Improvements in Safety Apparatus for Steam Boilers and the like.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Safety Apparatus for Steam Boilers and the like.
I, EMILE LERNER, of No. 31, Place de l'Hotel de Ville St. Quentin, in the
Republic of France, Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention relates to an apparatus for indicating irregularities in the working
of steam boilers, steam containers and the like.
The apparatus serves to indicate:-
1. That the level of the liquid has fallen too low while the boiler is working;
2. That this level has risen too high;
3. The intermediate position of this level;
4. That the boiler (fire) has been lighted when the boiler is insufficiently
filled with liquid;
5. That the temperature within the boiler has risen too high, which may arise
either from a too highly forced speed or from the presence of too much slime, salt
or other foreign substance which impedes the evaporation of the liquid.
A modification comprises a float and enables not only the want of liquid to
he shown, but also the other irregularities above mentioned.
The apparatus comprises a series of tubes, five for example, closed at their upper
ends by means of plugs and open at their lower ends, except the small central
tube which is closed. These various tubes are fixed in any suitable manner to
a sleeve or manhole casing conveniently bolted to the boiler.
The open ends of the tubes enter the boiler, while the closed ends of the said
tubes project outside and are surrounded by the outside air. The small central
tube is similarly arranged.
The longest of the large tubes projects downward to the lower limit of the level
of the liquid in the boiler and the shortest tube extends downwards to the upper
limit of such liquid, the other tubes project into the boiler for distances varying
between the abovementioned two extremes. The small tube extends to such a
distance into the boiler as to come into contact with the body of the fire box.
In the plugs in the upper ends of the aforesaid large tubes are fixed other
small short tubes, one of these tubes contains at its base, an instrument or con-
tact intended to make electric contact as soon as the temperature around it exceeds
a certain limit, the said contact being intended to close an electric circuit in
which is placed an electric indicator. This contact is of glass or other substance
forming a good electric msulator; it resembles an ordinary thermometer, without
graduation the substance enclosed within the vessel is mercury or other sub-
stance which is a good conductor of electricity. The contact is surrounded by
mercury or by other substance which is a good conductor of heat.
The mercury enclosed in this instrument is connected electrically with the
boiler, the boiler being connected to one pole of a battery or source of electricity.
The second large tube contains a contact identical in construction and in action
with that contained in the first tube. The said second tube which is shorter than
the first tube becomes filled with steam as soon as the level of the liquid in the

page_text: boiler falls below its lower end, establishing an electrical contact which gives
a signal different from that obtained from the contact made by the instrument
in the first tube.
The third and fourth tubes contain similar contacts but of different
construction. These contacts are inserted in the mercury or other good conductor
of heat and of electricity contained in the said tubes, they comprise a small
receiver, in which is enclosed a bad conductor of electricity either gaseous or
liquid such as air, for example; this receiver is put into communication with a
second receiver open at its upper end, by a tube of U-shape. The receivers and
the shaped tube are made of insulating material, for instance glass. The air
contained in the receiver is separated from the external air by a column of liquid
which is a good conductor of electricity, such as mercury; this liquid forms,
therefore, two levels, one in the first receiver, the other in the second receiver.
At the upper part of the first receiver is fixed, above the level of the mercury,
an electrical conductor which is fastened through the medium of the boiler to
one of the poles of the battery. A second conductor fixed to the other pole of
this battery is inserted in the mercury contained in the second receiver up to
a certain depth.
At a certain temperature, the volume of air enclosed in the first receiver will
be sufficiently large to separate the mercury from the conductor; if the tem-
perature decreases, the volume of this air decreasing at the same time, the mercury
will come into contact with the conductor, closing the circuit of the battery and
consequently putting into action a suitable signal; at a lower temperature, the
level of the mercury will rise again in the first receiver, but the level in the
second receiver having fallen while that in the first was rising, the contact between
the mercury and the conductor will be broken at this moment the electric circuit
will be opened and the signal apparatus will stop working.
