IMPROVEMENTS IN FOG-SIGNAL APPARATUS, PART OF WHICH IMPROVEMENTS IS ALSO APPLICABLE TO OTHER SIGNALLING PURPOSES
Year: 1881

page_text: LETTERS PATENT to Frederick Hale Holmes, of West Brompton, in the County
of Middlesex, Engineer, for an Invention of "IMPROVEMENTS IN FOG-SIGNAL
APPARATUS, PART OF WHICH IMPROVEMENTS IS ALSO APPLICABLE TO OTHER
SIGNALLING PURPOSES."
PROVISIONAL SPECIFICATION left by the said Frederick Hale Holmes at
the Office of the Commissioners of Patents on the 13th August 1881.
FREDERICK HALE HOLMES, of West Brompton, in the County of Middlesex,
Engineer. " IMPROVEMENTS IN FOG SIGNAL APPARATUS, PART OF WHICH
IMPROVEMENTS IS ALSO APPLICABLE TO OTHER SIGNALLING PURPOSES."
This Invention relates to the construction of the siren, and to the parts of
the apparatus for working it automatically.
In the Specification to former Letters Patent granted to me, dated 2nd October
1875, No. 3426, a siren is described which will sound one, two, or more notes
simultaneously.
According to my present Invention I make a siren that shall produce consecu-
tively a high and one or more low notes each differing in pitch, and in any desired
order, such, for example, as high, low, high or low, low, high, and so on as desired
automatically. For this purpose I employ two or more brakes or governors,
arranged in such a manner that one brake when adjusted will produce a definite
high note by regulating the speed or number of revolutions per second of the screw,
but when a second brake is made to act together with the first the friction is
increased, causing the siren to revolve with less velocity, and consequently to
produce a lower note.
In order to regulate the exact pitch of the high and low notes each brake can be
adjusted to the greatest nicity to produce the required notes.
One form of brake consists of two arms or levers hinged to the outer cylinder of
the siren on opposite sides and passing through slots in the same, so as to come in
contact with the surface of an inner cylinder fixed to the shaft or spindle of the

page_text: siren and revolving with it. These two arms or levers are hinged on to the outer
or fixed cylinder of the siren at a certain distance from one end, and the two
opposite brake arms or levers are connected at these ends by an adjustable spiral
or other spring, which on being more or less tightened lifts the two arms with more
or less force from the surface of the revolving cylinders immediately over or close
to the parts of the arms where they come in contact with the revolving cylinder.
I place over each arm a small cylinder with a piston which small cylinders are
fixed on the outer or fixed cylindrical part of the siren and are air tight. When
the compressed air or steam (which ever is used) enters these two small cylinders
the pistons are pressed down on the brake arms or levers with a force according
to the pressure of air or steam by which the self-acting siren is worked; this
pressure should always be in excess of that required, in order that the exact
normal pressure for any given note may be obtained by adjusting the spring above
mentioned which acts against the pressure on the pistons. The pressure on the
arms or levers is regulated by the size of the pistons. As the pressure acting on
the siren becomes less during the sounding the siren which is turned by that
pressure would fall off in its velocity, but by this arrangement the pressure on the
small pistons is just as much reduced, and hence the pressure on the brake is reduced
in the same proportion, and in consequence the note of the siren continues
constant.
In order to work these brakes automatically for light houses and lightship
apparatus I employ the small double valves described in my said former Specification,
which valves are acted on by cams mounted on the face of a worm wheel
making generally one turn in two minutes. These cams have hitherto been all the
same length, or in other words, stand out the same distance from the face of the
wheel. But according to my present Invention I place two (in the case of two
different notes being required) of the small double valves in a line parallel with the
axis of the worm wheel; the valve nearest the wheel is opened when the cam
passes under it, and thus acts upon the large valve admitting the air or steam to
the siren, and also to the two small pistons acting on the high note brake. The
second small double valve sends the air to the second or low note brake. The cams
for the high note only project to a sufficient extent to reach the first double valve,
whilst the cams for the low note project so as to act on both double valves. For
instance, in the order of sounding mentioned above in the first example the cams
would be short-long-short, and in the second, long-long-short, and so on; whether
the notes are two or three different notes all that is necessary is one small double
valve for each note, and the cams of such a degree of projection as to reach one,
two, or three of these valves as required.
