AN IMPROVED MINERS SAFETY LAMP
Year: 1885

page_text: I THOMAS MARSHALL of 18 Victoria Terrace Surbiton in the County of Surrey,
no occupation do hereby declare the nature of my invention for AN IMPROVED
MINERS SAFETY LAMP to be as follows:-
Being of a similar pattern as the Claney Lamp, two glasses are used, one glass A
thick and the same circumference as the Claney, but is four and three quarters of
an inch long, and the other glass B rather thin and about the same circumference
as the Stephenson lamp glass, and about three and a half inches long. Both
glasses are circular in form. The thin glass B is placed completely inside the
thick one A in the lamp, leaving a passage for air to pass between the two glasses,
the air passage to be about a quarter of an inch between them, but wider at
the top.
The inner glass is secured in its place by being fastened into two perforated
copper rings C at the bottom part of the lamp, the copper rings at the top parts
being formed to secure the bottom of the glass by a flange or collar, and the
bottom parts to be fastened to a screw ring D which is to be fitted to screw into
the bottom plate E which fastens the outer glass A. The top of the inner glass B
is secured in its place by a copper chimney F about two and three quarters of an
inch long, the top part small, and the bottom part larger and having a flange or
collar formed to fit over the top of the inner glass B. The chimney is to be cone
shaped. A perfectly flat and round piece of gauze G with a hole cut in the centre
is fastened round the chimney F just above the flange or collar, the outer edge of
the piece of gauze G is to be fastened to a collar ring H which fits over the top of
the outer thick glass A. By this means the inner glass B is secured in the centre
of the outer glass A, leaving an air passage all around and between the two glasses.
A circular gauze I is placed around and encloses the copper chimney F and flat
gauze G, the top of the gauze I being about a quarter of an inch above the top of
the chimney F, the circular gauze I to be about six and a half inches in circumference
and two and a half inches high. A sleeve gauze J is placed around the outside of
the circular gauze I, and is to be movable at the will of the Miner by raising it about
three quarters of an inch. This gauze J is to be raised, for the air to pass beneath
it through the circular gauze I for descending or ascending the mines or the light
would go out, but when the bottom is reached, is to be closed by pressing down-
wards so as to cover the circular gauze I from the bottom to within three quarters
гр.

page_text: of an inch of the top. This sleeve gauze J with the circular gauze I, forms a
double gauze against all strong currents of air. The sleeve gauze J is made with
the top part folded down like the hem of a handkercheif to cover the rough edge
and the bottom is fastened to a ring which rests on the top of the frame of the
lamp.
A perfectly flat brass top K is fixed to the lamp, the top to be fixed about three
eighths of an inch above the top of the circular gauze I. The flat top K of the
lamp to be supported upon and fixed to the frame of the lamp by four stout wire
pillars L.
The oil can M is screwed into the bottom of the lamp and locked by any of the
ordinary means. The light is placed inside the inner glass B and the air enters the
lamp in the following manner.
The air passes through the outer circular gauze I-thence downwards through the
flat round gauze G between the two glasses A and B, to the bottom of the lamp,
then it passes through the two perforated copper rings C (which are placed and fixed
together, one within the other and about, an eighth of an inch apart) to the flame
within the inner glass B, the burnt air passing upwards inside the inner glass and
then through the copper chimney F and through the top of the outer circular
gauze I out of the lamp.
By this means the lamp is perfectly secure against all draughts, and gives a
much superior light to any lamp in use, the glasses not being covered by gauze in
any way.

page_text: Improvements in miners saiеty Lamps.
I, THOMAS MARSHALL of 18 Victoria Térrace Surbiton; in the County of Surrey
do hereby declare the nature, of my invention for ▲ MINERS SAFETY LAMP and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
I
41%
The object of my invention is the production of a Lamp which will give a
greatly superior light to that of other Safety Lamps, which will be hurricane proof,
will burn steadily and well in the fiercest draughts, will not flicker, cannot be blown
out, and cannot possibly cause an explosion in the mines, except by the breaking,
of the glasses or defective workmanship.:
:
Having now particularly described and ascertained the nature of my said
Invention, and in what; manner the same is to be performed, I declare that what
I claim is particularly described in the seven claims stated at the end of this
Specification.
.
My Improved Lamp is of a similar pattern as the Clanny and Mueseler lamps
The flame is surrounded by two circular glasses. The outer cylindrical glass A is
about a quarter of an inch thick, two and a half inches in diameter, and four and
three quarters of an inch long. The inner glass B is thinner and about one and a
half inches in diameter and three and a quarter inches long, the upper end of the
said glass is smaller as shewn at b. I shall hereinafter describe four patterns of my
improved lamp, in which glasses of different lengths are used but in all cases the.
glasses A and B are of the same diameter and thickness above described, the
difference being only in the length of the said glasses.
The glass B is completely inside the glass A, leaving a passage for air of a
quarter of an inch all around between the said glasses."
The bottom of the glass B is fitted into the screw ring C which has a socket at
its upper end to receive and hold the said glass.
The lower end of the ring C is screwed into the ring plate D which receives and
holds the lower edge of the glass A and is screwed into the outer ring E of the,
lamp frame.
The top of the glass B is fitted into a chimney F which is about two and three
quarter inches long and cone shaped.
The lower end of said chimney has a socket f to receive and hold the top of
the glass B. The flat piece of gauze G forming a diaphragm has a hole in the,
centre for the reception of the chimney F around which it is bound with wire,
the outer edge of the said diaphragm G resting on the top of the glass A.
A cylindrical cap H of wire gauze, two and a half inches high, and two and one
eighth inches in diameter is fixed into the upper ring I by the collar ring K which
also fits over the top of the glass A, having the diaphragm G between it and the
said glass.
The top of the chimney F must not be more than half an inch and not less than
three eights of an inch below the top of the cap gauze H

