IMPROVEMENTS IN DARK LANTERNS
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by the said Philip Blundell Bicknel
at the Office of the Commissioners of Patents on the 12th April 1880.
PHILIP BLUNDELL BICKNELL, of the City of Lincoln, late a Captain in the Army.
"IMPROVEMENTS IN DARK LANTERNS."
My Invention relates to improvements in dark lanterns for the use of policemen,
watchmen, and others, and it has for its object to remedy the defects of the
ordinary dark lantern which when carried at the waist belt sways about with the
movements of the body, and when the bullseye is obscured is apt to emit light
both at the top or chimney and round the dark slide itself, thus defeating the
object of the dark slide. Moreover it cannot be conveniently lighted and trimmed
without being removed from the belt, and when a ventilating hole is provided at
the bottom of the case any overflow of oil from the lamp is liable to escape
thereat and drop on the clothes of the wearer.
According to my Invention the lantern or case is constructed in the form of a
semicircle or rather more than a semicircle in plan in order that the back of the
lantern may lie snugly against the belt, for which purpose it may be curved
concavely to correspond to the curvature of the belt and is provided with two
belt hooks for steadier carriage instead of one as usual.
This back which also forms the door is hinged to the casing at one side, so that
when carried at the belt the lantern or case itself may be swung round on the
hinge, thus giving convenient access to the lamp without removal from the belt.
This door is boxed into the lantern and fits against a casing in such a way as to
effectually prevent the emission of light. The dark slide is curved to the form of
the lantern as usual, but instead of being placed inside the body of the lantern it
is fitted to run between the body of the lantern and an outer jacket or case
affixed thereto and in which the bullseye is mounted. The slide runs behind the
lens and no leakage of light is possible round the edges of the slide, thus ensuring
complete obscuration. The slide is operated by a projecting handle at the front

page_text: of the lamp moving in a slot in the outer jacket, and the slide is provided with a
projecting corner or nose to lessen the friction in its grooves.
The ventilating top of the lamp consists of a short chimney upon which is fitted
an inner cap with a slightly contracted aperture, enclosed by an outer cap con-
structed of a flat top plate with descending flanges surrounding the inner cap at a
sufficient distance to allow the products of combustion to escape freely and yet
effectually prevent the emission of any light. For further ventilation holes are
provided at the back of the cap screened by a strip of metal. This cap may be
made removable for cleaning. The hole in the bottom of the lantern for the
admission of air is surrounded by a rising flange to prevent the escape of any oil
that may overflow from the lamp into the body of the lantern.
In order to render the light more brilliant the wick tube is not placed in the
middle of the lantern as usual, but the focus of the lens is ascertained and the
wick placed accordingly.
·SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Philip Blundell Bicknell in the Great Seal Patent Office on the
9th October 1880.
PHILIP BLUNDELL BICKNELL, of the City of Lincoln, late a Captain in the Army.
"IMPROVEMENTS IN DARK LANTERNS."
My Invention relates to improvements in dark lanterns for the use of policemen,
watchmen, and others, and it has for its object to remedy the defects of the
ordinary dark lantern which when carried at the waist belt sways about with the
movements of the body, and when the bullseyo is obscured is apt to emit light
both at the top or chimney and round the dark slide itself, thus defeating the
object of the dark slide. The conical top now in use also admits the wind with
force sufficient to extinguish the lamp. Moreover the lamp cannot be conveniently
lighted and trimmed without being removed from the belt, and when a ventilating
hole is provided in the bottom of the case any overflow of oil from the lamp is
liable to escape thereat and drop on the clothes of the wearer.
According to my Invention the lantern or case is constructed in the form of a
semi-circle, or rather more than a semicircle in plan in order that the back of the
lantern may lie snugly against the belt, for which purpose it may be curved
concavely to correspond to the curvature of the belt, and it is provided with two
belt hooks instead of one as usual that it may be more steadily carried. This
back which also forms the door is hinged to the casing at one side, so that when
carried at the belt the lantern or case itself may be swung round on the hinge,
thus giving convenient access to the lamp without removal from the belt. This
door is boxed into the lantern and fits against a casing in such a way as to
effectually prevent the emission of light. The dark slide is curved to the form of
the lantern as usual, but instead of being placed inside the body of the lantern it

