IMPROVEMENTS IN TRACTION ENGINES, AND IN APPARATUS FOR INDICATING THE PRESSURE OF . ' STEAM
Year: 1862

page_text: SLETTERS PATENT to Andrew Barclay, of Kilmarnock, in the County of
Ayr, North Britain, Engineer, for the Invention of "IMPROVEMENTS IN
TRACTION ENGINES, AND IN APPARATUS FOR INDICATING THE PRESSURE OF
.
'
STEAM".
'
Sealed the 5th September 1862, and dated the 10th March 1862.
PROVISIONAL SPECIFICATION left by the said Andrew Barclay at the
Office of the Commissioners of Patents, with his Petition, on the 10th
March 1862.
CI, ANDREW BARCLAY, of Kilmarnock, in the County, of Ayr, North Britain,
5 Engineer, do hereby declare the nature of the said Invention for "IMPROVE
MENTS IN TRACTION ENGINES, AND, IN APPARATUS FOR INDICATING THE PRESSURE OF
STEAM," to be as follows, that is to say:-
0₁
This Invention relates, firstly, to the arrangement and construction of loco-
motive steam engines which are adapted for running on ordinary roads; and
are known as traction engines. Under one 'modification an ordinary tubular
locomotive boiler is arranged within a rectangular framing. The engine runs
upon two 'driving wheels of large diameter arranged towards the front end of
the engine, the backward end being supported by a single trailing wheel fitted
CD 021

page_text: in the centre of the framing beneath the foot plate. The pair of driving
wheels run loosely on the main axle, and each wheel is driven by a distinct
pair of engines arranged on the opposite sides of the framing. The main axle
extends sufficiently beyond the framing to admit of the cylinders of each pair
of engines and their connected parts arranged between the framing and the
inner faces of the driving wheels. The two cylinders on each side are bolted
to brackets projecting laterally from the framing, and they are placed in a
diagonal position, with their upper ends converging and directed towards the
driving shafts above. The upper end of the piston rod of each cylinder
traverses in a guide cast on the cylinder cover. The piston rods of each pair
of engines are connected to one oftwo crank shafts arranged above each shaft
giving motion to one of the driving wheels, and being quite distinct from its
fellow wheel. Extending upwards from the side pieces of the framing are two
standards, in the upper parts of which are fitted the bearings of the duplex
crank shanks. One pair of engines is coupled to one of the crank shafts on
one side of the framing, and the other on the opposite side, each having the
usual eccentrics for reversing the motion of the engines. On the opposite or
free extremity of each crank shaft is a pinion which gears into the teeth of an
aunular wheel formed on the inside of the rim of each driving wheel. The
rotatory movement imparted to each crank shaft causes the pinions to actuate
the driving wheels, and so propel the machine in either direction as desired,
The eccentrics of each pair of engines are actuated by a pair of hand levers
arranged one on each side of the fire-box, similar to the ordinary locomotive
engine, and connected to the eccentrics above by a suitable arrangement of a
central lever and connecting links. The guiding of the machine is preferred
to be effected solely by the steam being caused to check the speed of one
wheel while that of the other is increased; this is done by arranging the
regulator so that a simple motion of the handle towards. the side on which the
engine is desired to turn, will cause the steam to be partially shut off from
that pair of engines, and a larger quantity is admitted to the other pair; the
result is that the outside wheel moves with greater velocity than the inner,
and the engine is instantly turned to the right or left as desired by the
motion of the regulator handle in a corresponding direction, or vice versa. In
this way the engine driver whilst looking ahead is enabled to turn the engine
quickly in either direction without any other steering apparatus. The trailing
wheel or wheels may be arranged to turn to the right or left by means of a
screw if required. Another arrangement is to fit each of the driving wheels
to a tubular boss, running loosely on the main axle; to this boss is keyed a

