Instruments for Measuring, Indicating, and Regulating the Pressure and Temperature of Air, Steam, and other Fluids, and for Obtaining from them Motive Power.
Year: 1849

page_text: Instruments for Measuring, Indicating, and Regulating
the Pressure and Temperature of Air, Steam, and
other Fluids, and for Obtaining from them Motive
Power.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
COWPER, of Southampton Buildings, Chancery Lane, in the County of Middle-
sex, Patent Agent, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Fifteenth day of
December (One thousand eight hundred and forty-nine), in the thirteenth
year of Her reign, did, for Herself, Her heirs and successors, give and grant
unte me, the said Charles Cowper, my exors, adiñors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Charles Cow-
per, my exors, adñors, and assigns, or such others as I, the said Charles
Cowper, my exors, adiñiors, or 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 make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, in the Islands of
Guernsey, Jersey, Alderney, Sark, and Man, and in all Her Majesty's Colonies
and Plantations abroad, the Invention of "IMPROVEMENTS IN INSTRUMENTS FOR
MEASURING, INDICATING, AND REGULATING THE PRESSURE OF AIR, STEAM, AND OTHER
FLUIDS, AND IN INSTRUMENTS FOR MEASURING, INDICATING, AND REGULATING THE
TEMPERATURE OF THE SAME, AND IN INSTRUMENTS FOR OBTAINING MOTIVE POWER
FROM THE SAME," communicated to me from abroad; in which said Letters
Patent is contained a proviso that I, the said Charles Cowper, shall cause a

page_text: particular description of the nature of the said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand
and seal, to be inrolled in Her Majesty's High Court of Chancery within
six calendar months next and immediately after the date of the said in part
recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Charles Cowper, do hereby declare the nature of the said Invention, and the
manner in which the same is to be performed, are fully described and ascer-
tained in and by the following description thereof, reference being had to the
Drawings hereunto annexed, and to the figures and letters marked thereon,
that is to say :-
The Invention relates to the construction of instruments for measuring,
indicating, and regulating pressure and temperature, and for obtaining motive
power, by means of tubes of metal or other suitable material arranged in
various forms, and in some of which a vacuum is formed, whilst in other
arrangements air, steam, water, or other fluids are introduced. The form and
section of the tubes are such as to cause them to undergo a change in their
form when they are submitted to internal or external pressure. For this pur-
I employ tubes whose transverse section is of any form other than a
circle, and I distort the form of these tubes by bending or twisting them.
The effect of internal pressure on these tubes tends to cause them to approxi-
mate to the circular form of section, and in so doing to straighten the bent
tubes, and to untwist the twisted tubes.
pose
Sheet 1, Figure 1, represents a thin brass or copper tube of the section
shewn in Figure 1, A, and which has been bent, as shewn in Figure 1, with
its flat side towards the interior of the curve. This tube is open at the
extremity a, and closed at the other extremity, which carries an index b. If
steam from a boiler be now admitted to the interior of the tube at a, so as to
increase the pressure in the tube, the consequence is, that the flat side of the
tube is caused to bulge slightly, and the effect of this bulging is to cause
the curvature of the tube to open itself, thus carrying the index b from
the point a.
The amount of this motion varies with the pressure of the-steam,
so that, by applying a properly graduated scale behind the index, a pressure
gauge is at once obtained. If a partial vacuum be formed in the tube, its
curvature is increased, and the index then moves in the opposite direction or
towards the end a. It thus serves as a vacuum gauge as well as a pressure
gauge. The same effects are produced if the flat side of the tube is placed on
the exterior instead of on the interior of the curve, and the amount of the
away