page_text: is fitted to run between the body and an outer jacket or case affixed thereto and in
which the bullseye is mounted. The slide runs behind the lens and no leakage of
light is possible round the edges of the slido, thus ensuring complete obscuration.
The slide is operated by a projecting handle at the front of the lamp moving in a
slot in the outer jacket, and the slide is provided with a projecting corner or nose
to lessen the friction in its grooves.
The ventilating top of the lamp consists of a short chimney upon which is fitted
an inner cap with a slightly contracted aperture enclosed by an outer cap con-
structed of a flat top plate with descending flanges surrounding the inner cap at a
sufficient distance to allow the products of combustion to escape freely and yet
effectually prevent the emission of any light and entirely preventing the draught
of wind blowing out the light. For further ventilation holes are provided at the
back of the cap screened by a strip of motal; this cap may be made removable for
cleaning. The hole in the bottom of the lantern for the admission of air is
surrounded by a rising flange to prevent the escape of any oil that may overflow
from the lamp into the body of tho lantorn.
In order to render the light more brilliant the wick tube is not placed in the
centro of the lantern as usual, but the focus of the lens is ascertained and the
DESCRIPTION OF DRAWINGS.
Figure 1 is a plan of the improved dark lantern; Figure 2 is a central vertical
section of the same on line 1-1, Figure 3; Figure 3 is a horizontal section on
line 2-2, Figure 2; Figure 4 is a side elevation; Figures 5, 6, and 7 are separate
views of parts of tho lantern; A is the case of the lantern; B is the usual bullseye or
lens, and C is the door of the lantern. Such lanterns are usually made cylindrical
with the door in the front and the bullsoyo mounted in the door, but in my improved
lantern the case A is made semicylindrical or rather more than a semi-cylinder, so
that it has a flat or rather concave back, which back is the door C and is hinged to
the case at one side c and secured by a hasp and staple c' at the other side. The
case or lantern A is provided with two belt hooks a to hang on the waste belt D,
and with folding wire handles a' for carrying the lantern in the hand. In
Figure 1 is shown in dotted lines how, by unfastening the door at c', the whole
lantern (except the door C) may be swung round on the hinge c thus giving con-
venient access to the interior. The door C is made with an inwardly projecting
lining or boxing d which fits in the outer casing A and lies flat against an
inwardly projecting flange or curtain d' so as to provent the emission of light around
the edges of the door. E is the dark slide fitted to run between the case A and
an outer jacket F soldered to A. The mount or rim B¹ in which the bullseye lens B
is carried is soldered to this outer jacket F instead of to the case A, and the dark
slide E being of sufficient size to completely cover the aperture and have its edges
received on all sides between A and F, no light can shine round the edges of the
slide. e is a handle fixed to the slide E and projecting through a horizontal
slot f in the outer jacket F for operating the slide.. The projecting corner or nose
on the slide E is seen at el in Figure 5 which is a separate view of the slide.
This nose c' serves to guide the slide E and make it move more easily. G is the
chimney, and H, I, a double cap fitting removably on the chimney and cutting off
rays of light while affording complete ventilation. This double cap is separately
represented in section and underside plan in Figures 6 and 7. The two caps H, I,
are rivetted together by short studs or distance pieces k. The inner cap I consists
of side flanges i which fit on the chimney G and a top plate having an aperture i¹
rather less than that of the chimey C. The outer cap H consists of a top plate
with descending side flanges h. It is larger than the inner cap I and is fixed by
the studs at the proper distance therefrom to allow of the escape of smoke, &c.
Small holes h may be provided in the back flange of the cap H screened by a
metal strip h fixed at a short distance from them. h³ is a perforated guard
all

page_text: plate fixed in the top of the outer cap Hat a short distance therefrom to prevent
the hand being burnt by touching the heated top of the cap. The chimney G and
the double cap H, I, are of the same semicircular form as the body of the lantern.
This improved ventilating top may be used in lanterns of the ordinary construction.
L is the lamp proper; it is also of semicircular form and fits in a socket rising from
the bottom of the case A; M is the hole in the bottom of the lamp for the admission
of fresh air which has access between it and the bottom of the oil pan L. The
edges of this aperture M are turned upwards sufficiently to prevent oil spilled in the
body of the lamp running out and dropping onto the clothes of the person carrying
the lantern.
..Having described the nature of my said Invention and the manner of performing
the same, I declare that what I claim as my Invention to be protected by tho
.herein before in part recited Letters Patent is,-
1st. The improved dark lantern, substantially as herein shown and described.
2nd. A dark lantern made flat or nearly flat at the back of the case, substantially
as and for the purpose specified.
3rd. A dark lantern having a flat or nearly flat door at back hinged to the case
and provided with means of attachment to the waist belt so that the whole body
of the lantern may be moved on the hinge without detaching the lantern from the
belt, substantially as and for the purpose specified.
4th. In a dark lantern the combination of the case or body of the lantern and
the outer jacket on which the lens is mounted with the dark slide arranged
to run between the two, substantially as and for the purpose set forth.
5th. In a dark lantern the dark slide fitted to run between the body of the
lantern and an outer jackot, and provided with a handle working in a slot in tho
.outer jacket, substantially as shown and described.
-6th. The ventilating top for a dark lantern consisting of an inner and outer cap
arranged, substantially as shown and described.
7th. The hole in the bottom of the lantern with upwardly turned edges,
substantially as and for the purpose specified.
In witness whereof, I, the said Philip Blundell Bicknell, have hereunto set
my hand and seal, this Eighth day of October, in the year of our Lord One
thousand eight hundred and eighty.