IMPROVEMENTS in of, for the Invention of IN LIGHTHOUSE AND OTHER LAMPS
Year: 1872

page_text: LETTERS PATENT to John Frederick Cooke Farquhar, of 24, Long Acre,
"IMPROVEMENTS
in the County of Middlesex, for the Invention of
IN LIGHTHOUSE AND OTHER LAMPS."
Sealed the 23rd August 1872, and dated the 9th March 1872.

page_text: liquid; this burner is surrounded and surmounted by a glass chimney
open at both ends and of suitable form through which the gaseous
products of combustion escape. The draught caused by that chimney
attracts the external air, both by the internal tube of the burner and by
the annular space existing between the external tube and the chimney,
thus producing a double current of air, which secures the perfect com-
bustion of the liquid of the vapour or of the gas.
In lighthouses they make use of argand burners composed of several
concentric wicks and constructed after the same principle, each wick
being separated from the next wick by an annular space through which
the air necessary for the combustion passes.
I have discovered that it is of great importance in order that the com-
bustion may be complete, the flame regular, easy to regulate, and in
order that it may reach its maximum of intensity, that the speed of the
air should be the same in all the parts of the flame, and that the parallel
columns of combustible air and gas which travel together in the chimney,
and the combustion of which produces the flame, should be rendered as
thin as possible. This condition is not fulfilled in the ordinary argand
burner with one or several wicks, the space left free between the
chimney and the external cylinder of the burner is of a greater dimen-
sion and offers consequently an easier passage to the air than the central
cylindrical space, or than the annual intermediary spaces in burners
with concentrical wicks. Moreover its opening is not on the same level
as the inferior openings of the latter, and it results from it that there
are inequalities in the speed with which the air circulates in those
various passages. This fault is especially perceptible in the lamps with
concentric wicks. The speed of the air is always greater in them on the
outside than on the inside of the burner. The consequence is that the
exterior flame cannot obtain the developement which it ought to have,
or that it can only obtain it on condition that the total draught shall be
diminished so much that it will become insufficient at the centre of the
burner, and that in that region the flame will be smoky. I remedy this
defect by surrounding the external wick with a cylinder concentric with
the external cylinder of the burner opening at the bottom at the same
height, and leaving between it and the external cylinder of the burner
an annular space equal to the annular spaces which exist between the
burners. A similar cylinder fulfilling the same conditions is placed at
the centre of the internal burner. I prefer this cylinder to be opened at

page_text: both ends so as to introduce at the centre of the flame a nucleus of air
to prevent the deformation of the internal flame. The chimney gallery
moves on the external tube, and is made in such a way that no air can
be introduced between the chimney and the external tube, and that
all the air attracted by the draught shall be forced to pass through the
annular spaces placed between the burners, and around the largest one,
it meets in all with the same resistance and it consequently acquires the
same speed. The external air tube is slightly widened at its superior
part so as not to direct the current of air to the base of the flame, the
combustion of which it would impede; besides in the lamps with fixed
oil in which the wick must rise to a certain height beyond the burner
an excess of length must be given to the external air tube equal to the
projection of the wick, so as to place as much as possible the external
wick in the same conditions of combustion as the others. I prefer to
give that excess of length with a movable ring so as not to impede the
trimming of the lamp.
In the lamps with mineral oil in which the wick goes but a very
little beyond the burner it is necessary for the external air tube to go
beyond the level of the burners. If the glass chimney be made of a
suitable diameter it is not necessary to employ an external air tube.
Having thus provided for the perfectly uniform distribution of the
air in the interior of the flame, I find it preferable to increase its density
and to secure the complete combustion of the gases by thinning the
flame, by rolling as it were by means of the particular form I give
the chimney, which is contracted opposite to the flame, so that the flame
throughout the whole length of its luminous part is contained in a
portion of the chimney which is of smaller diameter than the parts of
the chimney above and below. The combined use of those different
means allows me to obtain with an argand lamp of the same number*
and the same dimension of burners as the lamps used in the lighthouses,
an intensity of light far superior, with an expenditure of oil pro-
portionately less, either with fixed oils, vegetable or animal; or with
mineral volatile oils. Moreover the light thus obtained is more easy
to regulate, susceptible of an increase of height, and can last much longer
without trimming and without variation of intensity:
•
One of the most important principles involved in these burners with
the contracted chimneys is, that the greatest quantity of combustion
takes place in the smallest space, and for lens apparatus it will be of