The third tube at the upper part of which is arranged a contact will be filled
with steam when the level of the liquid in the boiler falls below its lower end
and filled with liquid if this latter, in the boiler, rises above this end. The
instrument or contact is so arranged that, in the first case, the volume of air
contained in the first receiver is large enough to prevent the contact of the
mercury which it contains with the conductor, and so that in the second case,
this contact will be established.
In the case of the stoppage of the boiler, the temperature in the said tube
will decrease successively and below a given temperature, the circuit of the battery
will be forcibly opened in consequence of the contraction of the air contained
in the first receiver, which contraction compelled the rising of the mercury in
this receiver and its descent in the second receiver where it is no longer in
contact with the conductor.
All that has just been said concerning the contact in the third tube applies
to the contact which is placed in the short tube fixed in the plug closing the
fourth tube with the substitution of a different level.
The small central tube is analogous to those above described with the difference
that it projects downwards below the said beforementioned tubes, it encloses as do
the first and second short tubes a contact which is fixed quite close to the place
where the highest part of the surface of the fire box is exposed to the most intense
heat.
The substance contained in the contact of the central tube-is connected elec-
trically by a wire to one of the poles of an electric battery, and by a wire fixed
in the capillary tube, to the other pole of this battery.
After what has hereinbefore been stated it will be easy to follow the working
of the apparatus. It will be readily understood that as soon as the level of the
liquid within the boiler rises or falls notice thereof is given, a special signal being
put into action when this level falls or when it rises. Moreover, for this purpose
there is used an electric indicator which may be either in sight of the stoker or
of the superintendent.

page_text: The mercury enclosed in the contacts of the first and second tubes and in the
conductors of the contacts of the third and fourth tubes are connected by the
boiler and the wire to the positive pole of a battery or other source of electricity.
The conductor fixed in the capillary tube of the instrument is connected by the
wire to an electric bell connected by a wire to the negative pole of the battery;
the conductor of the fourth contact is likewise joined to the bell by the wire.
The conductor fixed in the capillary tube of the second contact is connected by
a wire to a solenoid and thence through a wire to the negative pole of the battery,
the conductor of the third contact is connected by a wire to another solenoid and
thence by a wire to the negative pole of the battery.
The solenoids when an electric current is passing through them cause the oscil-
lation of a sector upon an axis in such a manner that different parts of it painted
in different colors, appear in the background of an opening, arranged in the lid
of the case enclosing the electric indicator.
In order that the sector may maintain its central position when there is no
current in the solenoids, a counterweight is fixed in a suitable manner to the rod
of the said sector; this rod carries, above the axis, a contact piece or armature
which is attracted by the solenoids. When the sector is displaced the counter-
weight is carried with it, and also a piece provided with two pointers which in
their oscillation come into contact with a spring blade electrically connected to
the positive pole of the battery by a wire; on the other hand, the axis is connected
to the bell. In consequence of this last arrangement each time that one of these
pointers is brought into contact with the blade, the electric circuit will be closed
and the current will ring the bell.
Supposing the level of the liquid in the boiler is between the lower ends of
the second and third tubes, then the first and second tubes are full of liquid and
the third and fourth tubes are full of steam, no electric circuit is formed, and
the weight keeps the sector in its middle position; at this moment the back-
ground visible behind the opening in the case is white.
The liquid in the boiler descending below the level of the second tube the said
tube fills with steam, the instrument closes the electric circuit, as above explained,
the current passes through the solenoid which attracts the contact piece or arma-
ture; the sector moves with this latter around its axis, the background of the
opening in the box becomes red, and the pointer passing the blade caused the
bell to ring for an instant, in consequence of the closing of the electric circuit
in which it is placed.
The stroke of the bell warns the stoker that a change has taken place in the
indicator and the red color which he now sees through the opening tells him that
the water level in the boiler is low.
Now suppose that through negligence, the attendant omits to feed more water
into the boiler; the level of the liquid therein will fall below the first or lowest
tube and such tube will fill with steam; the contact will immediately close the
electric circuit in which is placed the bell, which will continue ringing, until by
feeding water into the boiler the level of the same is raised above the said first
tube.