page_text: motion is increased by making both sides of the tube of a flattened or partially
flattened form. The principle of the Invention is still farther exemplified by
Figure 19, in which A represents a flattened tube bent into a circular form,
and shewn in section at B. If we suppose this tube to be submitted to
internal pressure, whilst the ends are prevented from moving, the tendency of
the pressure is to bulge the flat sido; but in so doing it would be forced into
a smaller diameter, and consequently the metal would become cockled, as
shewn in the Drawing. If, however, the ends of the tube are free to move,
they will separate from one another, and thus relieve the inner side of the tube.
If the outer side of the tube is also capable of bulging, it will be forced out
to a larger diameter, and will also tend to open or straighten the curvature of
the tube.
The Figures 2 to 12 inclusive represent some of the infinite variety of sec-
tional forms which may be employed for the purposes of the Invention. These
tubes may be made of brass or copper, either by flattening cylindrical tubes,
or by drawing the tubes at once of the required form, or by stamping
or rolling separate pieces of metal, and soldering them together, as in
Figure 12, or they may be made of iron or steel, glass, caoutchouc or gutta
percha, or of any other suitable material, according to the purposes for which
they are intended. When the tubes are intended to be used as exact
measures of pressure, they should be formed of materials as elastic as possible,
as the tube acts nearly in the same manner as the spring of an ordinary
spring balance in bringing back the index to its starting point as soon as the
pressure ceases. These tubes may be bent in an infinite variety of forms,
some of which are shewn in the Figures 18 to 19 inclusive. They may also
be twisted in different manners and in various degrees, as shewn, for example,
in elevation and plan in Figures 20, 21, and 22. The tube may be fixed at
one end, and moveable at the other, as in Figures 1; 14, and 16, or it may be
fixed in the middle, as at c, in Figure 18, and then both branches will be
moveable. The index 6 may be either attached directly to the moveable end
of the tube, as in Figure 1, or connected with it indirectly by means of levers,
as in Figure 18, or by toothed wheels or sectors, or by a silk thread, or in
any other convenient manner. Figure 23 shews an elevation, and Figure 24
a plan of a method of connecting the index with the tube. The pin G is.
firmly fixed to the end of the bent tube, and carries an arm B, to the extremity
of which is attached a thread of silk, hair, or metal C, or a small chain which
is wound round the spindle A', and its end attached to the spring H, which is
fixed to the support E on the plate D. Another arrangement is to attach to
the spindle itself a spiral spring, or a helical spring like that shewn at H in
b

page_text: Figure 25, in which the same letters refer to similar parts to those in Figures
23 and 24. The tubes may be fixed in various ways, as, for instance, by
soldering, or by a union joint; as in Figure 26, or by driving a ferule outside
or inside the tube; as shown in Figures 27 and 28. In these Figures the
connecting piece T, to which the tube is fixed, serves for connecting it to the
steam boiler or other vessel, the pressure in which it is required to ascertain.
In Sheets 2, 3, and 4 of the Drawings hereunto annexed are shewn various
applications and combinations of tubes adapted for pressure gauges, baro-
meters, thermometers, and indicators, and for obtaining motive power and
other purposes.
Figure 29 is a pressure gauge consisting of a tube A, similar to that shewn
in Sheet 1, Figure 1. This tube is fixed at one end to the connecting piece T,
which carries a stopcock which communicates with a steam boiler, the pressure
of steam in which is to be ascertained. The other end of the tube is connected
by a joint or by a thin flat steel spring to the long index b, which is supported.
at the bottom by another thin flat spring d, which serves as a joint or hinge
for it. The motion of the index over the graduated arc G shews the amount
of the pressure in the boiler. The arc G is graduated, in the first instance,
by comparing the instrument at various pressures with an accurate mercurial
or other pressure gauge, and it will be found that for equal increments of
pressure the spaces moved over by the index are equal, or nearly so. The
instrument is enclosed in a, box of wood or metal with a glass front to protect
it from injury. Figures 30 and 31 représent an instrument formed of several
similar tubes united together, fixed at one end a, and carrying at the other
the index b, to shew the motion of the tube. Figure 32 represents another
arrangement analogous to that shown in Figure 17, Sheet 1, and also serving
as a pressure guage, and so arranged that the index moves in a straight line.
The successive branches A, B, C, are formed by bending backwards and for-
wards a single tube, which reaches from the point a to the junction of the
index D at f. The branches being symmetrical, and all in the same plane,
the motion of the index takes place in a straight line. on the scale E.
Figures 33 and 34, Sheet 3, represent other forms of pressure gauges in which
the notion of the index is increased by means of. levers, and the whole instru-
ment is enclosed in a circular box. Figure 35 is another variation of form, in
which a circular tube A is fixed at one end to the connecting piece T, and at
the other to a lever L, which is connected by a short link c to the lever m, the
axis of which carries the index D. The instrument may of course be arranged
in an infinite variety of forms. Thus, Figure 26 shews a circular tube A con-
nected to a toothed sector H, which works into a pinion p on the axis of the

