IMPROVED APPARATUS POR PREVENTING THE EX- PLOSION OF STEAM BOILERS
Year: 1857

page_text: LETTERS PATENT to Josiah Gimson, of Leicester, Engineer and Machinist,
for the Invention of "IMPROVED APPARATUS POR PREVENTING THE EX-
PLOSION OF STEAM BOILERS."
Scaled the 9th October 1857, and dated the 11th April 1857.
PROVISIONAL SPECIFICATION left by the said Josiah Gimson at the
Office of the Commissioners of Patents, with his Petition, on the
11th April 1857.
I, JOSIAH GIMSON, of Leicester, Engineer and Machinist, do hereby declare
the nature of the said Invention for "IMPROVED APPARATUS FOR PREVENTING
THE EXPLOSION OF STEAM BOILERS," to be as follows:-
My Invention of improved apparatus for preventing the explosion of steam
boilers has for its object to give notice to and attract the attention of the
fireman or attendant when, or rather before the level of the water in the
boiler doscends to a dangerous point, so as to create a liability to damage the
boiler, or for an explosion to take place.
My improved apparatus is so contrived, that when the level of the water
sinks below a given point an easily fusible plug or disc, made of fusible metal,
gutta percha, or some other suitable substance, becomes exposed to the action

page_text: of the steam and will be melted thereby, and the steam allowed to escape
from the boiler, and attract the attention of the attendant. I propose to
employ two of these fusible plugs or discs,, placed one below the other, so that
they may be acted upon in succession; the first before the level of the water
has sunk to a dangerous point, and which will therefore indicate that a supply
of water to the boiler is required; and the second when the level of the water
has sunk to a lower and more dangerous point. The latter will only bo acted
upon when the attendant has neglected the first warning.
The principle upon which my improved apparatus is constructed may be
carried out in a variety of ways, and the form and arrangement of the several
parts of the apparatus will depend in some measure upon the construction
of the boiler to which it is to be applied, and also upon local circumstances.
The arrangement or construction of apparatus which I have found to
answer the purpose consists principally of a bent tube or pipe, communicating
at one end with the steam space at the upper part of the boiler, and at the
other end with the water space at the lower part of the boiler. I find it
convenient that two portions of this pipe should be arranged horizontally,
one length being placed just below the point at which the level of the water
should be maintained in the boiler, and the other length at a point above
the point of danger. Each of these parts of the pipe must be provided with
a fusible metal or other plug or disc.
In order to prevent the water from circulating in the pipe I adapt thereto
asyphon. By this means, although the communication between both ends
of the bent pipe and the upper and lower parts of the boiler is maintained so
that the level of the water in both shall be always the same, yet the hot water.
from the boiler is prevented from circulating through the pipe and acting
upon the fusible plugs or discs.
An ordinary glass or other gauge may, if required, be adapted to the
apparatus to indicate the water level in the boiler, my improved apparatus
not being intended to dispense with the use of the water gauge, but simply to
prevent explosions or injury to the boiler if the indications of the water gauge
are not attended to by the fireman.
From the foregoing description it will be understood that the lower part
of the bent tube is filled with water, and the upper part with steam, and that
the water in the pipe will remain stationary and comparatively cold as long
as the water is maintained in the boiler at its proper level; but immediately
the water in the boiler sinks below that point, the water will also sink in the
tube in a corresponding degree, and the first fusible plug or disc will be left
exposed to the action of the hot steam, which will enter the pipe, melt the

