AN IMPROVEMENT IN THE CONSTRUCTION OF MINERS' SAFETY LAMPS
Year: 1869

page_text: LETTERS PATENT to Evan Thomas, of Number 7, Cardiff Street,
Aberdare, in the County of Glamorgan, Safety Lamp Manufac-
turer, for the Invention of "AN IMPROVEMENT IN THE CONSTRUCTION OF
MINERS' SAFETY LAMPS."
Scaled the 6th May 1870, and dated the 10th November 1869.
PROVISIONAL SPECIFICATION left by the said Evan Thomas at the
Office of the Commissioners of Patents, with his Petition, on the
10th November 1869.
I, EVAN THOMAS, of Number 7, Cardiff Street, Aberdare, in the
County of Glamorgan, Safety Lamp Manufacturer, do hereby declare
the nature of the said Invention for "AN IMPROVEMENT IN THE CONSTRUCTION
OF MINERS' SAFETY LAMPS," to be as follows:-
The Invention has for its object the rendering of the miners' safety
lamp more secure by the adoption of arrangements which exclude the
foul air or dust, and also prevent the formation of an explosive mixture
of gasses inside the lamp, and this I effect as follows:-
Firstly. In so constructing the lamp that the air which is required
for the purposes of combustion in the lamp is admitted by openings in

page_text: the cap on the top of the lamp and passes down to the wick or flame
through several wire gauzes.
Secondly. In fitting the glasses of the lamp perfectly air-tight by
means of elastic and metallic substances.
For these purposes I divide the lamp into two chambers running the
whole length of the lamp by means of inner tubes of glass or metal,
instead of the ordinary wire gauze, and between these tubes or chamber
I place a cone or division of wire gauze, and thus effectually prevent
any air passing into the lamp, except at the openings at the top of
the lamp, where it is admitted through a ring of wire gauze, after
which it is conveyed by perforations in an inner brass or metallic ring
downwards through the cone of wire gauze and several other divisions
of wire gauze placed between the chambers, and is thus admitted to the
wick of the lamp for combustion, the heated air escaping upwards
through the inner tube or chamber, and passing through a cap of wire
gauze placed at the top of such inner tube, and outwards through per-
forations made in the cap of the lamp. By thus admitting the air only
at the top of the lamp and conducting it downwards to the wick through
several divisions of wire gauze I effectually prevent foul or explosive
gas passing into the lamp, and also exclude dust or other particles
entering into the tubes. Moreover the air thus supplied enters the
lamp in a steady current, and by passing through the inner and outer
chambers formed by the tubes cools the upper portion of the lamp and
enables the wick to burn freely and supply a good light. The top of
the lamp is also permanently fixed by a bolt, which prevents the miner
removing the cap or top part of the lamp.
By another portion of my Invention I prevent the foul air entering
the lamp through the inequalities of the edges of the lower glasses
surrounding the flame, and this object I effect by placing in the groves
where the top and bottom edges of the glasses are inserted packing rings
or washers of an elastic substance with thin metallic rings or washers,
and by this means when the glasses are inserted and the lower part of
the lamp screwed on the glasses become fitted perfectly air-tight, and
no air can enter the lamp, except at the top part through the per-
forations made for that purpose, and it is also a means of preventing
the glasses from cracking by expansion when the lamp is burning.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Evan Thomas in the Great Seal Patent Office on
the 7th May 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EVAN
THOMAS, of Number 7, Cardiff Street, Aberdare, in the County of
Glamorgan, Safety Lamp Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of November, in the year
of our Lord Once thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Evan Thomas, Her special licence that I,
the said EvanThomas, my executors, administrators, and assigns, or such
others as I, the said Evan Thomas, 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 "AN IMPROVEMENT IN THE CONSTRUCTION OF
MINERS' SAFETY LAMPS," upon the condition (amongst others) that I, the
said Evan Thomas, 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 Evan Thomas, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement :-
This Invention has for its objects the rendering the miners' safety
lamp more secure by the adoption of arrangements which exclude foul
air or dust, and also prevent the formation of an explosive mixture of
gas inside the lamp, and this I effect as follows:-
Firstly. In so constructing the lamp that the air which is required
for the purposes of combustion in the lamp is admitted through openings.

page_text: in a perforated ring near the top of the lamp, and passes down to the
wick or flame through wire gauze.
Secondly. In fitting the glasses of the lamp perfectly air-tight by
means of clastic and metallic substances placed at the top and bottom
of the glasses.
For these purposes I divide the lamp into two chambers running the
whole length of the lamp by means of an inner and outer tube of glass or
metal instead of the ordinary wire gauze, and thus effectually prevent any
air passing into the lamp except at the openings at the top of the lamp,
where it is admitted through a ring of wire gauze or perforated metal,
after which it is. conveyed through perforations in an inner brass or
metallic ring (marked B on Drawing No. 1) downwards between the
outer and inner tubes through wire gauze placed at the bottom of the
inner tube, and thus admitted to the wick of the lamp for combustion
in the directions marked by the arrows shewn on the Drawing No. 1, the
heated air escaping upwards through the inner tube, and passing through
a cap of wire gauze, marked A on Drawing No. 1, and outwards through
perforations made in the cap of the lamp. By thus admitting the air
only at the top of the lamp and conducting it downwards to the wick
through wire gauze I effectually prevent explosion, the lamp, if burning,
immediately going out upon any gas passing into the tubes and reaching
the flame. This arrangement also excludes dust or other particles
entering into the inner tube; and moreover the air thus supplied enters
the lamp in a steady current, and by passing through the chambers
formed by the tubes it cools the inner portion of the lamp, and enables
the wick to burn freely and supply a good light. By making the per-
forations through the top of the cap, and marked E on Drawings
Numbers 1 and 2, I prevent the lamp going out when it is exposed to a
strong current of air in travelling at a rapid rate in being carried either
up or down the shaft or pit. In addition to the advantages already
named the danger of an explosion arising from the fracture of the outer
glass is entirely removed in consequence of there being an inner tube
or glass to protect the flame if the outer glass should accidentally
become broken, which is not unfrequently the case. The top of the
lamp is also permanently fixed by a bolt, marked C on Drawing No. 1,
and the cap is also fixed by a lock, marked F on Drawing No. 3, thus
preventing the miner removing the cap and obtaining access to the

page_text: flame without removing the bottom of the lamp, which is intended to
be locked.
By another portion of my Invention I prevent the foul air or gas
entering the lamp through the irregularities of the edges of the lower
glasses surrounding the flame, and this I effect by placing in the groves
where the top and bottom edes of the glasses are inserted packing rings
or washers of an clastic substance, marked D in Drawing No. 1, with
thin metallic rings or washers, and by this means when the glasses are
inserted and the lower part of the lamp screwed on the glasses become
fitted perfectly air-tight, and no air can enter the lamp except at the
top through the perforations made for that purpose. This arrange-
ment also prevents the glasses cracking from expansion when the lamp
is burning.
In witness whereof, I, the said Evan Thomas, have hereunto set my
hand and scal, this Twenty-third day of April, in the year of our
Lord One thousand eight hundred and seventy.
Signed, scaled, and delivered by
the said Evan Thomas, in
the presence of
R. ORTON GERY,
26, Cardiff Street,
Aberdare.
EVAN THOMAS. (L.S.)