THAT BY THE APPLICATION OF COMPRESSED AIR POWER AND MOTION CAN BE COMMUNICATED TO FIXED MACHINERY, AND TO CARRIAGES AND OTHER LOCOMOTIVE MACHINES, AND TO SHIPS, VESSELS, AND OTHER FLOATING BODIES
Year: 1829

page_text: MANND SPE
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MANN, of Effia Road, Brixton, in the Parish of Lambeth, in the County of
Surrey, Gentleman, send greeting.
WHEREAS His present most Excellent Majesty King George the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the First day of June, in the tenth year of His reign, did, for
Himself, His heirs and successors, give and grant unto me, the said William
Mann, by the description of William Mann, of Effia Road, Brixton, in the
Parish of Lambeth, in the County of Surrey, Gentleman, His special licence,
that I, the said William Mann, my exors, admñňors, and assigns, and such
others as I, the said William Mann, my exors, admors, and assigns, should
at any time agree with, and no others, from time to time and at all times
during the term of years therein expressed, should and lawfully might
use, exercise, and vend, within England, Wales, and the Town of Berwick-
upon-Tweed, and also within all His Majesty's Colonies and Plantations
abroad, my Discovery "THAT BY THE APPLICATION OF COMPRESSED AIR POWER
AND MOTION CAN BE COMMUNICATED TO FIXED MACHINERY, AND TO CARRIAGES
AND OTHER LOCOMOTIVE MACHINES, AND TO SHIPS, VESSELS, AND OTHER FLOATING
BODIES;" in which said Letters Patent there is contained a proviso obliging me,
the said William Mann, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of my said Invention or
Discovery, and in what manner the same is to be performed, and to cause
the same to be enrolled in His Majesty's High Court of Chancery within
six calendar months next and immediately after the date of the said recited
Letters Patent, as in and by the same, reference being thereunto had, will more
fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I,-the-said
William Mann, do hereby declare that the nature of my said Discovery, and
the way and manner in which the same is to be carried into effect and per-
formed, is described and ascertained as follows (that is to say): :-
The way or means by which I communicate power and motion to fixed
machinery, and to carriages and other locomotive machines; and to ships,
vessels, and other floating bodies by the application of compressed air, is by
using atmospheric air to form, or assist to form, a depositary of mechanical
power, by the aid of which_the_power_generated and produced by steam
engines, windmills, water mills, treadmills, and other machinery may be
packed and made portable, so as to be afterwards used for propelling machinery
at any time or place, however distant. The plan proposed is to employ all or
any of the before-mentioned cheap generators and, producors of mechanical
power to compress into wrought iron or other reservoirs that are capable of
sustaining the pressure of the elastic fluid at the required density. a. number of
volumes of atmospheric-air; and when the air. so compressed is afterwards
permitted to expand to its previous volume, then the power employed in the
compression thereof will be obtained again by its expansion, when such expan-
sion is made to take place-in-and-through-such machinery,-as-will-be hereafter
more particularly described. The method by which mechanical power is to be
packed up and made portable so as to communicate power and motion to
fixed and locomotive machines at times and places distant from where the said
power is generated and produced is, first, by the employment of a series of con-
densing pumps, constructed and arranged on an improved principal, in and
through which the air is to be compressed,.then. very little, if any, of the
power employed will be wasted or lost during the process of condensation;
and as the advantages to be derived from thus transferring mechanical power
depends on the construction and arrangement of the condensing pumps and
other machinery employed, the improvements made in the construction and
arrangements of such pumps will be now described (as follows):-
The condensing pumps used in compressing the air I make of different
capacities, according to the density of the fluid to be compressed, those used to
compress the higher densities being proportionably smaller than those pre-
viously employed to compress it at the first or lower densities; that is,-suppose
the air was to be raised to the required density by compressing three volumes
into the space of one in each of a series of pumps, then the second pump on the
series must have only one third of the capacity of the first, the third pump
only one third of the capacity of the second, and so of the rest, if more than
three are employed. If the density is to be raised by compressing four