page_text: index D. Figure 37 shews a similar arrangement, in which the axis of the
index is in the centre of the box, so that the graduated scale is concentric
with the box. In Figuro 38 the index is concentric with the box, as in
Figure 37; but the tube-is fixed in the centre at c, and the two ends a and a¹
are connected by links n to the lever o, on the axis of which is fixed the toothed
sector H working into the pinion p on the axis of the index D. This arrange-
ment has the advantage of balancing the two branches of the tube, so as to
admit of placing the instrument in various positions without altering its indica-
tions. The toothed sector H is balanced by a small weight on the opposite side
of its axis, and which is not represented in the Drawing.
Figure 39 represents an elevation and section of an instrument consisting
of a tube bent into a circular or helical form of a greater or less number of
convolutions, according to the amount of motion required in the index. This
instrument is inclosed in an oval box, and has the advantage of great sim-
plicity, and of not requiring any wheelwork or other mechanism for trans-
mitting the motion to the index. In this instrument I have shewn two little
sliders 7, 1, which are pushed along by the index in its course, and serve to
register the maximum and minimum pressure. D' is a second index which
may also be used in a similar manner for registering the maximum or mini-
mum pressure. The index D¹ can be moved by a button on its axis. This
button, or the glass which covers the index, is secured by a lock p. The
instrument thus arranged and applied to a steam boiler serves as an excellent
check upon the stoker, as it can be at once ascertained, by inspection, what
are the highest and lowest pressures at which the boiler has been working
since the last adjustment of the sliders 1, 1. The instrument is also an excel-
lent guide to the stoker in indicating to him whether the pressure is rising or
falling. Pressure gauges constructed on the principles above described may
be conveniently applied in some cases for ascertaining the level of the water
in a reservoir at a distance. Thus, if a steam engine is being used to raise
water into a reservoir at a considerable distance, it is desirable that the engine
driver should be able to ascertain when the reservoir is full. For this purpose
one of the improved pressure gauges. is connected to the pipe through which
the water is forced, and the engine driver occasionally stops the engine, and
allows the water in the pipe to become quiescent. He then turns a cock
which admits the water to the pressure gauge, which shews the height of the
water in the reservoir at once.
I have described the above instruments as being employed as pressure
gauges, and it is evident that they may be employed for ascertaining the
pressure of steam, air, gas, water, and fluids in general. These instruments

page_text: are, however, capable of several different applications. Thus, by connecting
the interior to a steam boiler or any vessel, the pressure in which is to be
ascertained, the instrument serves as a pressure gauge, as already described.
If there is a partial vacuum in the vessel, the index will move in the opposite
direction, and the instrument then serves as a vacuum gauge. By filling the
tube with any liquid, such as mercury or alcohol, and closing it hermetically,.
the expansion and contraction of the liquid, by variations of temperature, pro-
duce a pressure upon the sides of the tube, and the motion of the index over
a suitably graduated scale will then indicate the degrees of temperature. The
instrument thus serves as a thermometer. If a vacuum is made in the tube,
by withdrawing the air by means of an air pump or otherwise, and it is then
closed hermetically, the atmospheric pressure acting on the exterior of the tube
will move the index until the pressure of the atmosphere is in equilibrium
with the elasticity of the tube. As the atmospheric pressure varies, the index
will indicate the variation on a scale previously graduated by comparison with
a standard barometer.
Figure 40, Sheet 3, represents a back view and a section of a barometer
formed of a flattened tube bent into a spiral, and connected to an inverted
index. B is the spiral tube fixed at one end to the back of the dial C, and
carrying at the other end an arm D, connected by a link E to the index F.
A vacuum is formed in the tube B, which is then hermetically closed by
soldering or otherwise.
Figure 41 is another form of barometer, the index F being concentric with
the box. B is the tube in which a vacuum is formed. Figure 42 is another
form in which the tube B is a spiral of two turns, and is fixed at the end a,
and jointed at the other end to the lever m, on the axis of the index F.
Figure 43 is another form of barometer. B, B, are two spiral tubes from
which the air has been withdrawn, and which are connected by the links n, n,
with the lever o, on the axis of the index F. This arrangement has the advan-
tage of balancing the tubes, so as to admit of the instrument being placed in
various positions without altering its indications. The dimensions of these
instruments may evidently be varied at pleasure, and a barometer and thermo-
meter, each constructed on the above-described principles, may be placed in
the same box, and their indications may be shown on the same dial.
Sheet 2, Figure 44, represents a back view and a section of a barometer
made with a twisted tube of a flattened section, like one of those shewn in
Sheet 1. A is the twisted tube inclosed in an oval box, and soldered at its
lower end to a piece of brass a, which serves to fix it to the box. At its upper
end it carries a pivot which turns in the support b, also fixed to the box.. A

