IMPROVE- MENTS IN PRESSURE GUAGES
Year: 1859

page_text: LETTERS PATENT to William Clark, of 53, Chancery Lanc, in the County
of Middlesex, Engineer & Patent Agent, for the Invention of "IMPROVE-
MENTS IN PRESSURE GUAGES."-A communication from Louis Droissart,
Mechanician, of Paris.
Sealed the 5th August 1859, and dated the 18th February 1859.
PROVISIONAL SPECIFICATION left by the said William Clark at the
Office of the Commissioners of Patents, with his Petition, on the
18th February 1859.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer & Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN PRESSURE GUAGES," to be as follows:-
This Invention relates to a piston pressure guage of particular form &
arrangement, which indicates the maximum pressure to which it is submitted
during its action, and also indicates, in a sure and unerring way, if the stoker
or driver have exceeded the maximum of pressure desired.
For this purpose
the steam is caused to act on a piston, which transmits its movement by means
of a series of levers to two needles, which act in unison and as one, indicating
ordinary pressures. but on a certain pressure being exceeded (that which is
proper for the boiler), these needles no longer act in concert, the one remaining
to indicate the maximum pressure which has been attained, while the other
returns towards zero, & continues to indicate the pressure which the boilers
maintains. If the pressure increases more than before, the movable needle

page_text: returns to the fixed needle and raises it to a more elevated indication, but it
returns alone, and the other remains at the highest division to which it has
been forced. On the other hand, if the pressure does not exceed the proper
limits, the needles will oscillate or move together and not separate, as described.
It will thus be understood that if the apparatus is properly closed it will be
possible to ensure perfect control over the maximum pressure at which the
boiler should be worked.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Clark in the Great Seal Patent Office on the
18th August 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CLARK, of 53, Chancery Lane, in the County of Middlesex, Engineer and
Patent Agent, send greeting.
Iler
WHEREAS Her most Excellent Majesty Queen Victoria, by Iler Letters
Patent, bearing date the Eighteenth day of February, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-second
year of er reign, did, for Herself, Ier heirs and successors, give and
grant unto me, the said William Clark, Her special licence that I, the
said William Clark, my executors, administrators, and assigns, or such
others as I, the said William Clark, my exccutors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter 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 PRESSURE GUAGES," a com-
munication from abroad by Louis Droissart, Mechanician, of Paris, in the
Empire of France, upon the condition (amongst others) that I, the said
William Clark, my executors or administrators, by an instrument in
writing under my, or their, or one of their bands and seals, should par-
ticularly 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 William Clark, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the fol-

page_text: low ng statement, reference being had to the Sheet of Drawings hereunto
annexed, and to the letters and figures marked thereon (that is to say) :-
This Invention relates to improvements in manometers or pressure guages,
whereby to indicate the maximum pressures to which they have been sub-
mitted during their action, and in fact to mark absolutely, without the possi-
bility of being tampered with by the engineer or stoker, the highest pressure
at which the boiler is worked. For this purpose, by the movement of a train
the dial plate works two needles, which move together as the pressure guage
is acted on by the steam, but these two needles do not return together to zero
if the engineer has allowed the maximum pressure which he should keep in
the boiler to be exceeded. The needle which remains to indicate the excessive
pressure is furnished with a small wheel, which rests on a fixed ratchet. This
wheel has, 1st, teeth at one part of its circumference in a certain position;
2ndly, a smooth surface round its circumference. The parts are mounted in
such manner that when the maximum pressure is arrived at the fixed ratchet
gears one tooth, whereby the second needle is prevented returning with the
first when the pressure of steam diminishes, which second needle will indicate
on the dial plate that the regulation pressure has been exceeded, and to what
extent. This latter indication results from the number of teeth of the wheel
corresponding with the number of atmospheres indicated; when the pressure
increases beyond the height last registered, the two needles will continue their
course together, but when the pressure diminishes, only one of the needles will
return to its position. If, on the contrary, the engineer has always taken care to.
keep the pressure below the maximum, the ratchet not having moved sufficiently
to gear with the teeth of the wheel, the two needles in that case will always
return to zero. Thus it will be understood, that if the apparatus is enclosed in
a safety box it is possible to have a perfect knowledge and control of the maxi-
mum pressure at which the steam boiler may work. This manometer is further
improved by a mode of closing the manometrical tube in cases of breakage,
by means of a valve actuated by the pressure of the steam, which closes it at
bottom.
This Invention also relates to a new kind of piston for the manometer,
which is represented in the annexed Drawings, which may also be applied to
the different modifications of the 1st manometer, in which I have substituted
a bent tube for the spring usually employed; this tube is closed at one extre-
mity, and having the other end in communication with the boiler, the steam
acting on this tube tends to straighten it; and thus the tube, with the aid of
the different parts connected therewith, will mark the pressure of the steam in
the boiler.