When the bell rises continuously, and the background seen through the opening
is red, it indicates a dangerous deficiency of liquid in the boiler.
As above stated, the level of the water in the boiler being above the lower end
of the tube the bell will stop, in consequence of the opening of the circuit caused
by the contact and the tube becomes filled with water. The filling of the boiler
being continued, the level of the second lowest tube will in its turn be passed,
and the said tube filled with water, the contact opens the circuit in which is
arranged the solenoid which does not therefore act on its armature, the sector
assumes its middle position and the background of the opening shows white;
a stroke of the bell, caused by the momentary contact of the pointer and the
blade indicates this change.
If the filling of the boiler is still continued and the level of the water is raised

page_text: above the lower end of the third tube, the said tube will become filled with water,
the contact closes the electric circuit in which is arranged the second solenoid,
this attracts the armature and with it displaces the sector, the background of the
opening shows blue, and a stroke of the bell caused by the passage of the pointer
on the blade indicates this change.
Let us assume that by negligence on the part of the attendant the filling of
the boiler is allowed to continue, the level of the liquid in the boiler will be
raised above the lower end of the fourth or highest tube which will then be filled
with water, the contact closes the circuit in which is arranged the bell, which
begins to ring continuously.
The indicator still showing blue and the bell continuing to ring, will show
that there is too much water in the boiler.
An expert and conscientious attendant will maintain the water level at such
a height that the indicator will always show white. An inferior stoker would be
instructed to commence filling so soon as the red part of the sector appears at the
opening and to continue this filling until the indicator shows blue under such
conditions the level of the liquid in the boiler will be kept at a medium and
economical position.
The contact of the small central tube produces the following effect: If the
temperature around the instrument is high enough to cause the mercury enclosed
therein to rise to the upper wire the circuit of the battery will be closed, and if
an alarm signal is placed in this circuit, it will be put in motion thereby.
This effect will be produced when the pressure in the boiler has risen too high,
when the speed of the latter has been too much forced, or even when the liquid
with which it is filled contains much slime, salt or other foreign substance
thereby retarding evaporation. The same will happen when the fire is lighted
with insufficient water in the boiler; in this case, indeed, the part of the surface
of the furnace not covered with liquid will be heated and will heat by radiation
and conductivity the contact which being kept at a temperature higher than the
normal temperature of the boiler will close the circuit of the battery and will
consequently put the indicator into action.
It is evident that as soon as that which caused the rise of the temperature
of the contact has ceased to operate, the temperature will fall, the mercury which
it contains will descend towards the bulb, thus breaking the circuit of the battery
and consequently causing the stoppage of the indicator.
It will be understood that the safety apparatus, the whole of which has just
been described in all its details, indicates:-
:-
1. The want of liquid by the indicator showing red.
2. Too much liquid by the alarm signal showing blue.
3. A low level of the liquid by the indicator showing red, and by the striking
of the bell.
4. A high level of liquid by the indicator showing blue, and by the striking
of the bell.
5. A correct level of liquid by the indicator showing white.
6. Too great a pressure by an alarm signal in the circuit (different or not)
7. Speed too much forced, by the alarm signal;
8. The presence of much slime salt or other foreign matter in the liquid, by
the alarm signal.
9. The heating of the boiler when insufficiently filled, by the alarm signal.
The advantages of the new safety apparatus which has just been described are 5
as follows:
1. Great simplicity, the net cost and size being moderate. In fact this apparatus
consists of only a small number of tubes, causing very little work and costing but
little, and of a series of small contacts like ordinary thermometers without scales,
and easily regulatable by the quantity of liquid which they contain and the
position of the electrical conductors.
2. Certainty and regularity of action. Assuming that the battery the indicator

page_text: and the electric wires are in good condition, which can be easily ascertained,
there is nothing special in the working of these arrangements in which I do
away with all guided rods which are liable to wedge and the use of floats which
might become filled with water, I also dispense with stuffing boxes which might
cause loss or too much friction. The working of the improved arrangements
are effected without friction, or any movement except the displacement of a
column of liquid. Further, no delicate mechanism is exposed to the pressure
of the boiler.
