IMPROVEMENTS IN SAFETY LAMPS
Year: 1866

page_text: LETTERS PATENT to Evan Thomas, of Aberdare, in the County of
Glamorgan, Ironmonger and Safety Lamp Manufacturer, for the Inven-
tion of "IMPROVEMENTS IN SAFETY LAMPS."
Sealed the 17th May 1867, and dated the 20th November 1866.
PROVISIONAL SPECIFICATION left by the said Evan Thomas at the
Office of the Commissioners of Patents, with bis Petition, on the
20th November 1866.
I, EVAN THOMAS, of Aberdare, in the County of Glamorgan, Ironmonger
and Safety Lamp Manufacturer, do hereby declare the nature of the said
Invention of "IMPROVEMENTS IN SAFETY LAMPS," to be as follows:-
This Invention has for its object the rendering the ordinary miners' safety.
Jamps more secure by the adoption of arrangements which prevent the glasses
from becoming loose, and so preventing the entry of the foul gases into the
lamps.
According to the present ordinary construction of miners' safety lamps the
glass is held in the lamp by means of a plain or flat metal ring, which fits into
a screw on the lower part of the frame of the lamp and bears directly against
the bottom of the glass, no allowance being made for expansion of the glass
and hence the frequent fracture of lamp glasses. As it frequently happens,
moreover, that the glass and ring do not fit together accurately an inlet of

page_text: foul air often takes places at that part. The ring is constantly liable to become
unscrewed by simply turning the glass from the outside, the friction of the
glass against the ring carrying it round with it.
Now according to my Invention I form an annular groove on the surface
of the ring and cause the glass to fit into such annular groove, and in order
to prevent the possibility of the ingress of foul air into the lamp at the top
and bottom of the glass, and to allow for expansion, I introduce at those parts
an elastic packing ring or washer of vulcanized india-rubber, and at the
bottom of the glass I interpose a metal ring or washer between the india-
rubber and the annular grooved ring, this metal washer being maintained in
its place by a projection thereon fitting into a hole or recess in the screwed
portion of the lamp; by this means the loosening of the securing ring by turning
the glass is prevented.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Evan Thomas in the Great Seal Patent Office on
the 20th May 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EVAN
THOMAS, of Aberdare, in the County of Glamorgan, Ironmonger and Safety
Lamp Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of November, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said Evan
Thomas, Her special license that I, the said Evan Thomas, my executors,
administrators, and assigns, or such others as I, the said Evan Thomas, my
executors, administrators, or 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 SAFETY LAMPS,"
upon the condition (amongst others) that I, the said Evan Thomas, my executors
or administrators, by an instrument in writing under my hand and seal, 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.

page_text: NOW KNOW YE, that I, the said Evan Thomas, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say:-
My said Invention has for its object the rendering the ordinary miners' safety
lamps more secure by the adoption of arrangements which prevent the glasses
from becoming loose and so preventing the entry of the foul gases in the
lamps.
According to the present ordinary construction of miners' safety lamps the
glass is held in the lamp by means of a plain or flat metal ring which fits into
a screw on the lower part of the frame of the lamp, and bears directly against
the bottom of the glass, no allowance being made for expansion of the glass,
and-hence the frequent fracture of lamp glasses. As it frequently happens
moreover that the glass and ring do not fit together accurately an inlet of
foul air often takes place at that part; the ring is constantly liable to become
unscrewed by simply turning the glass from the outside, the friction of the
glass against the ring carrying it round with it.
Now according to my 'Invention I form an annular groove on the surface
of the ring, and cause the glass to fit into such annular groove, and in order
to prevent the possibility of the ingress of foul air into the lamp at the top
and bottom of the glass, and to allow for expansion, I introduce at those parts
an elastic packing ring or washer of vulcanized india-rubber, and at the
bottom of the glass I interpose a loose metal ring or washer between the india-
rubber and the annular grooved ring; by this means the loosening of the
securing ring by turning the glass is prevented.
And in order that my said Invention may be fully understood I shall now
proceed more particularly to describe the same, and for that purpose shall
refer to the Figures on the annexed Sheet of Drawings, the same letters
of reference indicating corresponding parts in both the Figures.
Figure 1 of the Drawings represents a partial sectional elevation of an
ordinary miner's safety lamp with my improvements adapted thereto, and
Figure 2 is a plan of the lower ring, which supports the glass detached,
showing the elastic packing ring of india-rubber and the loose metal
washer.
A is the base of the lamp which is screwed into the rim or lower frame B,
but before screwing on the base there is screwed into the rim the annular
grooved securing ring C, such ring being screwed home till it bears against
the bottom of the glass. The annular groove or channel à formed on the
=

page_text: surface of the securing ring C contains, first, a metal washer b, and above
that again the elastic or vulcanised india-rubber packing ring c (shown clearly
in Figure 2), upon which the bottom of the glass D directly bears; both
these rings being loose or free to revolve on the surface of the securing ring C
the turning of the glass cannot effect the loosening of the securing ring. The
metal washer 6 is kept in the groove by the shoulder & screwed into the
centre of the grooved securing ring C, or by any other convenient contrivance.
The upper frame or rim E of the lamp is annularly grooved on its under
surface to correspond with the annular groove in the securing ring C, and it
is also provided with an elastic packing ring e, similar to the packing ring c
below, so that the upper as well as the lower ends of the glass bear directly
upon the elastic packing in lieu of upon the metal itself of the lamp.
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 herein-
before in part recited Letters Patent is,―
1st, the peculiar mode of fitting or securing the glasses of miners' safety
lamps, as herein-before described.
2nd, the application of the elastic packing rings, metal washer, and
annularly grooved securing ring for the purpose of allowing for expansion of
the glass, preventing the access of foul air to the lamp, and avoiding the
loosing of the securing ring by turning the glass, substantially as herǝin-
before described.
In witness whereof, I, the said Evan Thomas, have to this my Specifi-
cation hereunto set my hand and seal, this Sixteenth day of May, One
thousand eight hundred and sixty-seven.
EVAN THOMAS. (L.S.)