page_text: A further improvement also consists of a new application of india-rubber,
which closes the issue of the steam in the manometer.
I have represented in the annexed Drawings different kinds of manometers,
in which improvements according to this Invention are applied.
DESCRIPTION OF DRAWINGS.
Fig. 1 represents a lateral vertical section of the manometer in a plane
parallel to that of the dial plate; Fig. 2 shows a front view of the apparatus,
with a section of the inlet pipe; Fig. 3 shows a central vertical section of the
piston of the manometer: Fig. 4 shows the elevation of the piston cylinder
which forms the part of the manometer in connection with the boiler; Fig. 5
shows the mechanism of another arrangement of manometer, with a spring;
Fig. 6 shows the piston removed from the manometer; Fig. 7 shows a lateral
vertical section in a plane parallel to the dial plate of this modified manometer;
Fig. 8 shows a central vertical section of a cylinder and piston of this
manometer, as also of the steam pipe. a, case of the manometer; b, screw
union connecting it with the steam boiler; c, steam pipe; d, valve for closing
the tube of the manometer in case the steam finds any escape from any cause;
this valve answers the purpose of the ordinary stop-cocks, and tends naturally
to close the mouth of the manometer tube by the pressure of steam which
arrives underneath, and finds any issue at the upper part; e, clastic lever sus-
taining the valve; f, spiral tube, which elongates in proportion to the pressure;
9, upper guide, to permit of the vertical lengthening of the spiral tube, which
enters in a recess in the case a; h, bent lever, jointed to the case a and upper
guide g; i, wheel fixed to the extremity of the lower arm of the bent lever h;
j, wheel gearing with the wheel i; k, axis fixed to the wheel and turning with
it; 1, 1st indicating needle, represented at Fig. 2, which rotates and marks the
lower pressures; m, 2nd needle, mounted on the arbor of the first and worked
by it in the same direction; this motion is produced by the pressure of the
contact of one hand with the other.
Having described the working parts of this improved manometer, I will
now describe the same in a modified form. o, box or frame of the manometer,
enclosing the different parts which work the needles or hands; p (Fig. 2),
graduated dial, on which the needles oscillate, to indicate the degree of
pressure of the steam; q, inlet steam pipe, it is furnished in the interior with
piston on which the steam acts; r, piston, composed of a small hollow tube,
in which is fitted an india-rubber washer fixed by a screws; t, rigid rod, sliding
in the upper guide a; this rod bears on the upper part of the piston and
follows all its movements. v, antagonistic spring, wound round the rod t, and
Al