page_text: lever B, fixed to this end of the tube, is connected by a link to a shorter
lever E, turning upon the axis C, and carrying a toothed sector, D, working
into the endless screw G on the axis of the index I. The motion of the index
is thus much greater than that of the tube. The air having been withdrawn
from the twisted tube A, it will be found to twist and untwist itself slightly
with the variations in the pressure of the atmosphere, and to produce corre-
sponding motions in the index.
Figure 45 represents the back view of another form of barometer with a
twisted tube A, which may conveniently be made of considerable length, so as
to have a considerable motion in the free end which carries the toothed sector
D, working into an endless screw on the axis of the index, as shewn at the
foot of Figure 45.
Figure 46 is a barometor, and Figure 47 a pressure gauge, both made in a
similar manner, with the index I attached at once to the end of the twisted
tube A, which is exhausted of air, and closed hermetically for the barometer
Figure 46, but is connected to a stopcock in the pressure gauge, Figure 47.
It is surrounded with a sheath to protect it. In the centre of the glass which
covers the dial is a button b, attached to the axis of a second index I', which
is capable of turning with very little friction. The index I carries a. little
pin c, by which it is pushed along by the index I, and is left by it at the
extreme point of its course, thus serving to register the maximum pressure.
A third needle, 12, arranged so as to move independently of the other, may be
added, as in Figure 47, to register the minimum pressure, or two little sliders
may be used as in Figure 39, Sheet 3, being fitted on a little arc of metal or
in a groove. These sliders will be pushed each way to the extreme range of
the index, and will remain there registering the maximum and minimum.
This arrangement may of course be applied to all the various forms of the
pressure gauges, barometers, and thermometers. If one of the barometers be
immersed in water, it is evident that the pressure of the water will act upon
it in the same manner as an increased pressure of air, and the greater the
depth to which it is immersed, the greater will be the motion of the index.
In this way a gauge for the depth of water is obtained which may be used in
place of a lead for. taking soundings. For a deep sea lead the tube should
of course be made thicker and stronger than is required for a barometer.
The little slider will indicate the maximum pressure to which the instrument
has been subjected, and will thus show the depth to which it has descended.
Figure 48 is a similar instrument to Figure 46, excepting that the dial is
semicircular, and the end of the index is bent upwards, so as to work round