page_text: fusible plug or dise, the steam will then rush out of the boiler until tho
opening is stopped up. As it would not be convenient to waste the steam
and allow it all to escape from the boiler, I adapt a cock to this opening, so
that when the alarm has been given the further rush and loss of steam may
be prevented by shutting the cock, when a supply of water may be pumped
into the boiler; but should the cock be shut to prevent the loss of steam, and
the supply of water at the same time be neglected, or inadequate, and the
level of water in the boiler be allowed to sink still lower, so as to expose the
second plug or disc, this latter will be melted, and all the steam in the boiler
will then rush out of the opening, and an explosion prevented. I do not propose
to adapt any cock to this opening, as the level of the water will have sunk to
a dangerous point, and it will be absolutely necessary that the water supply
should be at once attended to, and the boiler reinstated as before.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Josiah Gimson in the Great Seal Patent Office on the
10th October 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSIAH
GINSON, of Leicester, Engineer and Machinist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of April, in the year of our Lord One
thousand eight hundred and fifty-seven, in the twentieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, tho
said Josiah Gimson, Her special license that I, the said Josialı Gimson, my
executors, administrators, and assigns, or such others as I, the said Josiah
Gimson, my executors, 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 "IMPROVED APPARATUS
FOR PREVENTING THE EXPLOSION OF STEAM BOILERS," upon the condition (amongst
others) that I, the said Josiah Gimson, by an instrument in writing under my
hand and seal, 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.

page_text: NOW KNOW YE, that I, the said Josiah Gimson, do hereby declaro the
naturo 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 Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say):-
My Invention of "Improved Apparatus for Preventing the Explosion of
Steam Boilers" has for its object to give notice to and attract the attention of
the fireman or attendant when, or rather before the level of the water in the
boiler descends to a dangerous point, so as to create a liability to damage
the boiler, or for an explosion to take place.
My improved apparatus is so contrived, that when the level of the water
sinks below a given point an easily fusible plug or disc, made of fusible metal,
gutta percha, or some other suitable substance, becomes exposed to the action
of the steam and will be melted thereby, and the steam allowed to escapo
from the boiler, and attract the attention of the attendant. I propose to
employ two of these apparatus provided with these fusible plugs or discs, one
of which apparatus is to be placed below the other, so that they may be acted
upon in succession; the first one will be acted upon before the level of the
water has sunk to a dangerous point, and will therefore indicate that a supply
of water to tho boiler is required, while the second apparatus will be acted on
when the level of the water has sunk to a lower and more dangerous point.
The latter will only come into action when the attendant has neglected the
first warning, or been unable to replenish the boiler with water to a sufficient
extent.
The principle upon which my improved apparatus is constructed may be
carried out in a variety of ways, and the form and arrangement of the several
parts of the apparatus will depend in some measure upon the construction of
the boiler to which it is to be applied, and also upon local circumstances.
The arrangement or construction of apparatus which I have found to answer
the purpose, consists principally of a bent tube or pipe communicating at
one end with the steam space at the upper part of the boiler, and at the other
end with the water space at the lower part of the boiler. I find it convenient
that two portions of this pipe should be arranged horizontally, or nearly so,
one length being placed just below the point at which the level of the water
should be maintained in the boiler, and the other length at some point below
that, but just above the point of danger. Each of these parts of the pipe
must be provided with a fusible metal or other plug or disc, as above
⚫ mentioned.
In order to prevent the water from circulating in the pipe I adapt thereto