page_text: volumes of air into the space of one in each of a series of pumps, then the
second pump in the series must have only one fourth of the capacity of the
first, the third pump one fourth the capacity of the second, and so of the rest.
If, again, the density is to be raised by compressing only two volumes into
the
space of one in each pump, then each succeeding pump in the series must
be only half the size or capacity of that which proceded it. By adopting
this method of compressing air it will be seen that it may, without difficulty,
be compressed to a thousand atmospherics, if required.
To show more fully the advantage of this method of comprossing air or
other clastic fluids, suppose it was required to compress a quantity of air to
twenty-seven atmospheres by compressing three volumes into the space of one
in each pump, this will be effected by compressing three volumes into one in
each of three pumps instead of compressing twenty-seven volumes into the
space of one in a single pump, as by the method at present adopted in com-
pressing gas and other elastic fluids. To render this more apparent, the
following detail of the process is given:-Let each pump be twenty-four
inches in length, to be worked on a three-throw crank; let the area of the first
pump
be 90 square inches, then the area of the second must be 90÷3-30
inches, and the third 30+3=10 square inches; the first pump twenty-four
inches in length, and having an area of 90 square inches, its capacity will be
24×90 2160 cubic inches; it will, therefore, at each stroke of the piston
receive into the cylinder 2160 cubic inches of air at its natural pressure of
about fifteen pounds on the square inch, and by compressing three volumes
thereof into the space of one in that pump the bulk will be reduced from two
thousand one hundred and sixty to seven hundred and twenty cubic inches,
and the density consequently raised from the atmospheric pressure of about
fifteen pounds on the inch to that of there atmospheres of forty-five pounds on
the inch, thereby giving to such air an available mechanical power or force
equal to thirty pounds on the inch. The second pump being of the same length
as the first, but having an area of only thirty square inches, its capacity will
be 24x80=720 square inches; it will, therefore, at each stroke of the piston
receive into the cylinder the 720 cubic inches of the air previously compressed
to the density of three atmospheres by the first pump, and by also compressing
three volumes of that condensed air into the space of one bulk will be reduced
from 720 to 240 cubic inches, and the density thereby raised from three to nine
atmospheres, that is, from a pressure of forty-five to a pressure of one hundred
and thirty-five pounds on the inch, that second pump giving to the fluid a
further mechanical power or force of ninety pounds on the inch. The
third pump in the series being of the same length as the others, but with an

page_text: area of only ten square inches, its capacity will be twenty-four Xten=240
cubic inches. It will, therefore, receive into its cylinder at each stroke of the
piston the two hundred and forty cubic inches of air previously compressed to
nine atmospheres, and by also compressing three volumes of that condensed air
into the space of one will reduce the bulk from 240 to 80 cubic inches, and
further raise the density from 9 to 27 atmospheres, that is, from a pressure of
one hundred and thirty-five to that of four hundred and five pounds on
the inch.
The following Table will exhibit, under one view, the arrangement of the
pumps, as above described, shewing the increasing density as the fluid passes
through the several pumps (see Table No. 1. in the margin):
By this arrangement it is seen that the pressure in each pump is precisely
the same. This, however, takes place only when the density is just twenty-
seven atmospheres, for previously thereto the pressure on the piston of the last-
pump will be less than 2700, and afterwards it will be more, increasing by
one eighteenth for every additional atmosphere, so that at thirty atmospheres
the pressure in that last pump will be three thousand one hundred and fifty-
pounds, while the pressure on the other two will continue at two thousand.
seven hundred pounds. Suppose, again, it was required to raise a quantity of
air to the density of sixty-four atmospheres by compressing four volumes into
the
space of one in each of a series of pumps instead of compressing it by the
present method of sixty-four volumes into the space of one in a single pump,
then the capacity of each succeeding pump must be diminished by a ratio of

