FURTHER IMPROVEMENTS IN MINERS' SAFETY LAMPS
Year: 1885

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I THOMAS MARSHALL of Dittonden, Long Ditton Hill, in the County of Surrey,
Gentleman do hereby declare the nature of my said invention for "FURTHER
IMPROVEMENTS IN MINERS' SAFETY LAMPS and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement reference being had to the accompanying drawing forming a part of
this specification
My invention relates to further improvements in the lamp for which Letters
Patent have been granted to me dated the 20th April 1885 and numbered 4840,
and the said improvements consist in providing the said lamp with a double-
acting extinguisher and in various modifications of the details of the lamp.
DESCRIPTION OF THE DRAWING.
Figure 1 is a vertical section of my improved miners' lamp, showing my
improvements.
Figures 2, 3, 4, 5, 6 and 7 are views of details of the said lamp.
In my improved lamp the collar Q, q described and claimed in the specification
of my former patent above referred to, is dispensed with.
The inner glass B is one and a quarter inch shorter than the outer glass A and
the said glass B is perfectly straight, of the same diameter throughout, and its
top and bottom edges are ground square. Both the glasses A and B are reduced
in height, and the height of the gauze cap H and sleeve J is increased. The
chimney F consists of two parts, a lower cylindrical or socket portion f and an
upper conical or tapering portion f¹. These parts may be cast in one piece as light
as possible, or the upper portion f¹ may be formed of sheet metal accurately fitted
to the lower portion f. The lower extremity of the portion f is formed as a
cylindrical socket f' for the reception of the top of the glass B and the said
portion is reduced in diameter by shoulders f³, f^ formed therein, the top edge of
the glass B butting against the under side of the shoulder f' when the chimney is
fitted over the said glass. The upper end f' of the portion f of the chimney, is
thus reduced to about two thirds of the diameter of its lower end or socket ƒ³,
and around the said end f' is fitted a ring K' which is united to the collar ring K
which fits over the top of the glass A, by means of four radiating branches or

page_text: supports K as shown in figure 4 (which is a plan of the rings when fitted in the
lamp) leaving passages for air between them. The portion f of the chimney must
be cast and turned so as to fit the glass B perfectly true, and also to fit the ring K¹
so as to permit of the vertical but not of any lateral movement of the said portion f
within the said ring. The gauze G is secured to the chimney just above the
shoulder f and the length of the glass B should be such as to press the said gauze
slightly upward. The lower edge of the gauze cap H is secured between the collar
ring K and the ring I, but the edge of the said gauze cap must not tilt the collar
ring K.
The collar ring K, ring K¹ and branches K' should be cast in one piece
and turned to ensure a correct fit.
The following are suitable dimensions for the various parts of my improved
lantern but I do not confine myself to them. Glass A a quarter of an inch thick,
two and a half or five eighths inches outer diameter and three and a half inches
long. Glass B about one and a half inch outer diameter, about two and a quarter
inches long and not less than one eighth of an inch thick. Chimney F (including
socket portion f) about four and a quarter inches long; cylindrical gauze cap H,
three and three quarter inches long, two and an eighth inches in diameter. Gauze
sleeve J three inches long, and two and a quarter inches in diameter. Flat top L
three eighths of an inch above gauze cap H. By simply shortening the pillars M,
gauzes Hand J and upper part of chimney F; and lengthening lower pillars P
longer glasses can be used. Good sizes being three and a half inches, four inches,
and four and a half inches long, the inner glasses being one and a quarter inch less
in length respectively. Thus different patterns of lamps can be had by this means,
without the special collars Qq as shown in the former patent.
My improved double-acting extinguisher is so constructed and arranged as to
extinguish the fire damp in any velocity and also extinguish the wick flame on
any attempt to open the lamp. It consists of a cap or shutter R hinged or
pivotted at R¹ through its arms or levers to the chimney F. The said cap is
shown in plan in figure 7 cut out ready to fold into proper shape. From the
levers or arms r depends a wire loop t, and a steel spring S is secured at one end
in a socket in the chimney F, the other or free end of the said spring being
connected to the projecting bar of the loop t. This spring S normally keeps the
shutter or cap R closely down upon the top of the chimney F. To the wire loop t
a wire T. passes in a vertical direction through a short tube in the chimney F the
said wire T terminating in a hook T¹ slightly below the wick-tube top O when at
tension. A combined book and lever V (figure 5) is pivotted loosely on a screw
pin V₁ to the inner side of the ring C. A loop of tape U or fine wire which will
burn by contact with a flame but will not melt with heat (tape is preferable) is
tied first the right size and then passed over the hooks T¹ and V by means of the
wire book v figure 5. The said loop U is of such a length that the cap or shutter R
is by means of the said loop, wire T and wire loopt drawn down or off the top of
the chimney F the spring S being thereby compressed. Four lever blocks Ware
secured to the wick-tube O and radiate therefrom as shown in figure 2. The wick
tube O is slightly dented or compressed at its lower end to enable the picker to be
brought in as close as possible to the wick. The screw ring m fixes the wick
tube O and blocks W into the mouth of the oil reservoir N (figure 3) which should
be fitted with a thin leather washer to prevent the oil spilling. The lower ring E
projects beyond the oil reservoir N and has a key-hole Ŷ on the right-hand side of
the ordinary screw lock, through which the stop screw X can be screwed into its
place in the screw hole X¹ in the ledge of the oil reservoir N and thickness Z which
may be soldered in where it is required. The combined hook and lever V should
be arranged on its pivot at such a distance from the collar C as to admit of the
said hook and lever being of sufficient size and to prevent their catching against
the ring C. The gauze covered ring O should have the holes closely together as
drawn, an eighth of an inch of unperforated metal above and below the holes, the
gauze to cover it fully, and the ends folded into a seam, drawing the said gauze as
tightly as possible to prevent flame passing.