3. Ease with which the working may be controlled. All the parts relating
to these arrangements are easily accessible, the contacts can be inspected by
taking them out of their tubes. When the contacts in the first and second tubes
are heated by any means the alarm signal should work; The contacts in the
third and fourth tubes should cause the signal to work during a certain time, and
cause the blue part of the indicator to appear after lighting the boiler fire.
4. Ability to give the indications in any desired place, which permits an easy
control of the staff and an easy superintendence of the boiler by such staff.
5. Variety of operations indicated. The ordinary safety apparatus indicate,
in fact, either the want of liquid, too great fulness of the boiler, or too great a
pressure therein, but rarely combine these indications. The above described
apparatus not only gives all these indications together but further a number of
others, and will be of great use to the proprietors of boilers or steam containers
and to their staff.
According to a modification I may furnish an ordinary float indicator for boilers.
or other analogous apparatus with a small contact identical in construction and
in working that with which has just been described.
This instrument is placed in the extension of a tube on which the float works;.
the mercury which it contains is connected electrically to the boiler, the boiler
itself being connected to one of the poles of the battery by a
wire.
(It is evident that this electrical connection might be used for the apparatus.
of the type above described. Another conducting wire fixed in the capillary
tube of the contact connects it in a suitable manner with the other pole of the.
said battery: this wire is insulated along its whole course in the boiler, and it
is dispose in such a manner as not in any way to impede the free movement of.
the float.
By means of this modification it will easily be understood that the float will
indicate not only the want of liquid in the boiler by whistling, in the ordinary
way, but will also announce, by the alarm signal, arranged in the circuit of the
battery, irregularities in the working of the boiler, which were mentioned above,
when the contact of the apparatus was referred to, with which the contact of the
float is identical in all particulars.
Dated this 19th day of February 1808
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Safety Apparatus for Steam Boilers and the like,
I, EMILE LERNER, of No. 31, Place de l'Hotel de Ville St. Quentin, in the
Republic of France, Engineer, do hereby declare the nature of this invention

page_text: and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement ;-
11
This invention relates to an apparatus for indicating irregularities in the working
of steam boilers steam containers and the like.
In order that my invention may be clearly and readily understood I have repre-
sented the same in the accompanying drawing in which;-
Figure 1 is a cross section of a steam boiler fitted with my improved safety
apparatus.
Figure 2 is a plan, drawn to a larger scale, of the said apparatus.
Figure 3 is a vertical section taken on the line 3-3 of Figure 2.
Figure 4 is a vertical section taken on the line 4-4 of Figure 2.
Figure 5 is a vertical section of a modified form of the safety apparatus and
Figure 6 shows the modification Figure 5 fitted to a boiler with an internal
fire-box.
The apparatus shown in Figures 1-4 serves to indicate:--
1. That the level of the liquid has fallen too low while the boiler is working:
2. That this level has risen too high;
3. The intermediate position of this level
A. That the fire has been lighted before the boiler is sufficiently filled with
liquid.
5. That the temperature within the boiler has risen too high, which may arise
either from a too highly forced speed or from the presence of too much slime,
salt or other foreign substance which impedes the evaporation of the liquid.
The modification shown in Figures 5 and 6 comprises a float and enables not
only the deficiency of liquid to be indicated but also the other irregularities above
mentioned.
The apparatus represented in Figures 1, 2, 3, and 4 comprises a series of tubes
five, for example, a¹, a², a a¹ and a closed at their upper ends by means of
plugs and open at their lower ends (Figure 3) except which is closed as shown
in Figure 4. These various tubes are fixed in any suitable manner to a sleeve or
manhole casing conveniently bolted to the boiler.
The open ends of the tubes a, a, a, a, enter the boiler, while the closed ends
of the said tubes project outside and are surrounded by the outside air. The
small central tube the lower end of which is closed, is similarly arranged;
and may be situated in the middle of the others, as shown in Figure 2.