page_text: spur wheel, which is driven by the pinion on the crank shaft. This modifi-
cation dispenses with the annular wheel on the inside rim of the driving wheel.
The duplex shafts may each be arranged with a coupling and gearing to
connect the shafts and reduce the speed in ascending inclines. It is preferred
to make the peripheries of the driving wheels with hexagonal or other
shaped recesses to receive wooden plugs, which are allowed to project a
little beyond the recess; as the wheel rests upon these wooden surfaces little
or no noise is made by the wheels in passing over paved roadways.
The second part of this Invention relates to the arrangement and con-
struction of a pressure gauge to be used with this and other engines. The
apparatus consists of a brass box forming a steam chamber, in the upper part
of which is fitted a disc of vulcanised india-rubber or other suitable water-
proof material. On the india-rubber disc is placed a disc of thin steel, which
is divided into two semicircular parts, or it may be made in one piece; a hole
is made in these halves to receive the vertical spindle which actuates the
index; from this central hole radical cuts are made in the spring plate, which
give it great elasticity and sensibility to pressure from beneath. The spring
plate is arranged with the central spindle and placed on the india-rubber disc,
and is secured by a metal ring screwed to the brass box. The spindle is
connected by levers, which multiply the motion to the index arranged in front
of the dial plate. The pressure of the steam on the under side of the iudia-
rubber is imparted to the spring plate which raises the spindle, and the
amount of pressure is indicated on the dial. The spring plates may be
tempered to indicate the smallest amount of pressure, or two or more plates
may be used in conjunction for extreme pressures. The interposition of the
india-rubber prevents the access of steam or moisture to the spring plate, so
that it is preserved in a thoroughly efficient condition for any length of time.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Andrew Barclay in the Great Seal Patent Office on the
10th September 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
BARCLAY, of Kilmarnock, in the County of Ayr, North Britain, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of. March, in the year of our Lord

page_text: One thousand eight hundred and sixty-two, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Andrew Barclay, Her special license that I, the said -Andrew
Barclay, my executors, administrators, and assigns, or such others as I, the
said Andrew Barclay, my executors, administrators, and assigns, should at
any time
agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
TRACTION ENGINES, AND IN APPARATUS FOR INDICATING THE PRESSURE OF STEAM,"
upon the condition (amongst others) that I, the said Andrew Barclay, my
executors or administrators, an instrument in writing under my hand and
seal, or under the hand and seal of one of them, should particularly describe
and ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Andrew Barclay, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say :-
My said Invention relates, firstly, to the arrangement and construction of
locomotive steam engines which are adapted for running on ordinary rods,
and are known as traction engines. Under one modification an ordinary
tubular locomotive boiler is arranged within a rectangular framing. The
* engine runs upon two driving wheels of larger diameter arranged towards the
front end of the engine, the backward end being supported by a single trailing
wheel fitted in the centre of the framing beneath the foot plate. The pair of
driving wheels run loosely on the main axle, and each wheel is driven by a
distinct pair of engines arranged on the opposite sides of the framing. The
main axle extends sufficiently beyond the framing to admit of the cylinders of
each pair of engines and their connected parts being arranged between the
framing and the inner faces of the driving wheels. The two cylinders on each
side are bolted to brackets projecting laterally from the framing, and they are
placed in a diagonal position, with their upper ends converging and directed
towards the driving shafts above. The upper ends of the piston rod-of each
cylinder traverses in a guide cast on the cylinder cover. The piston rods of