page_text: fixed to the upper part of the case; x, arm fixed to the rod t, having at its
extremity an eye in which enters a pin or gudgeon y, on a bent lever oscillating
on a point; this bent lever is jointed to another bent lever a', which latter is
connected with a boss or collar, carried by the needle arbor; c', boss or centre
carrying the second needle, which is toothed at a part of its circumference,
and is furnished with a spring acted on by a projection on the boss b'; d', spring
fixed to the bottom of case; it bears at its extremity on the boss c¹, and
taking one tooth at a time as they are presented to it in succession. The
movements of this manometer are the same as the first, that is to say, one of
the needles always stops when the normal or regulation pressure is exceeded, by
means of a catch gearing with a ratchet wheel. I will now describe the new
piston. e', piston, composed of a copper cap, f, pierced at the centre, forming
a small tube internally screwed, in which is lodged the end of a screw g¹;
this latter traverses another cap of the same diameter as the first, in which
the head of the screw lodges. Between the interior sides of the upper cap h¹
and the cylindrical head of the screw is held the end of the india-rubber tube,
in which the rod t passes; this rod rests on a small recess at the centre of the
head of the screw 9'; at the upper extremity of this tube there is a conical
cap i, the object of which is to hold the upper extremity of the india-rubber
tube against the interior of tube j'; k', screwed ferrule, serving to limit the
course of the tube. The tube j', in which the steam acts, consists of two
parts connected by a screw; this tube is terminated below by a projecting
screw, on which is screwed a nut forming the connection with the tube of the
boiler. The rod t, around which is wound the spring r, is arranged in such
manner, that when the indicating needle is at zero, the india-rubber tube is
quite tight, so as that under the influence of the pressure the piston rises
and relieves the india-rubber tube from tension. It will be easily understood
that the steam acting on the piston e forces it to rise in the tube, by this
movement, the rod t, which is in contact with this piston f', rises, distends the
spring, and imparts a forward movement to the arm x, which communicates
it to the gudgeon l' and bent lever m', which consequently acts on the coupling
collar or boss ; the pressure spring causes the second coupling collar to
participate in the motion, as also the needle it carries. So long as the pres-
sure is not in excess, or at its normal condition, according to the size of the
boiler, the two needles oscillate and indicate as one, but directly the maxi-
mum or regulation pressure is exceeded, a tooth is caused to present itself to
the spring n, with which it gears; at this moment the spring, having arrived
at the most elevated point of the cam, rises and disengages itself from tho
first coupling, and the needles separate; one of the needles then continues to

page_text: oscillate whilst the other remains stationary to indicate the maximum pressure
at which the generator has been worked.
The third modification of controlling manometer differs from the others by
the form of the tube on which the steam acts. o, box of manometer; ",
steam pipe, copper tube, which is susceptible of being elongated and
contracted according as the steam acts with more or 1. ss force; l, guide, in
which slides the tube ¹; v', wheel, having teeth on one part of its circum-
ference; on this wheel is mounted the needle, which serves to indicate tho
excessive and highest pressure of steam generated in the boiler by the stoker.
y', catch, gearing with the teeth of the wheel v', during the action of the
latter, serving to prevent the return of the indicating needle. It will be
realily understood that the steam acting on the tube has the effect of
straightening and elongating it, which consequently imparts a certain move-
ment to the lever, setting in motion the wheel u', which turns the two needles,
as also the ratchet wheel 1.
Fig. 8 represents a second modification of piston, which may be substituted
for the one represented at Fig. 9. p, inlet steam pipe; ', india-rubber
tube; s, solid cylinder of bronze, loose in the india-rubber tube q'; this
cylinder, which serves to put the spring in motion; the steam acting on it
tends to press it on the axis of the spring, which causes it to rise, and by means
of the different organs of transmission with which it is furnished it puts the
two needles in motion.
In Fig. 2, I have also represented a new arrangement of index hand or
needle, of which the object will be perfectly understood; these needles are
furnished at their short ends, the one, l, with a small notch, and the other, m,
with a button, which enters in the notch of the other needle. Thus it will be
easily understood that when the two needles are working, the one, 1, is always
kept behind the other, m, and prevented from passing by the button before
mentioned, while at the same time they are forced by this adjusting piece to
move together while the manometer works.
Having described the nature of the Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by tho
herein-before in part recited Letters Patent is,
First, the improved pressure guage or manometer for indicating the maxi-
mum pressure at which a steam boiler has been worked, by means of an
indicating needle or hand in connection therewith, which, after passing a
certain point, remains in position, as herein-before described.
Secondly, the application of a self-acting valve placed in the steam pipe to
manometers or pressure guages, as herein-before described.

page_text: Thirdly, the arrangement of the pistons and cylinders of the manometers, as
herein before described, and represented in detail in Figs. 3, 4, 6, and 8.
Fourthly, the arrangement of the parts for transmitting movement, as hercin-
before described and represented in the Drawings.
In witness whereof, I, the said William Clark, have hereunto set my
band and scal, this Eighteenth day of August, in the year of our
Lord One thousand eight hundred and fifty-nine.
Witness,
W. G. E. SWINNOCK,
53, Chancery Lane, London.
W. CLARK. (L.S.)