page_text: great value, as a burner composed of six wicks could be used instead
of one with only four as heretofore, for by means of the contracted
chimney the luminous part of the flame would not be exfocal to the
lens apparatus and so get wasted, as would be the case if a six-wick
burner were used upon the old principle.
In the lamps with mineral oil I compress the tops of the wicks by
means of rings made in a suitable form to enter the burner tubes, so
as to compress the said wicks, and thus to equalize their action.
I use a new means of providing the burner with oil in proper
quantities and at a determined level. I arrange a float valve in an open
vessel in direct communication with the burner%3B the oil is admitted
by the valve to this supply vessel until it rises to the proper level, and
from it the oil passes to the burner, so as to stand at the same level
therein as in the supply vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Frederick Cooke Farquhar in the Great Seal
Patent Office on the 9th September 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
FREDERICK COOKE FARQUHAR, of 24, Long Acre, in the County of
Middlesex, send greeting.
.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of March in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Frederick Cooke Farquhar,
Her special license that I, the said John Frederick Cooke Farquhar,
my executors, administrators, and assigns, or such others as I, the
said John Frederick Cooke Farquhar, 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 "IMPROVEMENTS IN LIGHTHOUSE
AND OTHER LAMPS," upon the condition (amongst others), that I, the said

page_text: John Frederick Cooke Farquhar, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands
and seals, 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.
NOW KNOW YE, that I, the said John Frederick Cooke Farquhar, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :-
This Invention has for its object improvements in lighthouse and
other lamps.
The argand burner is composed of two concentric cylinders of unequal
diameters leaving between them an annular space closed at one end,
into which is introduced a cylindrical cotton wick which is supplied by
divers means with oil or combustible liquid; this burner is surrounded
and surmounted by a glass chimney open at both ends through which
the gaseous products of combustion escape. The draught caused by
that chimney attracts the external air both by the internal tube of the
burner and by the annular space existing between the external tube and
the chimney, thus producing a double current of air which secures the
perfect combustion of the vapour or of the combustible liquid.
In lighthouses they often make use of argand burners composed of
several concentric wicks, and constructed after the same principle, each
wick being separated from the next wick by an annular space through
which the air necessary for the combustion passes.
I have discovered that it is of great importance in order that the
combustion may be complete, the flame regular, easy to regulate, and
that it may reach its maximum of intensity, that the speed of the air
should be the same in and around all the parts of the flame. This'
condition is not fulfilled in the ordinary argand burner with one or
several wicks. The space left free between the chimney and the external
cylinder of the burner is of a greater dimension and offers consequently
an easier passage to the air than the central cylindrical space, or than
the annular intermediary spaces in burners with concentrical wicks.
Moreover its opening is not on the same level as the inferior openings

page_text: of the latter, and it results that there are inequalities in the speed with
which the air ascends these various passages. This fault is especially
perceptible in the lamps with concentric wicks. The speed of the air is
always greater on the outside than on the inside of the burner. The
consequence is that the exterior flame cannot obtain the developement
which it ought to have, or that it can only obtain it on condition that
the total draught shall be diminished so much that it will become in-
sufficient at the centre of the burner, and then in that region the flame
will be smoky. I remedy this defect by forming the air channel which
surrounds the external cylinder of the burner in such manner that it
opens at the bottom at the same height, and is of the same width as
the annular air spaces which exist between the burners. A similar
cylindrical air passage fulfilling the same conditions is placed at the
centre of the internal burner. I prefer this cylinder to be opened at
both ends so as to introduce at the centre of the flame a nucleus of air
to prevent the deformation of the internal flame. I also. take care in
the construction of the lamp that all the air attracted by the draught
of the chimney shall be forced to pass through the above-mentioned
air spaces, in all of which it meets with the same resistance and con-
sequently acquires the same speed. The air tubes are slightly widened
at their mouths so as not to direct the currents of air on to the base
of the flames, the combustion of which it would impede. In lamps
burning fixed oil in which the wick must rise to a certain height above
the burner tube an excess of length should be given to the external
air tube equal to the projection of the wick, so as to place as much as
possible the external wick in the same conditions of combustion as the
others. I prefer to give that excess of length by means of a movable
ring so as not to impede the trimming of the lamp.
Having thus provided for the perfectly uniform distribution of the air
in the interior of the flame, I find it preferable to increase the density
of the flame and to secure the complete combustion by the use of a
chimney, which is contracted opposite to the flame so that the flame
throughout the whole length of its luminous part is contained in a
portion of the chimney which is of smaller diameter than the parts of the
chimney above and below. The combined use of those different means
allows me to obtain, with an argand lamp of the same number and the
same dimension of burners as the lamps now used in the lighthouses, an
intensity of light far superior with an expenditure of oil proportionately

page_text: less; such is the case, either with fixed oils, vegetable or animal, or with
mineral volatile oils. Moreover, the light thus obtained is more easy to
regulate, susceptible of an increase of height, and can be left much
longer without trimming, and without variation of intensity.
One of the most important results obtained in these burners with the
contracted chimneys is that the greatest quantity of combustion takes
place in the smallest space, and for lens apparatus it will be of great.
value, as a burner composed of 6 wicks could be used instead of one with
only 4 as heretofore, for by means of the contracted chimney the lumi-.
nous part of the flame would not be exfocal to the lens apparatus and so
get wasted, as would be the case if a 6-wick burner were used upon the
old principle.
In the lamps with mineral oil I use rings made in a suitable form to
enter the burner tubes so as to compress the wicks and thus to equalise
their action. I provide the burner with oil in proper quantities, and at
a determined level, by means of a float valve in an open vessel in direct
communication with the burner. The oil is admitted by the valve to
this supply vessel until it rises to the proper level, and from it the oil
passes to the burner so as to stand at the same level therein as in the
supply vessel of the latter.

