other, to
receive the remaining ribs of filletts, which are shewn at 8, 8, 3, &c. in
Fig. 2.
Drawing 8.-Fig. 1 represents a section through the centre of the furnace,
by a plane perpendicular to the base, and in the direction of the dotted
line N, O, seen on Fig. 2 of Drawing 1. Q, Q, represent a section of a
cast-iron ring, which is supported in the position here shewn by the bars
t, v, u, w, which bars are the frames that hold the lumps j, k. These have
been shewn in Fig. 2 of Drawing 1. The centre retort 13 is placed in the.
middle of this inner ring, resting upon the lump k and the retorts 6 and 7.
Fig. 2 represents a section of the furnace by a plane perpendicular to the
S shews
base, and in the direction of the line n, o, see Fig. 2, Drawing 1.
the position of the fireplace, with the ash-pit under it. From the fire.the
flame goes in the direction of the darts, until it reaches the lower external
flue I, at which place it first comes in contact with the external sides of the
retorts 4, 5, and 6. By following the direction of the darts it may be traced
to the lower internal flue M, and having traversed it, the next course is round
the end of the stop m, and into the upper internal flue K, and passing along
this it turns round the ends of the retorts 1, 2, and 3, to gain the upper
external flue, from which it escapes by passing the register, as shewn in the
Plan Fig. 1, Drawing 2. It may be here observed, that the state of the fire
may at all times be examined by means of the sight holes, shewn at T, T, in
Fig. 1, of Drawing 1, and adjusted by the registers seen at V, V. And I
hereby further declare, that I make use of a hydraulic main in the usual

page_text: manner that is practised in the manufacture of gas from pit coal, having made
made no improvement in that part of the system. But I shall here observe
that I prefer placing it behind the gas pipes which issue from the retorts, as
being a more convenient position when applied to my improved arrangement
and combination. The whole of the Drawings that are annexed to this depart-
ment of my improvements are made to a scale of one inch to a foot, and the
retorts are each of sufficient capacity to hold and carbonize two. bushels of coals.
And I hereby further declare that I do not claim as my Invention either
fireplaces, retorts, gas pipes, or any of the parts of this department when
taken individually, nor any of the minor combinations which existed and were
used before this Patent was granted. My improvements; consist in giving to
any convenient number of retorts when combined and arranged (as I have de-
scribed) a cylindrical form, by which means they become as it were one large vessel,
divided by their sides into separate compartments, and by separating the spaces
contained within the cylinder of retorts, and forming others on the outside,
I am enabled to convey the flame and beat from the fireplace in the direction
I have described, which, owing to this arrangement, construction, and com-
bination, produces economical and beneficial effects; never before known
or made use of. And I hereby further declare, that the parts of this
combination consist of cast iron or other suitable metal for the retorts, mouth-
pieces, bars, pipes, &c, and those parts which divide the spaces into separate
flues are marle of the material called Welch lump, which may be moulded
into the various formis and shapes I have described in the Drawings, and for
the rest I prefer and do make. use of the best iron. Such bricks for all
the parts that are much exposed to the heat, and for the external parts,
any good sort of brick or other suitable materials which can be best obtained
in the situation where this structure may be erected.
The second department of my Invention consists in combining, arranging, and
constructing a number of cast-iron or other metal pipes, in such manner and
order that when they are fixed in a proper vessel they may be completely immersed
in cold water, by which means they will very greatly assist in cooling, condensing,
and thereby purifying the gas produced from pit coal for the purpose of lighting
houses, streets, &c., if the said gas be made to pass through them after, it leaves
the hydraulic main. It being a well-known fact that much of the, impurities
contained in coal gas are volatile at a high temperature, consisting principally
of coal tar and ammoniacal. liquor, my great object has been to construct;
combine, arrange, and place, in the order and manner hereafter to be described,
a number of pipes or tubes, through which the gas is made to pass, and being
cooled in its passage it deposits. a larger portion of its impurities than has been