page_text: A flat top L is fixed about a quarter of an inch above the cap gauze H and about
two and a half inches above the ring I to which it is held by the pillars M.
Around the lower portion of the gauze cap H is a sleve J of wire gauze, one
and a half inch high and two and a quarter inches diameter."
The oil reservoir N is screwed into the ring E and locked by any of the ordinary
means.
The wick tube projects above, the ring, C and the wick is operated by an
ordinary picker passing through a tube in the oil reservoir' N.
The rings E and I are united by the perpendicular pillars P, of which six or any
suitable number may be used.
Asbestos rings; or rings of leather or any other suitable material may be used
for the glass A, overlapping the edges of the said glass to protect them from the
brass or metal work!
1' I
The ring C is drilled with two rows of holes of about three sixteenths of an inch
diameter, or three rows of smaller holes; not less than one sixteenth of an inch of
unperforated metal being left above the upper and below the lower rows of holes.
A strip of wire gauze is bound around the outside of the ring C wide enough
to fully cover the plain edge of unperforated metal above and below, the holes, the
ends of the gauze being folded together like the seams of gauzes of Safety lamps,
the folding of the ends drawing the gauze perfectly tight round the ring C so as
not to leave the slightest opening other than through the holes drilled in the ring
and the parts of the gauze which covers the holes: This is important to prevent
the passing of flame.
The ring C may be recessed to receive the seam of the gauze.
It is very important that the top of the chimney F, the flat top L; and the top a
of the gauze cap H are the proper distances apart as specified to prevent the least
down-draught down the chimney which would instantly put out the light
When shorter A glasses are used I employ the special collars shewn in figure 4
in place of the collar ring K. In this figure two collars Qq are shewn united by
the shoulder R
+
The collar is one and a half inch and the collar q is five eights of an inch
measured from the shoulder R. The collar Q is formed with a fine internal screw
thread throughout its length and fitted with the screw rings T U.
The ring T is screwed up to the shoulder R to fix the gauze G and chimney F
and prevent them dropping down and exposing the flame if the glass B breaks.
The ring U is screwed in a quarter of an inch and rests on the top of the shorter
A glasses.
The depth of the collar Q may be varied according to the length of the glass A.
with which it is used.
The air entering my improved lamp passes through the gauze sleve J and cap
gauze H, thence downwards through the gauze diaphragm G between the glasses
A and B, thence through the gauze and holes roung the ring C to the flame, the
exhausted air arises through the glass B and chimney F and passes through the
upper part of the gauze cap H.
The following are the dimensions of the glasses for four patterns of my improved
lamps.
No 1 has glass A four and three quarter inches long, and glass B three and a
quarter inches long; collar K being used.
No 2 has glass A four inches long, special collar Q one inch deep and glass B
three and a quarter inches long.
.
No 3 has glass A three and a half inches long, special collar Q one and a half
inches long, and glass B three and a quarter inches long.
E
No 4 lamp is three quarters of an inch less in total length, the pillars P being
three quarters of an inch shorter. This lamp is fitted with a four inch glass 'A;
collár Kand two and a half inch glass B. It may also be fitted with a three and 5
a half inch glass A and special collar Q three quarters of an inch deep.
114

page_text: I do not confine myself to the above dimensions of glasses and collars as the same
may be varied, but if shorter glasses are used the light would be seriously
obstructed.
The gauzes and chimneys in all the above lamps are of the same dimensions,
and these and the gauze covered ring C also admit of variation without departing
from my invention.
What I claim and desire to secure by Letters Patent is
First. The combination of the outer thick cylindrical glass A, the inner thin
glass B, gauze covered perforated ring C, and chimney F, having socket f substan-
tially as herein set forth.
Second. The combination of the gauze cap H, gauze sleve J surrounding the
lower portion of the said cap gauze, diaphragm G gauze, and gauze covered
perforated ring C, through the whole of which the air passes to the flame,
constructed and arranged substantially as herein set forth.
Third. The gauze covered perforated screw ring C substantially as herein set
forth.
Fourth. The collars Qq with R and screw rings T. U. substantially as, and for
the purpose herein set forth.
Fifth. The sleve of gauze J combined with the cap of gauze H substantially
and arranged as set forth.
Sixth. The chimney F with socket f, gauze cap H and flat top L combined and
arranged substantially as herein set forth.
Seventh. The general combination and arrangement of parts of my improved
lantern, substantially as herein set forth.
Dated this Seventeenth day of August 1885