The tube a is the longest and projects downward to the level M N¹ the lower
limit of the level of the liquid in the boiler; the tube at is the shortest tube and
extends downwards to the level M N, the upper limit of such liquid. The
other tubes a³ and a³ are longer than a but shorter than a', they project respec-
tively to the levels M2 N2 and M3 N. The small tube a extends to such a distance
into the boiler as to come into contact with the body of the fire box.
The tube a contains in its lower portion an instrument J¹ serving to establish
electrical contact immediately the temperature which surrounds it exceeds a
certain limit, the said contact being intended to close an electric circuit, in
which is inserted an electrical annunciator. This instrument is of glass or other
good electric insulating material, and it greatly resembles an ordinary thermo-
meter, without graduation. The substance inclosed in the space e¹ should be
mercury, or some other substance which is a good conductor of electricity. The
instrument J is surrounded by mercury or some other substance which is a good
conductor of heat.
The mercury enclosed in the instrument J₁ is electrically connected with one
pole of the battery by means of the piece m (which is let into the wall of the
space el of the instrument), the metal of the tube a³, the shell of the boiler and
the wire f. The other pole of the battery is connected to the wire ¹ fixed in
the capillary tube of the instrument and terminating at such a point that, on
the temperature rising above a certain amount, the mercury within the instrument
touches it and completes the circuit of the battery.

page_text: The tube a is of suitable length in order that the instrument J¹ may be
situated in close proximity to the place at which the highest portion of the heating
surface is exposed to the greatest heat of the fire.
In the plugs c¹³c of the tubes a¹ a² a³ and a¹ are fixed small tubes
61 62 63 64
The tube contains an instrument which is identical with the instrument J¹
both as regards construction and operation. In the same way the tube 2 contains
an instrument J. The tube a2, which is shorter than the tube a¹, becomes filled
with steam immediately the level of the liquid in the boiler becomes less
than M2 N, establishing au electrical contact producing a signal different from
that which is obtained upon contact formed by the instrument J¹.
The tubes 63, 6 contain instruments similar to J1 J2 but of different construc-
tion. These instruments J3 J* being immersed in mercury or some other substance
which is a good conductor of heat and electricity contained in the tubes 63 64; they
comprise a small receiver r, in which is enclosed a bad conductor of electricity
either gaseous or liquid such as air, for example, this receiver r is put in com-
munication with a second receiver open at its upper end, by a tube s of U-shape.
The receivers r r and the U shaped tubes are made of insulating material, for
instance glass. The air contained in the receiver r is separated from the external
air by a column of liquid which is good conductor of electricity, such as mercury;
this liquid forms, therefore, two levels, one in the first receiver r, the other in
the second receiver 1 At the upper part of the first receiver r is fixed, above
the level of the mercury, an electrical conductor t which is fastened through the
medium of the boiler to one of the poles of the battery. A second conductor t¹
fixed to the other pole of this battery is inserted in the mercury contained in
the second receiver up to a certain depth.
At a certain temperature, the volume of air enclosed in the first receiver r
will be sufficiently large to separate the mercury from the conductor t; if the
temperature decreases, the volume of this air decreasing at the same time, the
mercury will again come into contact with the conductor t, closing the circuit
of the battery and consequently putting into action a suitable signal; at a lower
temperature, the level of the mercury will rise again in the first receiver r, but
the level in the second receiver having fallen while that in the first one was
rising, the contact between the mercury and the conductor will be broken; at
this moment the electric circuit will be opened and the signal apparatus will
stop working.
The third tube a³ at the upper part of which is arranged a contact J³ will be
filled with steam when the level of the liquid in the boiler falls below M³ N³ and
filled with liquid if this latter, in the boiler rises above this end M³ N³. The
contact J is so arranged that in the first case, the volume of air contained in the
first receiver r is large enough to prevent the contact of the mercury which it
contains with the conductor t and so that in the second case, this contact will
be established.