page_text: four, the first pump would then raise the deusity to four atmospheres, the
second to 4×4=16, and the third to 16×4=64 atmospheres; let the three
pumps be each be twenty-four inches in length, the area of the first one
hundred and sixty square inches, the second forty square inches, and of the
third ten inches, the air would then pass through the pumps as seen in the
Table No. 2. in the margin.
From the preceding Table it appears that each piston gives a uniform
pressure of seven thousand two hundred pounds through the last six inches of
the stroke, and a fluxionary pressure from 0, or nothing, and increasing to
seven thousand two hundred pounds through the first eighteen inches. Now,
suppose the same quantity of air was to be compressed to the same density of
sixty-four atmospheres in the first pump, according to the method at present
in use, by rejecting the aid of the two auxilliary ones, then the piston would
require the enormous pressure of one hundred and fifty-three thousand six
hundred pounds, that is, upwards of sixty-seven tons, to carry it through the
last sixty-fourth part of the stroke, and a fluxionary pressure from 0 to one
hundred and fifty-three thousand and six hundred pounds to carry it through
the first sixty-three parts of each stroke; this is found by multiplying nine hun-
dred and sixty, the pressure of the air per inch when at sixty-four atmospheres,
by one hundred and sixty, the area of the piston, as 960 × 160=153,600.
This inconvenience is but partially removed by using a number of smaller
pumps on the same principle, say six pumps, making together the same area
of one hundred and sixty inches, then the pressure would be twenty-five thou-
sand six hundred pounds through the last sixty-fourth part of the stroke of

page_text: each piston; but that immense pressure is only a part of the inconveniencies
and disadvantage of the present-method, for, by compressing sixty-four volumes
into the space of one in a, single pump, the quantity of fluid to be forced
through the apertures and valves into the reservoirs at each stroke of the
piston is so very small, that with the best constructed machinery a considerable
part thereof will not pass the valve, but must inevitably remain behind, and'
return to atmospheric pressure in the cylinders on the reaction.of.the-piston,
and the whole of the power previously expended in compressing that part will
be totally lost. Now, suppose the same quantity of air was to be compressed
to the same density of sixty-four atmospheres by six pumps constructed and
arranged on the improved plan, this would be done by compressing only
two volumes into the space of one in each of the six pumps, then the maximum
of pressure, instead of being twenty-five thousand six hundred pounds on the
piston of each of the six pumps, would be only two thousand four hundred in
each. But then that pressure, instead of being through, only one sixty-fourth
part, it would be through the last half of each stroke, as will be seen in the
following Table. Let the length and area of the first pump, be the same as
the 'one in the preceding Table, and the same as the last-mentioned six pumps
when added together, that is, the length twenty-four inches, and the area
one hundred and six inches; then the operation and result will be as seen in
i

page_text: It is not pretended but that, strictly speaking, the same absolute quantity of
power is required to compress a given quantity of air by the one method as
by the other; what is meant to be understood is, that by the method adopted at
the portable gas and other works more than half the power employed is wasted.
This is evident on considering the small quantity of gas that can be compressed
per day by a ten horse power engine; yet gas is never attempted to be com-
pressed above thirty atmospheres. The improved method is capable of a variety of
modifications. A great part of the advantages would be obtained by using only
two pumps; for instance, suppose it was required to compress any elastic fluid to
a density of thirty-six atmospheres, it would be done on this principle in the two
pumps by compressing six volumes into the space of one in the first pump, and
thereby raising the density to six atmospheres, and then by the second pump
having only one sixth of the area of the first, then by six volumes being com-
pressed into the space of one in that pump the density will be raised from six
to thirty-six atmospheres. The preceding estimates for compressing air do
not go beyond sixty-four atmospheres, that being as high as will probably
be over required for locomotive machines. But when it is required for a pro-
jectile force, then by following the principle of reducing the area of the pumps
as the pressure on them is increased it will be raised to a density of one thou-
sand and twenty-four atmospheres by five pumps, on the plan of compressing
four volumes into the space of one in each pump, as follows:-Pumps 1st, 2d,
3d, 4th, 5th; number of atmospheres of compression, 4, 16, 64, 256, 1024.
When the density is raised by compressing only two volumes into the space of
one in each pump, then it will require ten pumps to increase the density to
1024 atmospheres, as follows:-
Pumps, 1, 2, 3d, 4th, 5th 6th, 7th, 8th 9th 10th.
Number of atmospheres of compression, 2, 4, 8, 16, 32, 64, 128, 256,
512, 1024.
To each of the condensing pumps,except the last, I add a small reservoir for
the purpose of receiving the air when compressed through such pump, and
for conveying it afterwards to the next pump in succession. In the aperture
through which the compressed air passes from the cylinder of the pump to its
reservoir there must be a valve to close and prevent the compressed air from
returning into the cylinder of the pump on the reaction or ascent of the piston ;
but no valva will be necessary in the aperture of the following dump through