The brake herein before described is the one I prefer to adopt, but the same
object may be effected by brakes mounted on the shaft or spindle of the siren, in
the case of two notes only being required, and in this case arms will be thrown out
by the centrifugal force against the inside of the fixed cylinder of the siren and
adjustable springs to regulate the friction. In this form of brake the second small
double valve is employed to push forward by means of a small cylinder and piston
(to which the valve admits the compressed air or steam) a clutch attached to the
second brake, which during the time of sounding the high note had its arms kept
outside the fixed cylinder by a spring, the clutch pushing forward the second brake
so that the arms thereof are within the cylinder when by their extra friction they
reduce the velocity of the siren to the lower note.
The brakes may be otherwise modified in their details whilst retaining the same
principle by which I accomplish by automatic means a change from a high to a
low note, or low to high, or low to lower, or high to higher.
The brakes may also be applied to a hand siren for ships, so that the same siren
may be made to give the shrill note of a powerful whistle and also that of a deep
and powerful fog horn.
.
In carrying out this part of my Invention the hand siren as the lever opens the
valve to let in the steam to the siren, and at the same time starts it, as described in

page_text: my said former Specification, the first brake which in this case may be either of
the two forms herein before described, or any modification of them, has its pressure
regulated by the spring, and the second brake is brought into action either by
turning a screw or by a lever being pressed down and held by a catch. By
employing a second catch for the lever a note intermediate between the fog horn
and the whistle may be produced which can be used for signalling on board steam
vessels.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frederick Hale Holmes in the Great Seal Patent Office on the
13th February 1882.
FREDERICK HALE HOLMES, of West Brompton, in the County of Middlesex,
Engineer. "IMPROVEMENTS IN FOG SIGNAL APPARATUS, PART OF WHICH
IMPROVEMENTS ARE ALSO APPLICABLE TO OTHER SIGNALLING PURPOSES."
This Invention relates to the construction of the "siren," and to the parts of
apparatus for working it automatically.
In the Specification to former Letters Patent granted to me, dated Second
October, One thousand eight hundred and seventy five, No. 3426, a siren is
described which will sound one, two, or more notes simultaneously.
According to my present Invention I make a siren that shall produce con-
secutively a high and one or more low notes, each differing in pitch and in any
desired order, such, for example, as high, low, high or low, low, high, and so on,
as desired automatically. For this purpose I employ two or more brakes or
governors, arranged in such a manner that one brake when adjusted will produce
a definite high note by regulating the speed or number of revolutions per second
of the siren, but when a second brake is made to act together with the first the
friction is increased, causing the siren to revolve with less velocity and conse-
quently to produce a lower note.
'
In order to regulate the exact pitch of the high and low notes each brake can
be adjusted to the greatest nicety to produce the required notes.
One form of brake consists of two arms or levers hinged to the outer cylinder
of the siren on opposite sides and passing through slots in the same, so as to come
in contact with the surface of an inner cylinder fixed to the shaft or spindle of the
siren and revolving with it. These two arms or levers are hinged on to the outer
or fixed cylinder of the siren at a certain distance from one end, and the two
opposite brake arms or levers are connected at these ends by an adjustable spiral
or other spring, which on being more or less tightened lifts the two arms with
more or less force from the surface of the revolving cylinders. Immediately
over or close to the parts of the arms where they come in contact with the
revolving cylinder I place over each arm a small cylinder with a piston, which

page_text: small cylinders are fixed on the outer or fixed cylindrical part of the siren and are
air tight. When the compressed air or steam (which ever is used) enters these two
small cylinders, the pistons are pressed down on the brake arms or levers with a
force according to the pressure of air or steam by which the self-acting siren is
worked; this pressure should always be in excess of that required, in order that
the exact normal pressure for any given note may be obtained by adjusting the
spring above mentioned, which acts against the pressure on the pistons. The
pressure on the arms or levers is regulated by the size of the pistons. As the
pressure acting on the siren becomes less during the sounding, the siren which is
turned by that pressure would fall off in its velocity; but by this arrangement the
pressure on the small pistons is just as much reduced, and hence the pressure on
the brake is reduced in the same proportion, and in consequence the note of the
siren continues constant.