page_text: the outer circumference of the dial. This form can be conveniently fixed
against a wall.
Figure 53, Sheet 3, is a pressure gauge in which the tube A is bent into a
helical form of several turns, and connected to the arm D on the axis of the
index b.
Figure 49, Sheet 2, is a vertical floating thermometer, having a hollow
vessel c below the graduated dial to serve as a float to support the instrument
at the surface of the liquid in which it is immersed. The sheath is replaced
by two parallel rods t, so that the tube A' may be in immediate contact with
the liquid. The tube may be of copper, brass, silver, platinum, glass, or other
material, according to the nature of the liquid into which it is to be immersed.
Various liquids may be employed to fill the tube, but in most cases alcohol
will be found the most convenient. The motion of the index may. be
multiplied by levers or otherwise. This new thermometer is very convenient
for observation, as the motion of the index may be seen without the necessity
of removing the instrument from the liquid. It is not fragile like the ordinary
thermometers, and can be fitted with maximum and minimum sliders, so that
besides its ordinary applications it may be used with advantage to ascertain'
the temperature of the sea at considerable depths, for which purpose, of
course, the float would be removed, and a weight attached to sink it.
The improved instruments may be applied to other purposes besides those of
measuring and indicating pressure and temperature..
b
This Figure, 50, represents a vertical section of an instrument in which a
twisted tube is applied to regulate pressure, and which may be used to regulate
the pressure of gas, water, or other fluids contained in reservoirs, in which the
pressure is variable. A is a reservoir or cylinder supposed to be filled with com-
pressed gas;
B is a piece of metal screwed into the cylinder, and surmounted
by the stopcock C; D is a tube or sheath containing the twisted tube E; a is a
conical valve loosely fitted on the stem of the screw b; c is a stuffing box
packed with leather, through which the stem of the screw 6 passes; d is a little
tube connected at bottom with the twisted tube E, and at top with the little
chamber f, which is connected by another passage e with the reservoir A.
Another passage 9 leads from the chamber f to the cock C. The action of the
apparatus is as follows:-The cylinder A being full of compressed gas, if the
cock C is opened the gas will begin to escape, passing through the passage e into
the chamber f, and by the passage g to the cock C, and at the same time a portion
gas will pass down the pipe d, and exert its pressure on the interior of the
tube E, the exterior of which is only exposed to the ordinary pressure of the
of

page_text: atmosphere, which has free entrance to the sheath through a small hole at the
upper part made for that purpose. The pressure acting on the tube E causes it
to untwist, and in so doing it turns the screw b, and closes the valve a until
the pressure comes into equilibrium with the elasticity of the tube; the
valve a then keeps the orifice of the passage e sufficiently open to supply
a steady current of gas, the quantity depending on the degree of opening of
the cock C. As the pressure in the reservoir diminishes the valve will open
more and more, accommodating the size of the opening to the diminished
pressure, so that the pressure in the chamber fremains nearly constant until
all the gas is expended. It is evident that the improved thermometers may be
applied to regulate temperature in a similar manner by causing the tube to
act upon a valve in a steam pipe or a damper in a flue, or otherwise, according
to the source of heat. They may also be connected to a ventilating valve so
as to admit fresh air into an apartment, or to allow of the escape of heated air
when the temperature rises above any determinate degree. A pressure gauge
may also be applied to a steam boiler, and arranged so as to close and open the
damper as the pressure of the steam rises and falls. It may also be made to
sound a whistle or bell, or other alarm, when-the pressure rises above a certain
point.
Figure 51 shows an application of the Invention for the purpose of
obtaining motive power from the variations in the temperature and pressure
of the atmosphere, and which power may be applied to winding up clocks and
other purposes. This apparatus consists of two flattened tubes A bent into a
spiral form, and fixed at one end to the box, and at the other end connected by
two connecting rods B to the bent lever C, on the long arm of which is
a toothed sector working into the pinion D, which turns loose upon its spindle,
and is provided with a pall, which takes into the ratchet wheel E fixed on the
spindle. This ratchet wheel is provided with another pall F, which prevents it
from turning backwards. The action of this apparatus is as follows:-The
two tubes A, A, are exhausted of air, and a small quantity of ether, or some
other very volatile liquid is introduced, a portion of which becomes converted
into vapour, and fills the interior of the tubes. The vapour of ether being
very susceptible to changes of temperature, naturally produces variations of
pressure in the interior of the tubes whenever even a very slight change takes
place in the temperature or pressure of the atmosphere; the consequence
is, that the curvature of the tubes opens and closes itself day and night
on account of the almost regular change of temperature which takes place.
This motion being multiplied by the levers and gearing turns the pinion D,
the axis of which being prolonged to the wheelwork of the clock, winds up the