page_text: :
wards towards the bottom of the cylinder, as is the usual way, then the supply
of air must be above the piston, and near the top of the cylinder. There must
also be an aperture and valve in the pistons of the pumps to permit the air
above to pass through into the vacuum below, when such piston is ascending;
should the pumps be made to press the air upwards then of course the supply
must be from below. If they are constructed to act both upwards and down-
wards, like the double acting steam engine, then the supply must be from
above and below alternately. The last pump in the series will convey the
compressed air into the large reservoirs for use; or, if conveyed by pipes as
hereafter-mentioned; then the air, when compressed, -may--be- conveyed-
directly into those pipes, and by those pipes conveyed into such last-mentioned
reservoirs, or the reservoirs of the locomotive machines, might be charged
directly from the pipes without the intervention of any reservoirs. The reser-
voirs for containing the compressed air are constructed on the-same principle.
as those invented and used for containing portable gas, which are so well known
that they need no further description. The cylindrical ones, made of maleable
iron, are so perfectly adapted for this purpose that they appear scarcely to
admit of improvement. The most useful and convenient lengths and diameters
for almost any purpose appear to be from four to five feet in length, and from
nine to twelve inches in diameter, except when required to contain air at very
high densities for projectile force, then the diameters should be from three
to six inches, as that will then be the most convenient and manageable size
and weight; and the thickness of the metal, and the consequent strength of
the reservoirs, may be calculated from the known tenacity of the metals
of which they are formed, the area of the reservoirs and the density of the
fluid being previously given. The strength of the reservoir should not be much
less than three times the product of such calculations. The portable gas
reservoirs used for containing thirty atmospheres of gas will give, on calculation
founded on such data, a strength equal to one hundred atmospheres; but even
the allowance of three times the estimated tenacity of the metals should not be
wholly relied on, for there may be flawes in the metal, or imperfections in the
joints or other workmanship; they should, therefore, be subjected to a proof
equal to nearly twice the pressure they are intended to bear in use. The best
method of obtaining the power again from the compressed air is by permitting.
it to expand in a cylinder similar to a cylinder of a steam engine, and to propel
a piston precisely in the same way that high-pressure steam propels it by its
expansion, and which expansion is caused and permitted by the supply being cut
off at a half, a third, or a fourth of the stroke, according to the elastic power of
the steam; in fact, the compressed air is to be used as an engineer would use

page_text: high-pressure steam, could it in the same way be packed up and made portable.
But as the air is compressed to a much higher density, and consequently has a
greater expansive power than the high-pressure steam as generally used, it is to
be expanded on an improved plan, as hereafter mentioned, so as to work out the
whole of the mechanical power. Suppose the air was charged with power equal
to forty atmospheres, then the best way appears, both for fixed machinery and
locomotive machines, is to wiredraw the air (as it is called when applied to
steam) down to about eight or nine atmospheres, and then to expand it in two
or more cylinders down to atmospheric pressure, so that no air with unexhausted
power may be thrown away, the operation of expansion being precisely the
reverse of compression. The preceding tables of compression will shew, by
reversing the pumps, the rules for expanding the fluid. Suppose air was to be
expanded from nine atmospheres down to atmospheric pressure in two cylinders,
and the piston of each cylinder was required to give precisely the same propel-
ling power to the machine, then the area of the second cylinder must be three
times that of the first, and their must also be a small reservoir to receive the
air when expanded in the first or smaller cylinder, and convey it to the second
or larger one precisely in the way that, in the progress of compression as before
mentioned, it takes it from the larger and carries it to the smaller one, then,
by letting the air into the small cylinder equal to about nine atmospheres, and
cutting of the supply at a third of the stroke, it will be expanded therein to
three times its previous bulk, and be thereby reduced in density from nine to
three atmospheres; it will then go into the small reservoir, and from that to the
second cylinder at the diminished density; but as that cylinder has an area of
three times that of the first, it will give the same mechanical pressure when
the air is as three as the other gave when at nine atmospheres, and by the
supply in that cylinder being also cut off at one third of the stroke the
air will be expanded therein to three times its previous bulk, and thereby
reduced in density down to atmospheric pressure, and consequently the whole
of the mechanical power first given thereto by the steam engines or other
machines will be completely extracted therefrom; when it is required to be
expanded down from sixteen atmospheres to atmospheric pressure in two
cylinders, the piston of each cylinder giving the same propelling power, then,
by the second cylinder being four times the area of the first, and the supply in
ench being cut off at the fourth of the stroke, that object will be obtained.
When power and motion is to be communicated to fixed machinery, situate at
a distance from the place where the steam, wind, water, or other mechanical
power is generated, then it may be done by compressing the air by any of the
before-mentioned machines into portable reservoirs, and conveying it to the