In order to work these brakes automatically for lighthouse and light-ship
apparatus I employ the small double valves described in my said former Speci-
fication, which valves are acted on by cams mounted on the face of a worm wheel,
making generally one turn in two minutes. These cams have hitherto been all
the same length, or in other words, stand out the same distance from the face of
the wheel; but according to my present Invention I place two (in the case of two
different notes being required) of the small double valves in a line parallel with
the axis of the worm wheel; the valve nearest the wheel is opened when the cam
passes under it and thus acts upon the large valve, admitting the air or steam to
the siren, and also to the two small pistons acting on the high note brake. The
second small double valve sends the air to the second or low note brake. The
cams for the high note only project to a sufficient extent to reach the first double
valve, whilst the cams for the low note project so as to act on both double valves.
For instance, in the order of sounding, herein before mentioned in the first example,
the cams would be short-long-short, and in the second example long-long-short,
and so on.
Whether the notes are two or three different notes, all that is
necessary is one small double valve for each note, and the cams of such a degree
of projection as to reach one, two, or three of these valves as required.
The brake hereinbefore described is the one I prefer to adopt, but the same
object may be effected by brakes mounted on the shaft or spindle of the siren in
the case of two notes only being required, and in this case arms will be thrown out
by the centrifugal force against the inside of the fixed cylinder of the siren, with
adjustable springs to regulate the friction. In this form of brake the second small
double valve is employed to push forward by means of a small cylinder and piston
(to which the valve admits the compressed air or steam) a clutch attached to
the second brake, which during the time of sounding the high note had its arms
kept outside the fixed cylinder by a spring, the clutch pushing forward the second
brake, so that the arms thereof are within the cylinder, when by their extra friction
they reduce the velocity of the siren to the lower note.
The brakes may be otherwise modified in their details whilst retaining the same
principle, by which I accomplish by automatic means a change from a high to a
low note, or low to high, or low to lower, or high to higher.
The brakes may also be applied to a hand siren for ships, so that the same siren
may be made to give the shrill note of a powerful whistle, and also that of a deep
and powerful foghorn.
In carrying out this part of my Invention, as the lever opens the valve to let in
the steam to the siren, and at the same time starts it, as described in my said former
Specification, the first brake, which in this case may be either of the two forms
herein before described or any modification of them has its pressure regulated by the
spring, and the second brake is brought into action either by turning a screw or by
a lever being pressed down and held by a catch. By employing a second catch for
the lever a note intermediate between the foghorn and the whistle may be produced
which can be used for signalling on board steam vessels.
And in order that the said Invention may be fully understood, I shall now

page_text: which rest upon the levers c, c¹, as shown clearly in Figure 5. The cylindrical
holes h, h¹, are covered by a diaphragm ¹ of india rubber, metal, or other material,
preferably india rubber when compressed air is employed, but when steam is used
I employ metallic diaphragms, or dispense with them and cause the steam to act
direct on steam tight pistons. Over each diaphragm is attached a plate or cover j,
hollowed out on the under side so as to form a space or chamber at one side of the
diaphragm and piston. When compressed air or steam is admitted by the pipes
k, k, (in the manner to be hereafter explained) the diaphragms j¹ are depressed or
forced inwards, as indicated in Figure 5), and the piston i, i, forced against the
levers c, c¹, by which means the bearing surfaces f,fi, are pressed against the peri-
pheries of the brake discs g, g¹, and their revolution retarded, and with them the
slotted cylinder a of the "siren."
The cylinder a and the brake discs g, g', are upon one common spindle, as shown
clearly in Figure 2.
It will be seen that the action of springs e, e¹, is to resist the pressure
upon the diaphragms and the pistons i, ¹, but the tension of the springs and
consequently the resistance can be adjusted by means of screw hooks a¹, a, and
nuts 61, 61, thus when a given high note is required the tension of the spring e is
adjusted until the brake pressure allows the siren cylinder a to make the number
of revolutions requisite to produce the desired note, having regard to the maximum
pressure of air in the receiver. When a given low note is required in addition
to the high note the second brake is brought into operation by means of pistons i²,
levers c¹, and brake disc g', the spring e being adjusted (the other spring e. not
being interfered with) until the velocity of the revolving siren cylinder a is
reduced by the combined action of both brakes to the degree necessary to produce
the desired low note.