In the case of the stoppage of the boiler, the temperature in the said tube a³
will decrease successively and below a given temperature, the circuit of the
battery will be forcibly opened in consequence of the contraction of the air con-
tained in the first receiver, r, which contraction compelled the rising of the
mercury in this receiver and its descent in the second receiver where it is no
longer in contact with the conductor t¹.
All that has just been said concerning the contact J3 applied to the contact J*,
which is placed in the short tube fixed in the plug e closing the fourth tube a',
with the substitution of a different level M N for that of M³ N³.
The small central tube a is analogous to the tubes b², 62, 63, and 6', with the
difference that it projects downwards below the level ¹ N¹; said before-
mentioned tubes, it encloses as do tubes 61 and a contact which is fixed quite
close to the place where the highest part of the surface of the fire box is exposed
to the most intense heat.

page_text: The substance contained in the space e¹ of the contact J of the central tube a³
is connected electrically (Figure 1) by a wire f¹ to one of the poles of an electric
battery g, and by a wire h¹ fixed in the capillary tube j', to the other pole of this
battery g.
After what has herein before been stated it will be easy to follow the working
of the apparatus. It will be readily understood that as soon as the level of the
liquid within the boiler rises or falls notice thereof is given, a special signal being
put into action when this level falls below the lines M2 N2 and MN, or when
it rises the lines M³ N3 and M* N*. Moreover, for this purpose there is used an
electric indicator which may be either in sight of the stoker or of the superin-
tendent.
The mercury enclosed in the contacts J1, J2 of the first or second tubes a¹
and a² and in the contacts J3 and J of the third and fourth tubes 3 and a are
connected (Figure 3) by the boiler and the wire 1 to the positive pole of a battery
or other source of electricity G. The conductor fixed in the capillary tube of the
contact is connected by the wire 2 to an electric bell I, connected by a wire 3
to the negative pole of the battery G: the conductor of the fourth contact J4
is likewise joined to the bell by the wire 4. The conductor fixed in the capillary
tube of the second contact J2 is connected by a wire 5 to a solenoid S₁ and thence
through a wire 6 to the negative pole of the battery G; the conductor t' of the
third contact J³ is connected by a wire 7 to another solenoid S and thence by a
wire. 8 to the negative pole of the battery G.
The solenoids S¹ S2, when an electric current is passing through them, cause the
oscillation of a sector U upon an axis in such a manner that different parts of it
painted in different colours, appear in the background of an opening & arranged
in the lid of the case enclosing the electric indicator.
In order that the sector U may maintain its central position when there is no
current in the solenoids, a counterweight is fixed in a suitable manner to
the rod w of the said sector; this rod carries, above the axis 0, a contact piece R
or armature which is attracted by the solenoids. When the sector U is displaced,
the counterweight is carried with it and also a piece X provided with two
pointers yy which in their oscillation come into contact with a spring blade z,
electrically connected to the positive pole of the battery G by a wire 9; on the other
hand, the axis O is connected to the bell I by a wire 10. In consequence of this
last arrangement each time that one of these pointers y¹ or y² is brought into
contact with the blade z, the electric circuit will be closed and the current will
ring the bell I.
Supposing the level of the liquid in the boiler is between M2 N2 and M³ N³;
the tubes a and a² are full of liquid and the tubes a³ a are full of steam, no
electric circuit is formed, and the weight keeps the sector U in its middle
position; at this moment the background visible behind the opening in the case
is white.
The liquid in the boiler descending below the level M2 N2; the said tube a²
fills with steam, the contact Ja closes the electric circuit, as above explained, the
current passes through the solenoid S¹, which attracts the contact piece or arma-
ture R the sector U moves with this latter around its axis 0, the background of
the opening in the box becomes red, and the pointer y passing the blade z causes
the bell I to ring for an instant, in consequence of the closing of the electric
circuit in which it is placed.
The stroke of the bell warns the stoker that a change has taken place in the
indicator and the red color which he now sees through the opening a tells him that
the water level in the boiler is low.