page_text: weight or spring more or less in proportion to the variations in the tem-
perature. By this means clocks and other machinery fitted with this appa-
ratus will not require to be wound up by hand, as the apparatus will wind them
up every day. As a still farther explanation of the principle of this apparatus,
I have shewn in Figure 52, Sheet 2, an elevation and a partial section of an
apparatus, which may be called a thermometric and atmospheric remontoir.
It consists of a glass cylinder A containing mercury, and terminating in a
tube, the open end of which is immersed in mercury contained in the vessel B.
The cylinder A is suspended by a cord c attached to a wheel C, which turns
on the axis a. A weight D is attached to the wheel C to balance the weight
of the cylinder A, and the mercury contained in it. A ratchet wheel E turns
loosely on the axis a, and carries a barrel F, upon which is wound the cord
which supports the weight to be raised. A pall attached to the wheel C takes
into the teeth of the ratchet, and another pall attached to the framing prevents
the ratchet from turning backwards. The apparatus acts in the following
manner: A small quantity of ether is introduced into the glass cylinder A; the
vapour of which fills the otherwise empty space above the mercury. This
vapour expanding and condensing by the variations in the temperature and
pressure of the atmosphere drives out or draws in the mercury in the cylinder,
and. thus alternately renders the apparatus lighter or heavier. When it
becomes lighter it rises a little, being raised by the balance weight D, and the
pall passes back over some of the teeth of the ratchet. When the cylinder
preponderates again it descends; raising the weight D, and pushing the ratchet
wheel round, raises the weight which is suspended to the barrel F. It will
readily be understood that the power thus obtained from the diurnal variations
of temperature and pressure may be applied to wind up a weight or spring,
the action of which may continue until the next variation of temperature
or pressure again winds it up. It will be also easily perceived that the appli-
cation of twisted or bent tubes to this purpose, as in Figure 51, avoids the
inconvenience and expense of employing a large quantity of mercury, whilst at
the same time that apparatus may be placed in any position, and the power
easily be increased by employing larger or longer tubes, and increasing their
number. A large number of twisted tubes, for instance, may be placed side
by side, and the powers of all them combined by levers or wheelwork so as to
act upon the same wheel or spindle.
Figure 54 represents a section, and Figure 55, a plan of a steam engine
indicator. This instrument differs from the ordinary indicators in being
constructed with a twisted flattened tube in place of the cylinder and piston
and spring which are ordinarily employed for moving the pencil. The con-

page_text: struction in other respects is easily understood. The cock E being connected
to the top or bottom of the steam engine cylinder, the steam enters by the
little tube F into the twisted tube D, inclosed in a sheath C; a to and fro
.motion is thus communicated to the arm G, which carries the pencil c, and
this motion is in proportion to the pressure of the steam. A, A', are cylinders
on which the paper is wound.; B is a framing by which the cylinders are sup-
ported. The pulley H is fitted on the axis of one of the cylinders A', and can
be fixed in any position by means of a set screw a. A second pulley I has
attached to it a string which is connected to the beam or cross head of
the engine. On the axis of the pulley I is wound a string, the other end of
which is attached to the circumference of the pulley H, and serves to reduce
the motion of the strip of paper to a convenient length. The cylinder A con-
tains. a spiral spring which keeps the paper and the strings properly stretched.
The paper thus receives a to and fro motion while the pencil travels across it,
as in the ordinary indicator, and the figures thus drawn have the advantage
of great exactness, as, the friction and the weight of the moving parts are much
less than in the ordinary indicators. There is no necessity of cleaning or
drying the interior of the apparatus, and the whole thing is lighter and more
portable than the ordinary indicators. As the pencil moves in an arc. of
a circle a curved scale of the same radius should be used in measuring the
figure. If it be wished to have the motion of the pencil in a straight line, it
may be effected by applying a parallel motion to it. It is evident that the
forms of the tubes employed for indicators may be varied like those employed
for the other instruments. Thus, Figure 56, Sheet 4, shews a front view
partly in section, and Figure 57 a side view with a part plan of another form
of indicator. The bent flattened tube F is attached to the connecting piece
and stopcock E, by which it is put in communication with the cylinder of the
steam engine. The other end of the bent tube is connected to the long arm G
turning on a pin at the bottom, and carrying the pencil c at the top, which
moves in an arc, varying but little from a straight line. The paper is placed
on a plate A instead of on a cylinder. Behind the plate A, is a rack d driven
by a small pinion, on the axis of which is a wheel e, on which is fitted the
pulley H; a string is wound on the pulley H, and connected with the piston
rod or some other part of the steam engine, so that a plate A, with the paper
upon it, moves up and down with the motion of the piston of the engine whilst
the pencil travels across it, with the variations in the pressure of the steam.
A spiral spring is contained in the wheel e to keep the string properly
stretched. The instrument may be still farther simplified by removing the
lever G, and attaching the pencil at once to the end of the tube.