From this description it will be understood that when the first brake is applied
the high note is given, and when the second brake is used in addition to the first
the low note is sounded, so that on releasing the second brake the high note can be
again sounded. It will further be seen that whilst the "siren" is being sounded
the pressure of the air in the receiver will be diminishing, which would, if a
uniform resistance were maintained by the brakes, cause a diminution in the speed
of the revolving part of the siren, and consequently an alteration in the note, but
as the air pressure applied to the brakes comes from the same receiver as that from
which the siren is supplied, the pressure on the brakes decreases in the same ratio,
so that the said brakes are relieved in the same proportion, and the speed and
note remain unaltered throughout the sounding of the siren.
As it is generally required that "sirens' when used for signal stations and
light ships should sound a definite and specified note or notes, it is essential to
reduce as much as possible all liability to friction excepting that absolutely applied
by the brakes. It has been found by experience that with the sirens hitherto
constructed a small quantity of the steam or compressed air insinuated itself
between the surfaces of the revolving cylinder a and the fixed slotted cylinder A,
and created a pressure in the space between the back of the revolving cylinder a,
and the bottom of the fixed cylinder; this pressure tends to force the cylinder a, and
with it the spindle B outwards, causing friction between the side of the ratchet
wheel y and the face of the bearing of the fixed cylinder A at Z.
To obviate this I form upon or attach to the spindle B a disc or flange which
is free to revolve within an internal flange D of the outer cylinder b. The steam
or compressed air enters through the port E (and passes in the direction shown by
arrows) to the slots of the siren cylinders, whence it escapes through the horn F,
the space between the flange D and the back of the fixed cylinder A constituting
an air or steam chamber G. The diameter of the disc is such that the pressure
upon its surface counteracts the effect of the pressure in the space x, and serves to
restrain the tendency of the cylinder a to be forced outwards, by this means friction.
at Z is prevented and uncertainty in the note obviated.
When compressed air is used for operating the "siren" I employ a vessel or

page_text: receiver m as shown by Figures 7, 8, 9, and attach thereto a suitable bracket n
upon which is mounted a worm wheel o which may be revolved by means of a
screw thread p formed on the end of the main shaft of the engine and worm
teeth upon the periphery of the cam wheel as shown, or by other convenient
means.
This wheel is shown arranged to accomplish one complete revolution in two
minutes (but it may be otherwise arranged as required), and upon its side is
attached one or the other of the cams q', q³, 2³, 9', 95, 96, according to the order in
which the notes of the "siren" are to be sounded. The apparatus is shown in the
Drawings with the cam q² applied, which is arranged to sound the notes in the
following order, namely, first a high note, then again a high note and then a low
note.
The cams have on their faces long and short projections as shown, which as the
wheel revolves come into contact with one or both of the plungers of the double
valves, (These valves may be such as described in the Specification of my
before mentioned Patent.) In the arrangement shewn the operation is as follows:
-The cam wheel o revolving in the direction indicated by the arrows causes the
first short projection to operate the valve r, thereupon the compressed air passes by
pipes into the valve box t and opens the starting valve of the siren. This valve
may be constructed as described in the Specification of my before mentioned
Patent. A small quantity of compressed air then passes from the valve box t by
two pipes k, and depressing the diaphragm operates the brake pistons i and levers
c (as before described with reference to Figures 1 to 6). The high note is thus
sounded and continues to sound until the first short projection of the cam has
passed the plunger of the valve r. The sound ceases during the interval between
the projections, owing to the supply of air being discontinued. The other short
projection coming into contact with the valver causes a repetition of the operation,
and the high note is consequently again sounded and discontinued in a similar
manner. When the long projection arrives in position it presses the plunger of the
valve r and likewise of another valve ¹; this latter valve r¹ allows compressed air
to pass by the pipe ¹ to the diaphragms j¹, and to depress the pistons and the
levers c (see Figures 1 to 6 inclusive), by which means the second brake in addition
to the first is brought into operation, and by its additional friction reduces the
velocity of the siren and causes the low note to be sounded.