Now suppose that through negligence, the attendant omits to feed more water
into the boiler; the level of the liquid therein will fall below M N¹, and the
tube a will fill with steam; the contact J will immediately close the electric
circuit in which is placed the bell I, which will continue ringing until by feeding
4

page_text: vater into the boiler the level of the same is raised above M¹ N. H is an electric
bell.
When the bell I rings continuously and the background seen through the
pening is red, it indicates a dangerous deficiency of liquid in the boiler."
As above stated, the level of the water in the boiler being above M', N¹, the
bell I will stop, in consequence of the opening of the circuit caused by the
contact J¹ and the tube becomes filled with water." The filling of the boiler being
continued, the level M² N³ will in its turn be passed, and the said tube a² is
filled with water, the contact J2 opens the circuit in which is arranged the
solenoid S which does not therefore act on its armature, the sector assumes its
middle position and the background of the opening shows white; a stroke of
the bell, caused by the momentary contact of the pointer y and the blade =
indicates this change.
If the filling of the boiler is still continued and the level of the water is raised
above M3 N³ the said tube a³ will become filled with water, the contact J closes
the electric circuit in which is arranged the second solenoid S2, this attracts the
armature R and with it displaces the sector U, the background of the opening a
shows blue, and a stroke of the bell caused by the passage of the pointer on
the blade indicates this change.
Let us assume that through negligence on the part of the attendant the filling
of the boiler is allowed to continue the level of the liquid in the boiler will be
raised above M N, the tube at will then be filled with water, the contact J*
closes the circuit on which is arranged the bell I, which begins to ring con-
tinuously.
The indicator still showing blue and the bell I continuing to ring, will show
that there is too much water in the boiler.
!
An expert and conscientious attendant will maintain the water level at such
a height that the indicator will always show white. An inferior stoker would
be instructed to commence filling so soon as the red part of the sector appears
at the opening a, and to continue this filling until the indicator shows blue;
under such conditions the level of the liquid in the boiler will be kept at a
medium and economical position.
The contact J of the small central tube produces the following effect: If
the temperature round the instrument (Figures 1 and 4) is high enough to
cause the mercury enclosed therein to rise to the upper wire ', the circuit of
the battery g will be closed, and of an alarm signal is placed in this circuit,
it will be put in motion thereby.
This effect will be produced when the pressure in the boiler has risen too high,
when the generation of steam has been too much forced, or even when the liquid
with which it is filled contains much slime, salt, or other foreign substance
thereby retarding evaporation. The same will happen when the fire is lighted
with insufficient water in the boiler; in this case, indeed, the part of the surface
of the furnace not covered with liquid will be heated and will heat by radiation
and conductivity the contact J which being kept at a temperature higher than
the normal temperature of the boiler will close the circuit of the battery g and
will consequently put the indicator into action.
It is evident that as soon as that which caused the rise of the temperature of
the contact J has ceased to operate, the temperature will fall, the mercury which
it contains will descend towards the bulb e¹, thus breaking the circuit of the
O battery g, and consequently causing the stoppage of the indicator i¹.
5
It will be understood that the safety apparatus, the whole of which has just
been described in all its details, indicates:-
1. The want of liquid by the indicator showing red.
2. Too much liquid by the indicator showing blue.
3. A low level of the liquid by the indicator showing red and by the ringing
of the bell.

page_text: 4. A high level of liquid by the indicator showing blue, and by the ringing
of the bell.
5. A correct level of liquid by the indicator showing white.
6. Too great a pressure by an alarm signal in the circuit (different or not).
7. Generation of steam too quickly by the alarm signal.
8. The presence of much slime, salt or other foreign matter in the liquid by
the alarm signal.
9. The heating of the boiler when insufficiently filled by the alarm signal.
The advantages of the new safety apparatus which has just been described are
as follows:
1. Great simplicity the net cost and size being moderate. In fact this
apparatus consists of only a small number of tubes, causing very little
work and costing but little, and of a series of small contacts like ordinary thermo-
meters without scales, and easily regulated by the quantity of liquid which they
contain and the position of the electrical conductors.