page_text: each pair of engines are connected to one of two crank shafts arranged
above, each shaft giving motion to one of the driving wheels, and being quite
distinct from its fellow wheel. Extending upwards from the side pieces of the
framing are two standards, in the upper parts of which are fitted the bearings
or the duplex crank shafts. One pair of engines is coupled to one of the
crank shafts on one side of the framing, and the other on the opposite side,
each having the usual eccentrics for reversing the motion of the engines. On
the opposite or free extremity of each crank shaft is a pinion, which gears into
the teeth of an annular wheel formed on the inside of the rim of each driving
wheel. The rotatory movement imparted to each crank shaft causes the pinions
to actuate the driving wheels, and so propel the machine in either direction as
desired. The eccentrics of each pair of engines are actuated by a pair of
hand levers arranged one on each side of the fire-box, similar to the ordinary
locomotive engine, and connected to the eccentrics above by a suitable
arrangement of a central lever and connecting links. The guiding of the
machine is preferred to be effected solely by the steam being caused to check
the speed of one wheel whilst that of the other is increased. This is done by
arranging the regulator so that a simple motion of the handle towards the side
on which the engine is desired to turn, will cause the steam to be partially
shut off from that pair of engines, and a larger quantity is admitted to the
other pair; the result is that the outside wheel moves with greater velocity
than the inner, and the engine is instantly turned to the right or left as
desired by the motion of the regulator handle in a corresponding direction, or
vice versa. In this way the engine driver whilst looking ahead is enabled to
turn the engine quickly in either direction without any other steering appa-
ratus. The trailing wheel or wheels may be arranged to turn to the right or
left by means of a screw if required. Another arrangement is to fit each of
the driving wheels to a tubular boss running loosely on the main axle; to this
boss is keyed a spur wheel which is driven by the pinion on the crank shaft.
This modification dispenses with the annular wheel on the inside rim of the
driving wheel. The duplex shafts may each be arranged with a coupling and
gearing to connect the shafts and reduce the speed in ascending inclines. It
is preferred to make the peripheries of the driving wheels with hexagonal or
other shaped recesses to receive wooden plugs, which are allowed to project a
little beyond the recess; as the wheel rests upon these wooden surfaces little or
no noise is made by the wheels in passing over paved roadways.
The second part of this Invention relates to the arrangement and construc-
tion of a pressure gauge.to be used with this and other engines. The apparatus

page_text: consists of a brass box forming a steam chamber, in the upper part of
which is fitted a disc of vulcanised india-rubber or other suitable waterproof
material. On the india-rubber disc is placed a disc of thin steel, which is
divided into two semicircular parts, or it may be made in one piece; a hole is
made in these halves to receive the vertical spindle which actuates the index.
From this central hole radial cuts are made in the spring plate, which give it
'great elasticity and sensibility to pressure from beneath. The spring plate is
arranged with the central spindle and placed on the india-rubber disc, and is
secured by a metal ring screwed to the brass box. The spindle is connected
by levers, which multiply the motion to the index arrange d in front of the
dial plate. The pressure of the steam on the under side of the india-rubber
is imparted to the spring plate, which raises the spindle, and the amount of
pressure is indicated on the dial. The spring plates may be tempered to
indicate the smallest amount of pressure, or two or more plates may he used
in conjunction for extreme pressures. The interposition of the india-rubber
prevents the access of steam or moisture to the spring plate, so that it is
preserved in a thoroughly efficient condition for any length of time.
And in order that my said Invention of "Improvements in Traction
Engines and in Apparatus for Indicating the Pressure of Steam" may be
properly understood, I shall now proceed to describe the several Figures on,
the explanatory Sheets of Drawings, which I have hereunto appended for the
purpose of showing certain modifications under which my improvements may
be judiciously carried out in practice, that is to say, referring to the first
modification of my improvements in traction engines as delineated in Sheet 1
of the accompanying Drawings.
Figure 1 is a longitudinal elevation of the engine; Figure 2 is a partially
sectional elevation; Figure 3, a plan of the engine, corresponding to Figure 1;
and Figure 4, an elevation, looking on the fire-box end of the engine. The
engines and their connected parts are carried on the rectangular wrought-iron
framing A, on which is arranged the spring bearings B, in which the journals
of the main driving axle C work. On the overhanging ends of the axle C
are fitted to run loosely the main driving wheels D, which support the
principal weight of the framing and engines. These wheels are arranged
beyond the centre of the framing A, and nearer to the front end of the engine,
so that the largest portion of the weight may be thrown thereon. The
wheels D are constructed with double spokes extending outwards from the
boss, and entering a rim E formed inside the periphery F, which is made with
a broad bearing surface, and inside the rim E it forms an annular wheel G, to