It will be seen by the above description and reference to Figure 11 that with the
arrangements of cams shewn six distinct series of signal sounds can be produced
by the use of a high and a low note, according to which cam q¹ to q is used,
hence a series of signal stations could be placed around the coast, each capable of
sending forth a separate signal by which it could be distinguished.
The following shews the order in which the stations might be arranged, each
using the cam according to its number thus:—

page_text: horns and sirens could be automatically sounded in cases where it is necessary to
place the motive power and pumps for supplying the air receiver at a considerable
distance from the signalling apparatus, but it is therein only shewn how one note
could be produced, and the same note repeated in quick succession two, three, or
more times at desired intervals by means of an arrangement of cams and
levers; but I am now enabled in such cases to apply my present Invention
for the automatic production of more than one note. For this purpose I employ
instead of the cam arrangement described in the before mentioned previous
Patents a cam wheel having short and long projections of a similar character to
those described with reference to Figures 7, 8, 9, and 11 of the accompanying
Drawings, together with two or more of the double valves r, r, before described;
but instead of using separate cams to be bolted on the cam wheel, I form the
wheel itself with a series of long and short projections at or near its periphery, and
(as in this case the cam wheel instead of completely revolving to produce a signal,
only rotates say, one eighth of a revolution) I arrange a repetition of the short
and long projections, say, eight times, so as to produce the required signal in each
eighth of a revolution of the wheel.
I will now proceed to explain the application of my Invention to sirens operated
by hand to give a shrill note like a whistle, and also a deep and powerful sound as
of a horn for use on board ships and for other purposes, reference being made first
to Figures 12, 13, and 14.
Instead of operating the brake by pistons and diaphragms, as hereinbefore
described with reference to Figures 1 to 6, I employ two levers c pivotted at d,
and having at one end a spring e adjustable by nuts b¹¹, and at the other end a
rod h jointed at i to one lever end, and passing through the other lever end
terminates in a screw j; k is a handled lever working over a notched quadrant 2,
and terminating in a nut m which engages with the screw j. The tension of the
spring e is so adjusted by the nuts that when the handle k is moved to the
position shewn in Figure 12 the pressure of the bearing surfaces fupon the brake
disc gallows the revolving siren cylinder a to make the requisite number of
revolutions to produce the desired high note.
When the handle is moved to the low note position, the nut m turning on the
screw draws the two ends of the levers c towards each other, and applying
additional pressure to the surfaces f reduces by its friction the velocity of the brake
disc g and cylinder a, and consequently causes the low note to be sounded.
The spindle B of the revolving cylinder a is attached by a pin or key to the
sleeve P which carries the break disc g. Friction at z is prevented by the disc v,
as explained with reference the "siren" first hereinbefore described.
According to another arrangement of my Invention, instead of using the levers c
just described, I employ the devices shown in Figures 15, 16, 17, and 18. In this
case the brake pressure is applied to the internal surface of the outer cylinder 6 by
means of plungera a, a², contained within tubes c, c', which are in communication
with the steam chamber G by holes or passages d, d.
Inclined holes are formed in the plungers a', into which enter tapers, pro-
jections, or wedges f. These wedges are carried by a collar g, which is capable of
being slid upon a feather key h by means of a forked lever i, so that when the
collar is forced towards the tubes c¹ the wedges engage with the inclined holes
and withdraw the plungers a¹ from contact with the inside of the cylinder.
When the "siren is being sounded, the shaft B, sleeve p, tubes c, c², collar g,
and wedge f, all revolve together.
When desired to sound a high note the plungers a¹ are retained out of frictional
contact with the interior of the cylinder 6 by the wedges f, and a small quantity
of steam passing through the passages d, d, enters the tubes and forces outwards the
plungers a, centrifugal force also assisting in this movement. By this means
sufficient resistance is applied to the inner surface of the cylinder to govern the
speed of the "siren" for producing the required high note. To sound the low
note the forked lever i is moved over, and the wedges withdrawn, leaving the

page_text: plungers a free to be operated by the combined steam and centrifugal force, so
that the two brakes operating together produce the desired low note.