page_text: a syphon. By this means, although the communication between both ends of
the vent pipe and the upper and lower parts of the boiler is maintained, so
that the level of the water in both shall be always the same, yet the hot water
from the boiler is prevented from circulating through the pipe and acting
upon the fusible plugs or discs. An ordinary glass or other gauge may, if
required, be adapted to the apparatus to indicate the water level in tho
boiler, my improved apparatus not being intended to dispense with the use of
the water gauge, but simply to prevent explosions or injury to the boiler if the
indications of the water gauge are not attended to by the fireman.
Fig. 1 in the accompanying Drawing represents a transverse vertical
section of a cylindrical steam boiler with my improved apparatus adapted
thereto. a, a, is the body of the boiler; b, the cylindrical flue; c is a tube,
rising from the upper part of the boiler, and bent down at the other end, so as
to form a junction with tho horizontal tubo d, which terminates at the other
end in a junction box e; a second horizontal tube f is also connected to tho
junction box e, but at a lower level than the other tube d. The opposite end
of the horizontal tube fis bent in the form of a syphon, as shown at g, g*, tho
lower end or bent part of the syphon being formed by a junction box h, which
is placed there to receive any deposit from the pipes d and f, should any such
be likely to take place, and which deposit would otherwise be liable to
interfere with the proper operation of the apparatus. The opposite end of the
syphon communicates with the boiler, as shewn in the Drawing, and con-
sequently is always kept filled with water. i is a box, which is fitted to tho
pipe d, and contains a disc of gutta percha, or some easily fusible metal or
substance, which, when the water is drawn out of the pipe d, will be exposed
to the action of the hot steam, which will take the place of the water, and will
therefore soon become melted, and thus open a way into the atmosphere. j is
a similar box, similarly fitted to the lower tube or pipe f; one of these boxes
is shewn in front elevation at Fig. 2, and in transverse section at Fig. 3,
drawn upon an enlarged scale. k, k, is the box into the ends of which the
pipes & and fare screwed; at the bottom of the box k there is a branch pipe
1, to which may be secured a cock, as shown at m in Fig. 1, or a whistlo or
other alarm, as shewn at n in the same Figure. Immediately above and at
the entrance to the branch pipe is a cross grating o, made of metal, and
accurately fitted to a scat made for it in the box k. On the top of this grating
is placed disc of gutta percha, fusible metal, or other suitable substance, as
shown at p, and the disc p is held down on the grating o by the tubular
part of the cap piece q. A hole or opening is made through the part q* to

page_text: allow the water to pass through, and the whole is properly secured by screw
bolts and nuts, as shewn in the Figures.
From the foregoing description it will be understood that the lower parts d
and f of the bent tube are filled with water, while the upper part c is filled
with steam, and that the water in the pipes d and fand the syphon g will
remain stationary, and comparatively cold, as long as the water is maintained
in the boiler at its proper level; but immediately that the water in the boiler
sinks below that point, the water will also sink in the tube d in a corresponding
degree, and the fusible plug or disc in the box i will be left exposed to the action
of the hot steam, which will enter the pipe d and the box i and melt the fusible
plug or disc p therein, the steam will then rush out of the boiler through the
cock m until the opening is stopped up. As it would not be convenient to
waste the steam and allow it all to escape from the boiler, the cock m is adapted
to the opening of the box i, so that when the alarm has been given the further
rush and loss of steam may be prevented by shutting the cock. A supply of
water may then be pumped into the boiler, but should the cock m be shut for
the purpose of preventing the loss of steam, and the supply of water at the same
time be neglected or inadequate, the level of water in the boiler will sink still
lower, so as to expose the plug or disc in the second box j, when the disc p in
this latter will also be melted, and all the steam in the boiler will then rush
out of the opening, at the samo time sounding the whistle, and an explosion
will be prevented. I do not propose to adapt any cock to this opening, as
before the fusible disc of the boxj can be acted on the level of the water will
have sunk to a dangerous point, and it will then be absolutely necessary that
the water supply should be at once attended to, and the boiler reinstated as
before, previous to which the fire must be drawn, to prevent the boiler from
being over heated.
Having now described my "Invention of Improved Apparatus for Preventing
the Explosion of Steam Boilers," and having explained the means of carrying
the same into effect, I would remark that I do not mean or intend to confine
myself to the precise arrangement or construction of parts herein shown and
lescribed, as they must in some measure depend upon the form and position
of the boiler, and other circumstances, nor do I intend to claim the exclusivo
use or application of a plug or disc of gutta percha or fusible metal to steam
boilers for preventing the explosions of steam boilers; but that which I con-
sider to be new in the above-described improvements, and therefore desire to
claim as the Invention secured to me by Letters Patent as aforesaid, is, tho
mode herein described of applying the fusible metal or substance, so that when

page_text: the water sinks below the proper level steam will be admitted to act on the
fusible metal, but the water by not circulating through the tubes to which the
fusible metal is adapted is never liable to become heated so as to affect or
act on the fusible substance.
In witness whereof, I, the said Josiah Gimson, have hereunto set my
hand and seal, the Ninth day of Octobor, in the year of our Lord
One thousand eight hundred and fifty-seven.
JOSIAH GIMSON. (L.S.)