page_text: Figures 58 and 59 represent another application of the Invention to the
construction of an engine to be worked by steam, air, water, or other fluid.
In this machine the cylinder and piston are replaced by a bent tube A, con-
structed on the same principle as the other instruments already described, and
acting on the crank E by means of a connecting rod. The tube A may be
made in various ways and of various materials. It is here supposed to be
formed of two sheets of steel rivetted or bolted together, as shown in Figure 59,
and firmly fixed to one end of the framework of the machine. D is an
excentric, the rod of which gives motion to a slide valve C working over two
ports, as in a single-acting engine. The tube A is filled with water, oil, or
other liquid up to the level of the port in the slide box. If steam from a
boiler be now admitted into the slide box it will press upon the surface of the
liquid, and will cause the curvature of the tube A to open, thus imparting
motion to the crank E and fly-wheel in the direction of the arrow. When the
crank has reached the end of its stroke the excentric will move the valve so as
to cut off the supply of steam, and open a communication between the tube A
and the external atmosphere or the condenser. The steam which has entered
the tube A will then escape, and the tube will return to its former position by
means of its own elasticity, which will be assisted by the pressure of the
atmosphere if a condenser be used in connection with the engine. The steam
will then again be admitted, and thus a continuous rotation of the fly-wheel
will be obtained. By this means engines may be made capable of working at
very high velocities and of great simplicity, and avoiding the loss of steam and
the friction of ordinary piston engines. It will be readily understood that
twisted tubes may be employed in place of the tube A, and that several tubes
may be combined together and regulated by the same or different valves, and
that the form of the tubes may be infinitely varied, as in all the other instru-
ments above described.
Figure 60 is a back view, and Figure 61 a section of a pressure gauge with
an illuminated dial, and which will be found convenient for steam vessels, and
in other cases where the instrument is to be seen at night. The scale is
painted in opaque colors on a semi-transparent dial D, such as ground glass,
porcelain, or horn, and a lamp G is placed behind it at night to render the
scale visible. The bent tube B is connected with the boiler by the cock J,
and its two branches are connected by links to a lever attached to the index C,
which is balanced on its axis. The index is thus not affected by the rolling of
the vessel. The index is adjusted to its proper position in the first instance,
and is secured to the lever by a small screw at e. Figures 70 and 71,
Sheet 8, shew two other methods of adjusting the index by means of a spring S