page_text: admit of the wheels being driven from the engines. The peripheries of the
driving wheels D are cast externally with rectangular recesses to receive the
blocks of end grain wood H; these recesses may be cast step-pitched, as
shown in the Drawing, or they may be like an ordinary cog wheel with the
blocks driven into the spaces. The object of the arrangement is to produce
an easy and noiseless rolling motion of the wheels combined with the requisite
degree of strength. The backward part of the engine framing is supported
on a single trailing wheel I, which is arranged so that when backing the
engine it may be turned either to the right or left to act as a guiding wheel,
if required. A hand wheel J gives motion to the worm K, which is in gear
with the worm wheel Lou the vertical spindle, which passes through the
tubular column M, and carries at its lower extremity a pinion N. This pinion
gears with a segmental wheel O, which is keyed on a spindle P, peudent from
the under side of the foot plate. By turning the hand wheel J, the wheel I'
is moved to the right or left, as may be desired, when the engine is backing.
The boiler Q is of the horizontal tubular kind, and arranged beneath it in
front of the fire-box is the water tank R, the supply of water to the boiler
being obtained by the injector S. The fuel boxes T are arranged on each side
of the foot plate in convenient proximity to the fire-box door. The engines
are of the class ordinarily known as "right-angled engines;" the pair of
cylinders U on each side of the. framing A lying at right angles or nearly so
to each other. The cylinders are bolted on to the shell of the boiler, and the
valve chest is arranged at the upper part of each cylinder, so that the con-
necting rods and valve gear are kept clear of the standards which carry the
driving shafts. Extending up from the framing A, between each pair of
cylinders U, is a standard or frame V, which serve to support the pair of crank
shafts W and X. These shafts are arranged parallel to each other, the pair
of engines on the right-hand side of the machine being coupled to the crank
of the shaft X, and the pair on the left to the shaft W. Each piston rod U¹
is connected to a cross head Y, which works in the guide Z, extending up
from the cylinder cover and connected to the frame V. The cross heads. Y
of each pair of engines are connected by the rods a to the contiguous crank
of the shaft W or X, and on these shafts, immediately inside the frames V,
are fitted the eccentrics b. At each side of the foot plate is fitted a reversing
lever c moving in a segmental guide, and fitted with a detent rod and lever.
The reversing lever is connected by a link d to the lever e, which is centred
on a stud in the frame V; the lower end of this lever is attached to two
reversing rods f, and these rods are jointed to the links of the eccentrics 6,