page_text: -place where power is wanted, in the same way that portable gas_is_now.con-
veyed where light is wanted. By this means very cheap power may be
supplied for various mechanical uses, such as turning cutlers' grindstones,
drawing wire, working cranes, cutting ornamental glass, working hydraulic
presses, turning all kinds of lathes, and many other similar purposes where less
than the power of a small steam engine is required, and which power is now.
frequently done by manual labour at a cost of at least twelve times the expence
of steam, wind, or water power. The power generated at the various tread-
mills might in this way be usefully employed.
Another way of conveying mechanical power generated and concentrated
in the ways before mentioned is through metallic pipes, also the same as gas;
then those mechanics and artisans in a manufacturing town who cannot afford
to have a steam engine of their own might be supplied with power in the same
way that those who cannot afford to have a gas apparatus of their own are
now supplied with light. In this way one steam engine might be made. to
work all the cranes-in any of the docks of London or Liverpool, similar to the
way recently proposed by Mr. Hague to work the cranes in the Saint Catherine
Docks by means of a vacuum. When power and motion is to be communicated
to projectiles, or rather when power is to be communicated to the gun and motion
to the shot, then the air should be comprised to a density that will give it an
elastic force equal to gunpowder, or if used at a lower density, then a larger
quantity must be used at each discharge, as is done with gunpowder. when of
inferior quality. The power may then be packed into and conveyed in. port-
àble reservoirs, as before mentioned. In many cases, that of fortified towns,
for instance, may be generated and compressed by one or more steam engines
placed in bomb proof works or covered ways, from whence a small pipe would
convey it round the ramparts and supply all the ordnance in the batteries.
The unobstructed speed of air at those high densities is supposed to be about
six thousand feet per second; but suppose it to pass through a small pipe at
the reduced speed of only two thousand feet per second, then a pipe of half
an inch area. would convey upwards of four hundred cubic feet of the com-
pressed air per minute, each cubic foot containing a quantity of power equal
to about seventy-two pounds weight of gunpowder. When this method of
giving a projectile force is used the ordnance will not require to be of so great
weight as at present, because there will not be equal danger of its bursting,.
and as air at less than one fourth of that density has more than twice the
speed of any projectile hitherto thrown, should it be made equally effectual as
gunpowder when at one fourth of the density, by using four times the quan-
tity for each change, then the gun at all events need be only one fourth of.