page_text: acting on the bent tube A. In Figure 70 the spring is adjusted by a small
nut e, whilst in Figure 71 the spring is of a V shape, and is adjusted by
a wedge e, advanced by the screw c. Sheet 4: Figures 62, 63, and 64 are
pressure gauges very similar to those already described, and are each provided
with a small set screw for adjusting the index. If it be required to adapt an
instrument to a scale already graduated, it may be done either by varying the
length of that part of the tube which is allowed to move, or by varying
the length of one of the levers. One mode of effecting this is shewn in
Sheet 3, in which Figure 66 is a plan, and Figure 67 an clevation.. A is the
spindle of the index, on which is fixed a cross bar B, carrying a bent piece of
brass C, to each end of which is fixed a steel pin D. The two links E, E, are
slipped on to the pins D, and connected at their other ends with the two
branches of the bent tube, like the links n, n, in Figure 38, Sheet 3. F is a
cross piece attached to the spindle A, and has two slots which receive the tops
of the pins D. The bottoms of these pins cuter two corresponding grooves in
the bar B. A screw G with a conical head is screwed into the bar B. By
screwing this screw down its conical head springs open the two branches of the
piece C, thus pushing the pins D farther from the centre and altering the
leverage. Figure 68 shews a plan, and Figure 69 an elevation of another
method of obtaining the same result. A is the spiudle; B, the cross bar or lever;
C, C, are two sliding blocks carrying the pins D, D, and adjusted by means of
the screws G, G. The links are connected to the pins D as in the preceding
arrangement: As in some cases the pressure gauges may become filled with
water, and may then be liable to be exposed to frost, I have shown at
Figure 65, Sheet 2, a means of preventing such an accident. Between the
instrument and the cock J, which puts it in communication with the boiler, is
placed a sort of flat box of brass or iron composed of two dishes C', C³, bolted
together round the circumference, and separated by a flexible diaphragm
of vulcanized india-rubber, or other sufficiently flexible material. The tube of
the pressure gauge and the part of the box in connection with it, which
in Figure 65 is the lower part, are filled with dilute alchohol, or some other
liquid which does not freeze at the temperature to which the instrument
is liable to be exposed. The plug E of the cock J is traversed by a holo
corresponding to the tube F', and has also a lateral hole a, by means of which
a communication can be opened with the atmosphere through the orifice 6 for
allowing of the escape of the water contained in the upper part of the box.
By this arrangement the water produced by the condensation of the steam in
the tube F', and in the upper part of the box C', is prevented from mixing with

page_text: the alcohol contained in the pressure gauge, which is separated from it by the
diaphragm. By turning the cock into the position shewn at the left of
Figure 65, a communication is opened from the upper part of the box C' to
the atmosphere. The tube of the pressure gauge now contracts itself, pushing
up the diaphragm and expelling the greater part of the water above it. All
that is necessary then is to turn the cock into the proper position whenever
the instrument is out of use. The application of this contrivance is shown in
Figure 47, Sheet 2, and in Figure 53, Sheet 3.
Figure 72, Sheet 8, is a pyrometer for measuring high temperatures. A is
a vessel of iron, platinum, or other metal filled with air, or with a gas which
has no action on the metal at the temperature to which it is to be exposed;
B is a tube of small internal diameter connecting the vessel A with one of the
improved pressure gauges C, which is filled with water or other liquid, and
separated from actual contact with the gas by a flexible diaphragm, as above
described in reference to Figure 65. When the vessel A is exposed to beat
the gas endeavors to expand, and in so doing exerts its. pressure upon
the pressure gauge C, the scale of which has been previously graduated by.
comparison with a mercurial thermometer up to 600°, and the divisions con-
tinued beyond that point as far as required, as in the ordinary way of gradu-
ating thermometers. Or the whole instrument may be filled with mercury or
other liquid, and employed for temperatures below the boiling point of the
liquid. I may observe, that for barometers of about four inches diameter it is
convenient to employ brass tubes of a thickness of about one hundredth part
of an inch, and of a section similar to Figure 3, Sheet 1, when the tubes are
drawn, or similar to Figure 12, when they are formed by soldering together
two curved strips of metal; but, as has been already stated, other materials,
forms, and dimensions may be employed. And.I do not confine myself to the
precise details so long as the peculiar character of the Invention be retained,
but I claim the construction for the purposes of the Invention of instruments
operating by the changes of form caused by variations of internal or external
pressure, however produced, in suitably arranged bent or twisted tubes, whose
transverse section is of a flattened form, or of any form differing from that of a
circle, as above described.
In witness whereof, I, the said Charles Cowper, have hereunto set my
Land and seal, this Fourteenth day of June, in the year of our Lord
One thousand eight hundred and fifty.
CHARLES (L.S.) COWPER.

page_text: AND BE IT REMEMBERED, that on the Fifteenth day of June, in the
year of our Lord 1850, the aforesaid Charles Cowper came before our said
Lady the Queen in Her Chancery, and acknowledged the Specification afore-
said, and all and every thing therein contained and specified, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Enrolled the Fifteenth day of June, in the year of our Lord One thousand
eight hundred and fifty.