page_text: so that the valves of either pair of engines may be reversed at pleasure. The
shafts W and X have each fitted on them inside the eccentrics 6 a fly wheel g
and g', and at the extremity of each shaft opposite to that from which it is
driven is keyed a pinion h, which gives motion to the contiguous driving
wheel D, by reason of its gearing with the annular wheel G. The regulator,
which admits the steam from the boiler to the cylinders, consists of a bored
and slotted cylindrical chamber i, bolted to the smoke box tube plate, and it
has two laterally projecting branches j cast on it to admit of the connection
thereto of the steam pipes k, which convey the steam to each pair of cylinders.
Within the cylindrical chamber i is fitted a hollow barrel, which is slotted
so as to form a kind of rotatory grating. This barrel has attached to it a
rod, which extends through the steam space to the front of the boiler in the
usual way, , where it terminates in a hand lever l. This lever works laterally
in a screw guide m fixed to the front of the boiler, and the slot of this guide
being askew causes the rod of the barrel to move in a longitudinal direction
when the hand lever is put over to the right or left, so that when the slots
in the barrel and the regulator chamber agree, or are opposite to one another,
the passages are then open for the steam to flow into the cylinders by the
branch pipes k. A movement of the hand lever in the opposite direction will
obviously completely shut off the admission of the steam. In addition to this
movement provision is also made for actuating the regulator, so as to admit
steam to either pair of engines at pleasure. The rod ¹ has keyed to it the
handle n, by means of which a partially rotatory movement of the regulator
barrel may be obtained. By moving this handle to the right or left the
rotatory valve of the regulator is turned partly round, and so caused to regu-
late the quantity of steam to one pair of cylinders; in this way the speed of
one pair of engines and the wheel which they drive may be caused to work
at a reduced velocity, as compared with the other pair. By this means the
machine may be caused to move either to the right or to the left by simply regu-
lating the speed of the engines on either side, and no other steering apparatus
is required, as the engineer whilst looking forward instinctively guides the
engine by the regulator hand lever in the course he wishes it to pursue. The
funnel o is surrounded by an external casing p, similar to the spark arresters
used in the American locomotives; the object of its application to the traction
engine is to lessen the sound of the exhaust steam, which is conveyed from
the cylinders into the funnel by the exhaust k³.
Another modification of my improvements iu traction engines is delineated
in Sheet 2 of the accompanying Drawings, Figure 1 of which is a longitudinal

page_text: elevation of the engine and a passenger carriage attached thereto; Figure 2 is
a corresponding plan. In this arrangement the framing A carries the bearings
of the main axle B, on which are fitted the driving wheels C. These wheels
are generally similar in their construction, as far as regards the peripheries and
annular wheels D, to those herein-before described; but in addition to the
annular wheel each one is provided with a spur wheel E, so that the wheel C
may be driven at a certain velocity by causing the actuating pinion to gear
with the spur wheel E, and at a reduced speed when in gear with the annular
wheel D. In this modification the boiler is of the vertical tubular kind; the
square base F forms the exterior of the fire-box, from which springs the
cylindrical body of the boiler G, above which it is of increased diameter,
forming the steam space H between the exterior and the shell of the boiler.
Within the smoke box is arranged a system of four or other number of equi-
distant tubes which serve to superheat the steam; these tubes merge into the
pipe which conveys the steam to the regulator. This portion of the engine is
constructed in the same manner as the arrangement herein-before described so
far as regards the regulator chamber and its cylindrical valve. The regulator
spindle I, which extends out through the front of the boiler, has jointed to it
the hand lever K, which is pendent from the curved bar 1. above. This
arrangement admits of the longitudinal movement of the cylindrical valve or
as the fulcrum of
barrel by moving the lever K to and fro, the bar L serving
the lever, and in this way the communication between the boiler and the
regulator is opened or closed. A simple movement of the hand lever to the
right or left causes the cylindrical valve to turn partly round and shut off a
portion of the steam from either pair of eugines, according to the direction in
which the lever is turned, the eye at the upper end of the lever admitting of
its sliding along the bar L to the necessary extent. The boiler is supplied
with water from the tank M, and the fuel is carried in the box 'N, arranged
at the back of the foot plate. This form of traction engine is not provided
with either trailing or leading wheels, so that the after part of the engine is
supported by its attachment to the carriage, waggon, lorry, or other vehicle to
which it may be connected. To the front part of the tank M and to the under
side of the foot plate are bolted two brackets O, which form the footstep and
collar bearings to receive the vertical spindle of the T-shaped connecting
piece P. This part of the engine extends backwards, and has a journal formed
on it which passes through a block Q, bolted up to the under side of the
framing R of the carriage or other vehicle S. The connecting piece P is
prolonged beyond the block Q and has formed near its extremity a second
1