page_text: the usual weight. There must of course be a chamber to contain the com-
pressed air seperate from the shot, and this chamber must be refilled after
each discharge, and not be supplied with several charges, each diminishing in
force like the common air gun. An aperture the size of a common quill will
supply a charge of power equal to twenty pounds weight of gunpowder in one
second of time; the valve between the compressed air and the shot, which
is to be opened instantaneously to permit the air to act on the shot, must be
of the same area as the gun, or as nearly so as possible, for otherwise the
speed of the air would be retarded, and the required velocity not given to the
shot. Suppose, for instance, such valve was only one fourth of the area of
the gun, and supposing the unobstructed speed of the fluid was four thousand
feet per second, then it would pass through that small valve at a speed of only
one thousand feet per second, and therefore would not give the required speed
to the shot of nearly two thousand feet per second; and although the dis-
charge would appear to be instantaneous, it would not be so in reality, for in
one case a volume of one foot in length would pass through the large valve
in the one four thousandth part of a second, but in passing the small valve it
would be four times as long; that is, it would require a space of time equal
to one thousandth part of a second of time to pass through, which would not
be speed sufficient at all times and for all purposes. These directions and
observations apply to all kind of arms, from the pistol or fowling-piece to
the cannon or mortar. The chamber that is to contain the compressed air
may be increased or diminished in its capacity by making the breech to screw
in and out, whereby the engineer may increase or diminish the charge. The
elastic force of the air may be found to a single atmosphere in several ways.
One very simple way is to ascertain the capacity and weight of the reservoir
when empty, then the weight when charged will correctly furnish the density
of the fluid. When power and motion is to be communicated to carriages
and other locomotive machines travelling on land, then a number of reser-
voirs are to be placed and fixed under such machines, which are to be
charged with air compressed from thirty to sixty atmospheres; but a
sufficient quantity may be carried to propel such machines, with the pas-
sengers and luggage, from fifteen to twenty miles. When the density is not
higher than thirty atmospheres, locomotive carriages on railways, where the
draft required is so much less, and the space for containing the reservoirs is
so much greater, can easily carry sufficient power to enable them to draw
twenty tons weight one hundred miles, if necessary, before a fresh supply would
be required. The condensed air is to be wiredrawn; as before mentioned,
from the higher pressures of thirty or more atmospheres down to a convenient

page_text: working pressure, say, to eight or nine atmospheres, which is done by tlie
conductor of the machine partially opening a cock or valve through which
the fluid is admitted to the working cylinders, and by which he will regulate
the speed of the carriage, and when ascending hills or passing over bad or
new-made roads, then, by further opening those valves or cocks, a propelling
power of ten or twenty horses will be given, by which means the conducter
will obtain that additional power which the coachman now obtains by the use
of his whip; and that he may always have such additional power at command,
two, three, or more reservoirs should be kept charged at the full density; and
connected with the working cylinder-by-another-supply-pipe,-from-which,-by-
turning another cock, such additional power may be drawn, when the density
of the air in the other reservoir is reduced so as to be incapable of giving
the required additional power. The quanty of propelling power communicated
to and contained in a cubic inch of air, when subject to a mechanical pressure
equal to thirty-two atmospheres, is equal to the power required to lift one
hundred. and fifty pounds weight one foot high, and when subjected to a pres-
sure equal to sixty-four atmospheres then its elastic force is equal to the power
required to lift three hundred and sixty pounds weight one foot high; yet,
although a cubic inch under a pressure of sixty-four contains more power than
two cubic inches under a pressure of thirty-two atmospheres, it cannot conve-
niently be made to furnish much. more propelling power; because,.notwith-
standing one cubic inch under a pressure of sixty-four atmospheres will expand.
to and produce eight cubic inches at eight. atmospheres, yet one cubic inch at
sixty-four atmospheres possesses one sixth more power than two cubic inches
at thirty-two, and twice the power of eight cubic inches at eight atmospheres;
consequently, when wiredrawn from a higher to a lower density in the way
proposed, it will lose in the working, cylinder some part of its elastic force.
The above estimate of the elastic force of air under those pressures, if not
mathematically correct, is sufficiently so for all practicable.purposes. The con-
necting and service pipes between the reservoirs and working cylinders may
be made of the flexible pipes manufactured with india-rubber, which, when of
small area, may be made to bear a pressure of a thousand atmospheres. The
compressed air is to be expanded in the working cylinders, as before mentioned,
precisely the same way as steam in high-pressure-steam engines; and when
used for locomotive purposes the machinery then to be used for propelling
them is in every-respect-similar to that for the locomotive steam engines; but
as the air is proposed to be employed in the working cylinders at a density of
about eight or nine atmospheres, the piston and cylinders must be-propor-
tionably smaller to do the same work than those used for steam, at a lower