page_text: To screw in or unscrew the oil reservoir N the picker should be pulled down and
inserted into the wick tube O. The extinguisher wire T and hook and lever V
must be opposite the picker when the oil reservoir N is fully fixed. When the
oil reservoir N requires but one more turn to fix it the stop screw X is screwed
into its place in the said reservoir through the key-hole Y and the turn being then
given to the reservoir N the projecting screw X is brought round to the left side
of the ordinary screw lock as shown in Figure 6, the oil reservoir being turned in
the direction of the arrows. One of the blocks W when the oil-can N is fully
screwed in may press against the lever V pushing the hook V' forward and
downward securely holding the tape U. To open the lamp, one turn of the oil
reservoir N must be given in the reverse direction of the arrows Figure 6, in order
to bring the screw X under the key-hole Y and permit of the said screw being
withdrawn. This turn or revolution of the oil-can causes the blocks W to strike
the lever V and withdraw the book V* from the loop U. The spring S then
throws the shutter or cap R over the chimney and shutting in the foul air, puts
out the wick flame and sparks, so that the flame is extinguished before the oil
reservoir can be totally unscrewed. Also the fire-damp when it enters and ignites,
burns the tape U and releases the extinguisher, shutting the chimney and putting
out the fire-damp safely in any velocity of air current, thereby ensuring a perfect
safety lamp under all conditions.
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
First. In a miners' safety lamp, the double-acting extinguisher consisting of
the cap or shutter R with levers r, spring S, wire loop t, connecting wire T, loop
of tape or other suitable material U, hook and lever V, V, lever blocks W, stop
screw X, and projecting edge of oil reservoir N with thickness Z, and projecting
ring E with key-hole Y, in combination with the ordinary screw lock, substantially
as herein described and illustrated in Figures 1, 2, 5, 6 and 7.
Second. In a miners' safety lamp, the cap or shutter R with levers r, spring S
in combination with the chimney F, and with wire loop t, and connecting wire T
or their equivalents, constructed and operating substantially as and for the purpose
herein set forth.
Third. In a miners' safety lamp, the book and lever V, V2, in combination with
lever blocks W substantially as and for the purpose herein set forth.
Fourth. In a miners' safety lamp, the atop screw X, projecting edge of oil-
reservoir N with thickness Z, projecting ring E with key-hole Y, in combination
with the ordinary screw lock, constructed and arranged substantially as and for
the purpose herein set forth.
Fifth. Constructing miners' safety lamps of different patterns with glasses A
and B of varying lengths, substantially in the manner herein set forth.
Sixth. In a miners' safety lamp, the collar ring K and ring K¹ with branches
or connecting pieces K, in combination with the chimney F, constructed and
arranged substantially as and for the purpose herein set forth, and illustrated in
figures 1 and 4.
Seventh.-The general combination and arrangements of parts of my improved
lamp, substantially as herein set forth.
Dated this seventeenth day of December AD 1885