According to another modification of my brake arrangement, I employ devices,
as shewn in Figures 19 to 23 inclusive. In this arrangement there are two
brakes which operate by centrifugal force only, one of them being constantly
in use whilst the siren is sounding, the other being capable of being put into
action when desired to sound a low note; a, a, a¹, a¹, are levers pivoted at b, which
when revolved around the centre b in the direction shewn by arrows tend to fly
outwards and to force their short arms c, c³, against the inside of the cylinder.
Taper projections or wedges d (operated by a sliding collar e and fork lever f,
somewhat similar to the last described arrangement) when moved forward engage
with the weighted tails of the levers a¹ and prevent them flying outwards.
When the wedges d are withdrawn the levers a¹ are free to act, whereupon the
combined action of the four levers a, a, a², a¹, by their frictional contact with the
inside of the cylinder cause the requisite reduction of the speed of the " siren " for
producing the low note desired.
Although I have shewn and described several ways by which a "siren " may be
caused to give high and low notes, I do not confine myself to the precise details
described, as it will be obvious that by varying the amount of pressure of the
brakes or increasing their number, more than two notes can be produced, without
in anyway departing from the principles of my Invention. It will also be obvious
that my improved "siren" may be used for other than fog signalling purposes; for
instance, it may be applied for use on railways, in dock-yards, manufactories, &c.,
for transmitting sound signals to a distance.
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 to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
First. In apparatus termed "sirens," for fog and other signalling, the use of
means, constructed, arranged, and operating essentially as hereinbefore described
under various modifications for enabling the said "sirens
to emit two or more
"
distinct notes or separate and distinguishable sounds in any required order.
Second. In apparatus termed "sirens" for fog and other signalling, the
employment of means for operating the brakes which regulate the pitch of the
note or notes by the pressure of fluid supplied from the same source, and
consequently at the same pressure as that from which the sounding portion of the
siren is supplied, for the purpose of maintaining the note or notes, substantially
as hereinbefore described.
Third. In apparatus, termed "sirens," for fog and other signalling, the use of
brake apparatus, consisting of small pistons, with or without diaphragms, combined
with levers and adjustable springs and brake discs, arranged, and operating
substantially as and for the purpose hereinbefore described.
Fourth. In apparatus termed "sirens" for fog and other signalling, the means
for automatically operating the brakes, consisting of a cam wheel and cams, by
which, according to the shape of the cam employed, high or low notes can be
sounded by the siren," and different descriptions of signals produced, substantially
as hereinbefore described.
Fifth. In "siren" signalling apparatus situated at a considerable distance from
the motive power used for charging the receiver and of the construction herein-
before mentioned, the use of a cam wheel and cams with short and long projections,
constructed and operating as and for the purpose herein before described.
Sixth. In "sirens," the use of a flange or disc (v), or its equivalent for preventing
or lessening friction when the "siren is being sounded, substantially as and for
the purpose described.
Seventh. In "sirens" operated by hand for use on board ships and such like
purposes, the use of a brake or brakes provided with means whereby the operator

page_text: is enabled to adjust or alter the siren, so that it may be capable of sounding two
or more different sounds or notes as required.
Eighth. For sirens operated by hand, the brake apparatus constructed and
arranged substantially as described with reference to Figures 12, 13, and 14 of
the accompanying Drawings, and consisting of pivotted levers, a rod and screw, and
lever nut combined with an adjustable spring or its equivalent, and a brake disc,
for the purpose specified.
Ninth. For sirens operated by hand, the brake apparatus constructed and
arranged substantially as described with reference to Figures 15, 16, 17, and 18
of, the accompanying Drawings for the purpose specified.
Tenth. For sirens operated by hand, the brake apparatus constructed and
arranged substantially as described with reference to Figures 19, 20, 21, 22, and
23 of the accompanying Drawings for the purpose specified.
In witness whereof, I, the said Frederick Hale Holmes, have to this my
Specification set my hand and seal, this Twenty-eighth day of January,
One thousand eight hundred and eighty-two.
Witness,
-
CHARLES INGREY,
Oak House,
Fulham,
S.W.
F. H. HOLMES. (L.S.)