page_text: tube e and the internal tube f; g³, g², g³; g*, and 9³, are air channels
between the series of concentric tubes, they are all of the same width
and the same length, so that the air currents in all of them are of equal
velocity or approximately so. It is through these channels and through
the internal tube falone that air is able to enter the chimney / of the
lamp, for the glass gallery i fits closely upon the tube e and there is no
space between the chimney and the gallery by which air can enter.
The tubes 6¹, b¹, b³, b², b³, b³, and 64, 6', have movable rings k¹, k¹, k², k³,
k, k³, and k, k, which serve slightly to compress the wicks and keep
them truly circular at the top, as any irregular bend or fold gives rise
to an inequality in the flame, the wicks are cut off immediately over
the rings. The air after it issues from the air channels passes between
the backs of these rings which form expanded mouths or continuations
to the air channels. The external tube e receives a similar ring k. It
will be observed that this ring and the rings k¹, k¹, are deeper than the
other rings, they are so made because in practice it is found desirable
that the outermost wick should be higher than the others to compensate
to some extent for the absence of an exterior flame; h¹ is the part of
the glass chimney in which the most luminous part of the flame is
contained, it is of smaller diameter than the parts immediately beyond
it, both above and below. By the use of a chimney of this form, a very
perfect combustion is obtained, the flame has no tendency to flare, and
it is condensed into a smaller space than would be practicable with a
chimney of the usual construction; this for lighthouse lamps is a point
of very great importance.
In place of making the chimney so broad at its lower end as it is shewn
in Figure 1, it may be made of the exact size to leave the air channel g¹
of its proper width between the chimney itself and the outermost
tube 6. This construction is shewn at Figure 4, there is a socket to
receive the glass chimney formed upon the tube e. The height of the
chimney may if desired be adjusted by fitting the tube e with racks and
pinions similar to the racks and pinions' by which the gallery i can be
raised and lowered. The petroleum oil is supplied to the pipes a, a, so
that it stands about one inch and a quarter (more or less)" below the
tops of the tubes 61, 63, 63, and 6*; this is ensured by placing the pipes a
in communication with the closed chamber' m, which by the channel m"
is connected with the small cistern n. The cistern n is provided' with

page_text: a cover, but it should not fit air-tight, and the cistern is supplied by
the ordinary pressure apparatus through the pipes o and p. At the
upper end of the pipe o is a valve seat and a small valve p; and p' is a
float fixed on the stem of this valve. When the oil stands at the proper
height in the cistern n, the float closes the valve and it falls and opens
the valve as soon as the oil is drawn out of the cistern. The float shewn
in the Drawing is rather smaller in diameter than it is convenient to use
in practice. In place of supplying petroleum oil in this manner one or
more of the tubes b¹, 62, 6³, b*, may be perforated at the level at which
it is desired that the oil should stand, these perforations are covered by
an additional very thin tube, slightly larger than the perforated tube,
and the two tubes are soldered together at their lower ends, and also
above the perforations, the oil can thus flow out of the burner into the
narrow annular space so provided, and an exit passage is formed at the
bottom of the space close to one of the pipes a. The oil runs down this
pipe to a receptacle placed to receive it. The size of the additional
tube thus added to form an oil passage is such as to interfere as little as
possible with the capacity of the air channel in which it is placed.
Figure 5 is a section of a lamp adapted to burn colza or sperm oil,
here the oil is allowed to overflow at the top of the burner tubes in the
usual way. Only one ring k is employed, and this on the top of the
tube e, it stands rather higher than the projection of the wicks. The
number of wicks may be increased or diminished according as more or
less light is required,
Having thus described the nature of my said Invention, and the
manner of performing the same I would have it understood that I
claim,―
1. The construction of lighthouse and other lamps having annular
burners, but provided with air channels, arranged substantially as described
and so proportioned the one to the other that the air to supply the
flames flows through them with approximately equal velocity.
2. The arrangement of apparatus for supply of oil to the burners of
lighthouse and other lamps, substantially as described and shewn in
Figures 1 and 2 of the annexed Drawings.
3. The use in combination with a lighthouse and other lamp having
an annular burner of a chimney which is contracted opposite the flame
in such manner that the luminous part of the flame is contained in a

page_text: portion of the chimney which is of smaller diameter than the parts of
the chimney above and below the flame.
In witness whereof, I, the said John Frederick Cooke Farquhar,
have hereunto set my hand and seal, this Ninth day of Sep-.
tember in the year of our Lord One thousand eight hundred 5
and seventy-two.
JOHN FREDERICK COOKE FARQUHAR. (L.S.)