page_text: effected by the imperfect means made use of in the present practice. I have
likewise contrived a suitable number of chambers to receive the condensed
impurities as soon as they are formed in each pipe; and although the gas has
to pass through at least three hundred feet of pipe, the condensed impurities
will never have to run above ten or twelve feet before they are collected into a
general receptacle. By this improvement a larger portion of tar and ammonia
will be prevented from passing into the lime vessel, consequently they will be
collected in a marketable state, and the solution of lime used for completeing
the purification will exert its chemical powers with increased effect and for a
greater length of time, owing to the gas, being freed from so large a portion of
its impurities.
Drawing 4.-Fig. I represents a perspective view of a condensing vessel, with
a front and side row of condensing pipes fixed to the upper bottom. plate B..
The flanches a, a, are made fast in the usual way by bolts and nutts which
pass through the plate B and flanches a, a, &c. A shews the inlet pipe,, into
which the gas is conducted from the bydraulic main. This pipe is seen bolted
to the plate B, which plate has as many holes in it as there is condensing
pipes, each being exactly equal in diameter to the internal bore of a condensing
pipe. By this contrivance the gas descends into the chamber C, which
chamber receives and retains the condensed impurities that, were; formed in
the pipe A. The gas then ascends from the chamber C up the pipe: D; and
the second portion of the impurities being condensed fall into the chamber C,
and are then retained, as before described. The gas having ascended to the
top of the pipe D, turns over the bend E, and descends the pipe F, entering
the second chamber G, where it deposits a third time, its condensed impurities.;
after which it ascends the pipe H, and as the pipes, bends, and chambers. arc
united throughout in the same manner, it must necessarily pass through the
whole system, each chamber receiving the impurities condensed in two pipes..
Fig. 2 represents a perspective view of the whole of the pipes, and they appear.
when fixed to the middle, or upper bottom plate B of Fig. 1. The passage of
the gas may be traced from the entrance of it at the pipe A until it has passed
through the whole of, the pipes, making its exit at. I. It is then conducted in
the most convenient way to the lime vessel to complete the purification in the
usual way. It may now be clearly conceived that the great deposit of impure
materials that are thus extracted, from the gas by cooling and condensing: will
greatly lessen the labour of the lime solution, which, will prove, an object: of
considerable importance in the manufacture of gas from pit coal. The dotted
lines and darts in each Figure represent the direction of the gas in its passage
through the pipes and chambers, and by following their course it may be traced

page_text: from the inlet pipe A to the exit pipe I, having traversed the whole of the
pipes in its passage. b, b, represent the flanches that serve to unite the pipes to
the bends K, K, &c. These are fixed by the usual method, namely, bolts and
nutts, the common iron cement or any suitable packing being previously
placed between each to keep the joints close. And it may be here observed,
that the flanches are made of such a diameter, that when the whole are united
together within the vessel, they mutually rest against each other, and prevent
any lateral motion, which would disturb and loosen the joints at the bottom of
the pipes. The external form of the vessel may be seen in Fig. 1, the sides
thereof being cast in seperate pieces, with flanches on each, by which they are
afterwards bolted together, the joints being made secure by any suitable
cement or packing put between each. The top plate L serves to unite the
sides more firmly, but the vessel may be made open at the top if it be required.
And be it observed, that the condensations will be greatly assisted if a stream
of water enter at M, and rising through the whole space between the pipes
makes its exit at N. This will insure the immersion of all the pipes and bends.
It may be seen at c, c, that the sides of the chambers have an aperture in
cach, by which means the whole communicate with each other, and to render
each chamber air-tight, water is let in sufficient to fill the under part of the
chambers as high as the line y, z, and the whole is fit to be put into action.
When the condensations rise nearly to the top of each chamber, they will be
drawn off to the pipe Q, which may be directed to any convenient receptacle.
Fig. 3 represents a plan of the upper side of the plate B, upon which the
condensing pipes are fixed, the circles shewn at a, a, &c. being cast thicker
than the other parts of the plate, for the purpose of receiving the flanches at
the bottom of the condensing pipes. Fig. 4 is a plan of the under side of the
chambers, inclosed by the sides of the condensing vessel. d, d, d, &c. repre-
sent holes in the tops of each chamber, through which the bolts are put that
fix the flanches of the condensing pipes to the plate B, as shewn in Fig. 1.
The whole of the chambers are cast in four pieces, the separate parts being
shewn by the dotted lines e, e, f, f, g, g, h, h; and when the whole is put
together, the joints are made secure by iron cement in the usual manner.
Fig. 5 represents an end elevation of the chambers, with fragments of the
condensing pipes fixed, to shew more perfectly how the whole is put together,
the method of doing which I will now explain. B represents the upper bottom
plate, supported by the sides R, R; the parts which form the chambers are
then placed in a proper position, previous to which a coat of iron cement is
covered over the upper surface of each division or parts; the bolts are then
put through the holes in the chambers and the corresponding ones in the