page_text: pressure; and when it is expanded in two cylinders, varying in their areas in
the proportions as before mentioned, the power obtained from each piston will
be precisely the same, consequently the smaller piston and cylinder may be
used for propelling one wheel, and the larger one the other. For locomotive
machines that do not travel more than from ten to fifteen miles from London
a steam engine erected anywhere on the line of road will supply several
machines with all the power required; but when a long line of road is to be
travelled then steam engines must be erected at certain stations from which
the reservoirs are to be supplied; for although wind or water mills would
furnish such power, yet the supply from them would not be sufficiently regular
to be depended on; but the best way to supply a long line of road will be by
pipes similar to those used to convey gas. Suppose, for instance, the coaches
in the line from Newcastle to London were to be propelled in this way, then
the steam power might be generated from the waste coals produced at the
mines in that neighbourhood, and the whole line of road from thence to Lon-
don might be supplied with condensed air for any number of coaches. Atmo-
spheric air, when under much less pressure than thirty atmospheres, is estimated
to travel from three to four thousand feet per second, but when taken at only
two thousand feet per second it will reach London in about twelve minutes,
and a pipe of only two inches in diameter would deliver two thousand four
hundred cubic feet per minute; and when the air is under a pressure of thirty
atmospheres, of which pressure the expansive force of a cubic inch is equal to
the power required to lift one hundred and thirty-eight pounds one foot high,
then two thousand five hundred cubic feet per minute would supply a quantity
of mechanical power equal to the continual labour of thirteen thousand horses.
These statements and calculations are given with less reluctance, because they
are merely school-boy questions, and easily corrected if erroneous; but whether
sent by pipes or supplied from steam engines stationed at every fifteen, twenty,
or twenty-five miles, the reservoirs must be made of a number of the smaller
ones connected together by pipes, and the number must be sufficient to form
one large reservoir equal to four or five times the quantity required to charge
each locomotive machine, then that reservoir being kept charged with air at a
density of from thirty-five to forty atmospheres will contain sufficient to charge
the reservoirs of the machines with the air at thirty atmospheres, or, as before
mentioned, the reservoirs of the locomotive carriages might be charged directly
from the pipes, as a branch pipe a quarter of an inch in area would supply one
hundred cubic feet in about thirty seconds. When power and motion is to be
communicated to ships, vessels, and other floating bodies, the reservoirs are to

page_text: be placed in the hold, which would conveniently contain a sufficient-number-of
them, when charged with air at a density of about thirty atmospheres to furnish
power for a short voyage of ten or twelve hours., Vessels that navigate or
depart from and return to navigable rivers may obtain the necessary supply of
power, by, one or more barges, with, two or three; pair of paddle-wheels-in
each, being moored.in such rivers, when those paddle wheels would-be put into
action by the influx and reflux of the tide, or the descending stream, if above
the influence of the tide, and thereby work the condensing pumps and com-.
-press the air at a very-moderate expense. The post office: packets and other
passage, vessels, making short voyages, when propelled in this way, would' have
some material advantages over, steam; they would be rid of the heat and
smoke, and all danger of being set on fire by the furnace, and the bouyancy
of the reservoirs would prevent their sinking evening if filled-with-water, as
each reservoir made to contain four. cubic feet of air at the density of thirty
atmospheres, weights about eighty pounds, and four cubic feet of air at that
density, weight nine pounds, making together eighty-nine, say, ninety pounds,
when, by their occupying the space of four cubic feet of water weighing two
hundred and fifty pounds, they, will each furnish a clear buoyant power of one
hundred and sixty pounds. Power might be supplied-for-a-much-longer time.by
making the most of the means of stowage, and increasing the density of the
air, but then the advantages to be obtained from the buoyancy of the reser
voirs would be lost, for the air would increase in weight in proportion to the
density, and the reservoirs must be made proportionally stronger, so that they
would soon become, heavier than water, bulk for bulk. This is an object of
some importance when it is considered how many persons are continually-pass-
ing between England and Ireland, and, England, and France. The working
cylinders, in which the air is to be expanded to give motion to the paddle
wheels of the vessel, will not require to be one tenth of the size of those used.
in steam vessels for low-pressure steam, which work with a pressure of about
ten pounds on the inch, when those with air will work with a pressure of
about one hundred and twenty pounds on the inch, when wiredrawn to eight
or nine atmospheres..
I have not herein particularly described the mechanism of the air gun or the
locomotive machines, although my discovery and improvements have-reference
thereto by supplying them with power, because they are well known; but I
have fully described my improved machinery for compressing atmospheric air,
whereby that fluid is made a useful assistant in forming a depository and
vehicle of mechanical power; and this Patent is intended to secure the appli-