page_text: journal which works in the block Q, the end of the connecting piece being
secured by the jam nuts T. This arrangement of the connecting piece on the
vertical spindle allows for the movements of the two carriages in a lateral
direction, whilst the prolongation passing through the sustaining blocks Q
and Q allows for any tilting in the horizontal direction arising from the
inequalities of the road. For the heavier loads a greater amount of weight is
thrown on to the engine, and this is done by placing the wheels of the vehicle S
farther back, so as to cause the front end to bear with more force on the con-
necting piece. The cylinders U of the engines are, in this modification,
bolted to the framing A. These engines are similar in arrangement to those
before described; it will therefore be unnecessary to refer more particularly to
their several parts. Each of the crank shafts V and W carries at its extremity
a pinion X and Y, which gives motion to the contiguous driving wheel C.
The crank shafts V aud W are so arranged that they may be lifted or moved
to a slight extent so as to bring the pinions into gear either with the annular
wheels D, which would be used for heavy loads and in ascending inclines, or
with the wheels E, by which an increase in the speed is obtained. The gearing
for giving motion to the driving wheels C may be arranged so as to reduce the
speed to any required extent by having a second shaft fitted with intermediate
wheels to gear with the pinions X and Y, or by otherwise disposing the train
of gearing. On each of the crank shafts is fitted a friction break pulley Z, which
serves also as a fly wheel when the break is not in use. Either or both of the
breaks are brought into action by the lever a, which is formed of a T-shaped
figure at the inner end, and is centred on a vertical stud which is forged in one
piece with a double thimble or socket piece b. This socket piece forms the
bearing for the abutting ends of the shaft c, which is made in two parts and
serves to actuate the breaks either singly or simultaneously. The cross head
of the lever a is connected at its extremities to two vertical studs & which
extend upwards from the shaft c. If now with this arrangement the lever a is
depressed it will cause both the parts of the shaft c to turn in the forward
direction, and this movement will cause both the breaks to be applied to the
pulleys Z. But if the lever is turned to the right, that portion of the shaft c
on the same side will be turned, by means of the stud d, slightly backwards,
whilst the left-hand part moves in the opposite or forward direction, thus
causing one break pulley to be held whilst the other is free. In lieu of this
arrangement the compound movements of the breaks may be obtained by
means of three bevel wheels, one of which forms the centred end of the hand
lever a, whilst the other two are arranged in lieu of the studs d. With this

page_text: arrangement of break action the engineer is enabled to stop the motion of
both the driving wheels simultaneously, or to regulate or check the speed
of one of the wheels independently of the other, and in this way the
steering of the traction engine may be effected solely by the manipulation
of the break lever.
In Sheets 3 and 4 of the accompanying Drawings are shown my improve-
ments in pressure gauges adapted for indicating the pressure of steam in
traction engines, as well as other kinds of engines. Figure 1 on Sheet 3 is
an elevation of the gauge, partly in section; Figure 2 is a plan of the spring;
Figure 3 is a section of a duplex arrangement; and Figure 4 a corresponding
section of a triple arrangement of springs; Figure 5 is a vertical section of
the gauge chamber, showing the arrangement of the double springs; and
Figure 6 is a similar section with the triple springs. Figure 1, Sheet 4, is a
front view of the gauge with the front removed, to show the internal arrange-
ment; and Figure 2 is a vertical section taken at right angles to Figure 1.
The apparatus forming the gauge consists of a chamber A, formed of brass
or other suitable material, screwed externally, to attach it to any convenient
part of the boiler, and communicating therewith by the aperture B. The
chamber A is screwed up to a corresponding section C, which forms the lower
part of the case containing the graduated dial plate and index. In the part A
is contained an elastic diaphragm D, which is formed, by preference, of a disc
of vulcanized india-rubber. This diaphragm is placed in an annular recess
formed in the metal of the chamber A, and upon it is placed a piece of very
thin iudia-rubber, or fabric coated with india-rubber, or other suitable water-
proof material; this disc extends out to the margin of the flanges of the parts
A and C. On the disc of thin material is placed the spring E, which consists
of a thin plate of steel of a circular figure, and cut in two parts, as shown in
Figure 2. A central aperture F is made in the plate, and from this there are
several radial cuts G made in the plate with a thin saw; holes H are also
formed round the margin of the plate corresponding to the number of screws
used for connecting the parts A and C. The two halves of the spring E are
put together, so that the margin of the aperture F encircles a narrow groove
formed close to the lower end of the spindle I, the smooth extremity of which
rests on the elastic discs beneath. For extreme pressures, two or other
number of these springs may be used, in which case the central aperture of
each spring is preferred to be cut progressively larger, as shown in Figures 3
to 6, on Sheet 3. The object of the elastic diaphragm D is to prevent the
admission of steam or moisture to the spring E, and this is further guarded