page_text: late B, and the flanches a, a, &c. being placed over them, the whole are
united by the nuts being screwed tight. When one row of the pipes are fixed
to the bottom plate B, the bends are to be fixed on the upper parts of the
pipes, as shewn in Figures 1 and 2. The joints at the top of the pipes must
be secured by cement in the same manner as has been described before. I
will here observe, that when one division of the chambers are fixed, the joints
should be very carefully made sound by working the iron cement into all the
crivices until every part is made perfectly air-tight. The bottom being secured
by bolts in the usual way, the last parts to be fixed are the sides above the
plate B; the flanches for this purpose will be seen in the Figures 1 and 3. The
direction of the gas in its passage will be seen by the dotted lines and darts on
Fig. 5, which explains more clearly how each chamber receives the conden-
sations of two pipes; and it must be here observed, that this Figure is an
elevation of the side S, T, of Figure 1, the outer part of the vessel being
removed to shew the chambers. And further to identify the improvement I
have invented in this department of the process for manufacturing gas from pit
coal, I hereby declare that the beneficial effects I have described arise entirely
out of and are produced by the combination and arrangement of the parts of
which my condensing vessel is constructed, and not by using any particular
material to form the combination with, for the same combination may be made
with various metal or earthen pipes, or metal and earthen pipes and chambers
united. But the same beneficial effects cannot be produced, whatever the
materials may be, except the combination and arrangement be the same as I
have described. And I hereby further declare, that the shape of the con-
densing vessel and the number of pipes may be varied at pleasure, observing
always that the greater number of pipes the more perfect will be the condensa-
tion, and consequently the better will the gas be purified previous to its
entrance into the lime vessel.
And I further declare, that I do not claim any of the parts individually of this
department of my improvements, nor any of the minor combinations which
existed and were used for a variety of purposes before this Patent was granted.
My Invention consists in the whole combination and arrangement by which
an apparatus or vessel is constructed, capable of producing more beneficial
effects in the condensing and purifying of gas than was ever before known or
made use of.
The third department of my improvements in the method of storing and
delivering gas consists in attaching, fixing, and combining certain apparatus to an
air vessel or vessels used for the purpose of buoying up a gasometer, by the use of
which the buoyancy may be increased or decreased at pleasure, without the use

page_text: of balance weights and chains. By the use of this combination a more equal
pressure may be obtained upon the gas inclosed, which will be greatly advan
tageous both in the operation of receiving and storing the gas, and likewise in
delivering it from the gasometer into any main or pipe for the purpose of
increasing or decreasing the pressure upon the gas, either in storing or
delivering. The air vessels which I make use of are so contrived that water
may be let into them by opening a valve and a corresponding quantity of air
let out, by which means the buoyancy of the vessel may be decreased, and the
weight increased, until the precise degree of pressure required is obtained.
And for the purpose of increasing the buoyancy I have invented and con-
trived a method of applying a syphon pipe, which will draw of any quantity
of the water contained in ny air vessel, and by letting in more air the buoy-
ancy of the vessel may be increased in any degree within its capacity.
Fig. 1, Drawing 5, represents an internal view of one half of a gasometer, of
the common shape and construction, with an air vessel attached all round the
internal part of the bottom; a section of the air vessel may be seen at A.
The method of fixing it to the gasometer will be explained hereafter. The
braces E, E, E, E, are keyed at their lower ends to the bands of the air
vessel, and bolted to the ring F, by which they support the roof of the
gasometer, the whole weight of which rests upon and is buoyed up by the
air vessel, except what arises from the buoyancy of the gas inclosed. B, B,
represents a metal pipe, which comes through the top of the gasometer and
enters the air vessel at b. This pipe incloses an iron rod, which has a screw
on its upper end at c. The screw works in a box or nutt, which box or nutt
being turned round by a lever elevates the rod c at pleasure, and closes tlic
plug of the valve d. The valve is represented as being open to receive water,
which passes into the air vessel through the appertures in the side of the
chamber of the pipes B, B, scen more distinctly in Fig. 2. By the admission
of water the weight of the whole combination will be augmented, and when
this is sufficiently attained, the rod c is elevated and the valve closed; of course
this will produce a greater pressure upon the gas in the gasometer. The pipe
C is for the purpose of drawing any quantity of water from the vessel A that
may be necessary to increase the buoyancy; and to effect this the pipe C
passes through the air vessel and dips nearly to the bottom, as may be scen
at f. Upon the upper part of the pipe at g, another pipe is screwed, which,
descending below the bottom of the air vessel, may be used as a syplion to
draw of any quantity of water that may be required; and to prevent a vacuum
being thereby formed, the pipe D is inserted to supply a corresponding
quantity of air. Fig. 2 represents a cross section at the air vessel upon a

