IMPROVEMENTS IN APPARATUS FOR INDICATING THE LEVEL OF WATER IN STEAM BOILERS
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office of the
Commissioners of Patents, with his Petition, on the 17th December
1863. A communication from abroad by Charles Weyher, Engineer, of
29, Boulevart St. Martin, Paris.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer and Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN APPARATUS FOR INDICATING THE LEVEL OF
WATER IN STEAM BOILERS," to be as follows:-
This Invention relates to an improved indicator of the level of water in
steam boilers, its principle being based on the elasticity of thin metal tubes,
which may be of any suitable cross section.
The principal advantages of this improved apparatus are as follows:-1st,
there is no communication however indirect between the interior of the boiler
and the atmosphere, no packing or stuffing box being required, and conse
quently the escape of steam is rendered impossible; 2ndly, the indications of
the variation in the level of the water is obtained in a much more perfect
manner than with the ordinary glass tubes; 3rdly, there is an entire absence
of irregularity in the indications, while the apparatus will last for an indefinite
time without any expense for repairs; 4thly, it may be produced at a lower
cost than that of all other apparatus of the same kind; and, lastly, the
apparatus may be readily fixed in position

page_text: Fig. 1, Sheet 1, represents a horizontal section of a boiler, showing the
arrangement of the apparatus.
a is a tube of thin metal rivetted at one end b, which is open to the side of
the boiler; the other end c is closed and carries a lever d, having a spherical
or other shaped float. On the level of the water becoming changed the float!
partakes of the movement by twisting the tube a at its end c, and in order to
transmit this motion to the outside of the boiler a rigid rod g is fitted to turn
freely in tube a, and connected to its end c by means of an index hand fixed
at h, indicating the various positions on a fixed dial i. It will be seen
that the whole acts as if the float were fixed directly to axis g, the thin tube a
simply acting as a packing.
This being understood, in order to render the apparatus of practical use, and
enable the indications to be made with clearness, I proceed as follows:-First,
it is necessary that the tube a be of such length that notwithstanding its
slight thickness its resistance to torsion may not impede the movements of the
float, and in order that the limit of the elasticity of the metal shall not be
attained, nor the elastic tube be of inconvenient length, I arrange it as shown in
Fig. 2, Sheet 1, which is a horizontal section of the apparatus. Instead of a
single tube I employ three arranged concentrically, one within the other, and
soldered together at their free ends. In this manner each tube is only a third
of the total length necessary for producing a sufficient angle of twist. These
tubes are represented by black lines in the section, the largest one being
rivetted and soldered to the brass bearing k; is a rigid tube fixed by means
of pin m to the smallest of the tubes, and also to the steel rod or axis g; said
tubel is fixed to a socket o turning freely on the end of the fixed bearing k,
and receives motion from float e, by means of arms p acting on the cast-iron
socket of the float, which socket turns freely on part k. The pin r, also
represented in Fig. 3, which is a transverse section through the axis, is
intended to limit the motion of the float, and to fix socket g to part k. The
position of the float, as also the method of transmitting its motion, will of
course vary according to the form of the boiler.
In order that the variations of level may be clearly indicated by this
improved apparatus I replace the dial and index hand by the arrangement
shown at Fig. 2, Sheet 1, and Fig. 1, Sheet 2. s is a curved plate of sheet
iron painted white or silvered, and keyed on axis q instead of the index hand
before mentioned, which curved plato oscillates behind a bar of thick glass t
fitted in the front of box u. If the float rises the curve successively presents
all its points behind the glass, which on being viewed from the outside appears
silvered at the part behind which the curve presents itself, and remains black

page_text: above, thus permitting the level of the water to be readily read from the
graduated scale v. In the foregoing apparatus I have described a silvered curve,
which in passing across the glass indicates the level of the water, instead of
which curve I may employ a triangle moving parallel to itself.