page_text: against by the interposition of the thin layer of water and steamproof material
which is made to extend out to the margin of the parts A and C, so as to be
firmly enclosed. The spindle I extends up into the case J of the index, and
is connected to a small lever K carried on a stud K projecting out from a
small plate screwed to the back of the case. The connection of the lever K
with the spindle is made at a short distance from its fulcrum, so that a very
small variation in the rise and fall of the spring E will be greatly increased in
the range of the index. The lever K is connected by its free extremity. to a
tail-piece L, which forms a counterbalance to the vertical rack M. which
moves in the guide N screwed to the back of the case. The rack M is
adjusted so that it has a sight preponderance over the tail-piece L, which
keeps the rack up to the pinion O, and prevents any amount of play between
the parts. The pinion O is carried in a projecting bracket P, its spindle pro-
jecting out through the graduated dial plate Q, and carrying on its extremity
the index or pointer R. A small screw S is screwed through the bracket P.
and brought nearly in contact with the back of the rack M, so that in case
the gauge should receive any sudden jerk or violent displacement, the screw
prevents any derangement of the rack. The front part of the case is enclosed
with a plate of glass T, in the usual manner. In lieu of the vertical rack a
segmental one is preferred for actuating the pinion O, but this is a mere
matter of arrangement of detail, so also in place of the spindle I, and its
connected mechanism; a column of mercury or water may be used for
imparting by means of a float or other equivalent the motion of the dise
spring or springs, which may be seen at once in an open glass tube, or the
motion may be communicated to an index. From the simplicity of their
construction, and the nicety with which the springs E may be adjusted to
öperate, these gauges will be found more advantageous than most of the
arrangements at present in use.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe, in conclusion, that what I consider
novel and original, and therefore claim' as the Invention secured to.me by
the herein before in part recited Letters Patent, is,―
'First, the general arrangement, construction, and combination of parts
forming the two classes of traction engines, as herein-before described and
shown in Sheets 1 and 2 of the accompanying Drawings.
Second, the system or mode of arranging traction engines with right-
angled cylinder engines, each engine or pair working independently of, the

page_text: other, so that the machine may be guided by imparting varying velocities
to the driving wheels, as herein-before described and shown in the accom-
panying Drawings.
Third, the system or mode of arranging, constructing, and combining the
parts of traction engines, so that each driving wheel may be driven separately
by its own engine, or pair of engines, by their separate crank shafts, or any
other intermediate shafts which may be used for the purpose of reducing
the speed, as herein-before described.
Fourth, the system or mode of arranging, constructing, and combining the
parts of the cylindrical steam regulator for traction engines, so as to govern
the action of the engines on the other side of the machine at pleasure, as
herein-before described and shown in the accompanying Drawings.
Fifth. the application to and use of metallic disc springs in the construction
of pressure gauges, together with the arrangement and combination of parts
suitable for indicating the motion of the disc or discs when subjected to
pressure, as herein-before described and shown in the accompanying Drawings.
In witness whereof, I, the said Andrew Barclay, have hereunto set
my hand and seal, this Ninth day of September, in the year of our
Lord One thousand eight hundred and sixty-two.
ANDREW BARCLAY. (L.S.)