2. Certainty and regularity of action. Assuming that the battery, the indi-
cator, and the electric wires are in good condition, which can be easily ascertained
there is nothing special in the working of these arrangements, in which I do away
with all guided rods which are liable to wedge and the use of floats which might
become filled with water. I also dispense with stuffing boxes which might causo
loss or too much friction. The working of the improved arrangements, are
effected without friction, or any movement except the displacement of a column
of liquid. Further, no delicate mechanism is exposed to the pressure of the
boiler.
3. Ease with which the working may be controlled. All the parts relating to
these arrangements are easily accessible, the contacts J1 J2, J³, J, can be inspected
by taking them out of their tubes. When the contacts J J2 are heated by any
means, the alarm signal should work.
The contacts J3 J4 should cause the signal to work during a certain time, and
cause the blue part of the indicator to appear after lighting the boiler fire.
4. Ability to give the indications in any desired place, which permits an easy
control of the staff and an easy superintendence of the boiler by such staff.
5. Variety of operations indicated. The ordinary safety apparatus, indicates
in fact either the want of liquid, too great fulness of the boiler, or too great a
pressure therein, but rarely combine these indications. The above described
apparatus not only gives all these indications together, but further a number of
others, and will be of great use to the proprietors of boilers or steam containers
and to their staff.
According to a modification represented in Figures 5 to 6 I may furnish an
ordinary indicator for boilers or other analogous apparatus with a small contact
identical in construction and in working with J of the apparatus which has just
been described.
This instrument J is placed in the extension of a tube d on which the float F
works; the mercury which it contains is connected electrically to the boiler by
a piece m. the boiler itself being connected to one of the poles of the battery g
by a wire n. It is evident that this electrical connection might be used for the
apparatus of the type shown in Figures 1, 2, and 3. Another conducting wire h
fixed in the capillary tube of the contact J, connects it in a suitable manner
with the other pole of the said battery: this wire his insulated along its whole,
course in the boiler, and it is disposed in such a manner as not in any way
to impede the free movement of the float F.
By means of this modification it will easily be understood that the float F will
indicate not only the want of liquid in the boiler by whistling, in the ordinary
way, but will also announce, by the alarm signal i, arranged in the circuit of the
battery g, irregularities in the working of the boiler, which were mentioned above,

page_text: when the contact J of the apparatus was referred to, with which the contact J
of the float F is identical in all particulars.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that
what I claim is:
1. A safety apparatus for boilers and other steam containers comprising a
number of tubes (a', a², a³, a³) closed at one of their ends, and the open extremities
of which are inserted to different depths in the boiler, the closed ends being sur-
rounded by the open air, each of these tubes having arranged in its upper part, in a
short tube of small diameter (6', 62, 63, 6), a contact, those extending below the
normal level of the liquid, with a contact (I, J), and those extending only to this
level with a contact (J3, J) the said contacts being intended to produce electrical
connection, and the whole of the apparatus being intended to indicate the varia-
tions of level of the liquid in the boiler, substantially in the manner and under
the conditions above specified with reference to the drawing.
2. The combination of the apparatus forming the subject of Claim 1, with an
electric indicator indicating and signalling the irregularities in the working of
such apparatus, the whole operating in the manner and under the conditions
hereinbefore described with reference to the accompanying drawing.
3. The combination with the apparatus forming the subject of Claim 1, of a
fifth tube (7) enclosing an electrical contact of the kind contained in the two
first tubes of the said apparatus, this fifth tube extending downwards to a certain
distance from the surface of the furnace, and intended to complete the indications
given by the four first tubes, in the manner and under the conditions above
specified with reference to the accompanying drawing.
4. As a modified form of the apparatus forming the subject of the preceding
claims, the application of a contact of the kind contained in the two first tubes
of the said apparatus to the lower part of the float indicator of a boiler or steam
container, which contact will indicate a certain irregularity in the working of
this boiler or container, in the manner and under the conditions above specified
with reference to the accompanying drawing.
Dated this 10th day of November 1898
1
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.