page_text: larger scale, in which the method of fixing it to the sides of the gasometer
will be more plainly seen. h represents part of the side of the gasometer A, A,
the air vessel fixed to its position by the iron strap k, k. The end of the
strap k, k, is formed into a staple or loop, through which the bar m is put to
receive the loop on the end of the brace E. These parts are made fast by the
pin n, which is put through a hole in the bar m. The whole of the parts are
made fast to the side of the gasometer by the bolt o, which passes through
h, m, and k, the nutt p binding all firmly together. Fig. 8 represents a section
through the center of a globular air vessel, which may be applied to either
large or small gasometers. This vessel may be made of any thin metal. I.
prefer iron, and the best way to construct it will be to form it in two hemi-
spheres, each of which must be made of several pieces, united with rivets in
the usual way adopted by workers in metal. The two halves are joined by
flanches, as seen at I, q. r represents a section of an iron ring, of the same
diameter as the flanches 9, 7. The bolts and nutts which unite the flanches
pass through the iron ring, and fix the whole firmly together. The iron ring
gives great stability to the vessel, and forms a very secure hold for the braces
which are to retain it in a proper position. E, E, &c. represents four of six
braces (the other two being removed), which are fixed to the flanches of the
air vessel at 7, 9, and to the roof of the gasometer at 8, 8, 8, 8. These braces
are placed at equal distances round the air vessel, and each has a horizontal
and a diagonal stay or brace bolted to it, as seen at t, t. The diagonal braces
are continued upwards until they reach the extremity of the roof, where each
is made fast with a bolt and nutt. The horizontal braces are bolted to
the sides of the gasometer, the whole weight of which floats, and is buoyed up
by the air vessel. The pipes and other parts in this Figure, which perform
the same office as in Figs. 1 and 2, are denoted by the same letters, there
being no variation in any part except for the purpose of accommodating it to
the different shape and position of the air vessel. And I here observe, that
either of these vessels may be used in the same manner as if it was an open
vessel, by leaving the valve unclosed, in which case the syphon pipe C and the
air pipe D must be furnished with means to render them air-tight. The
manner of doing this will be seen in Fig. 5, which represents a section of the
air pipe D, with a cap screwed down tight upon a collar of leather to make
the joint air-tight. This method will be particularly useful in case of a trifling
leakage, because the entrance of more water would be opposed by the resist-
ance or elasticity of the air included in the vessel. And be it likewise observed,
that in those cases where it may be found necessary to alter the adjustment
frequently, I fix stopcocks upon the syphon pipe, or both it and the air pipe,

page_text: in the manner shewn in Fig. 6, by the use of which the weight of the air
vessel may be increased or diminished at pleasure. I shall here observe,
that in constructing the air vessel for any gasometer, the first thing to be
ascertained is, the weight of all the parts of the gasometer, which, being done,
the air vessel must be made of sufficient capacity to contain a quantity of air
equal to half a pint for every pound weight of the materials of which the
gasometer and air vessel is constructed. Fig. 4 represents the upper part of
the valve pipe on a larger scale. C shews the valve rod, which is clevated by
turning the nutt v, the said nutt being confined in the collar u, u, which is
screwed to the roof of the gasometer w, w, by bolts and nutts. And I hereby
declare, that the apparatus which I have invented and herein described may
be applied to a great variety of air vessels, which will be easily understood by
the two that I have explained, each being very disimilar in shape and position.
And I hereby further declare, that I do not claim the exclusive right of using
an air vessel to buoy up a gasometer, air vessels having been used before by
other persons for the same purpose. My Invention in this department con-
sists in combining, applying, and fixing to an vessel or vessels, in the manner
and order herein described, certain apparatus, consisting of a valve rod' and
pipe, a syphon pipe, and an air pipe, by the use of which the buoyancy of an
air vessel may be varied at pleasure by very easy and simple means, producing
very great advantages and improvements in the practice of storing and
delivering gas.
In witness whereof, I, the said John Perks, have hereunto set my.
hand and seal, this Fourth day of February, in the year of our
Lord One thousand eight hundred and eighteen.