IMPROVEMENTS IN SAFETY LAMPS
Year: 1879

page_text: LETTERS PATENT to William Smethurst, of Bryan, near Wigan, in the County
of Lancaster, Colliery Proprietor, for the Invention of "IMPROVEMENTS IN
SAFETY LAMPS.”
Sealed the 4th June 1880, and dated the 5th December 1879.
PROVISIONAL SPECIFICATION left by the said William Sinethurst at the
Office of the Commissioners of Patents on the 5th December 1879.
WILLIAM SMETHURST, of Bryan, near Wigan, in the County of Lancaster, Collierý
Proprietor. "IMPROVEMENTS IN SAFETY LAMPS."
My Invention relates to improvements in safety lamps, whereby they are
rendered less liable to be damaged or put out of order and greater security against
explosion is obtained.
In carrying out my Invention I make the upper portion of the lamp in the form
of a cylindrical metal shield, and I either dispense with the wire gauze usually
employed or arrange the same inside the said shield. Air for supporting com-
bustion is supplied to the lamp through perforations round the seat of the lamp
and other perforations (which will not admit of the passage of flame) are provided
at the upper part of the metal shield for the escape of the products of combustion..
By the peculiar construction of the lamp the light will be extinguished in any
explosive mixture, and the presence of gas will be readily detected.
This Invention can readily be applied to all existing lamps (especially to the
Clanny, Davy, or Jack lamp) by the adaptation of the shield hereinbefore
referred to.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Smethurst in the Great Seal Patent Office on the 5th June
1880.
WILLIAM SMETHURST, of Bryan, near Wigan, in the County of Lancaster, Colliery
Proprietor. "IMPROVEMENTS IN SAFETY LAMPS."
My said Invention relates to improvements in safety lamps, whereby they are
rendered less liable to be damaged or put out of order and greater security against
explosion is obtained.
In carrying out my said Invention I make the upper portion of the lamp in the
form of a cylindrical metal shield, and 1 either dispense with the wire gauze
usually employed or arranged the same inside the said shield; air for supporting
combustion is supplied to the lamp through perforations situate around its seat,
and other perforations are provided at the upper part of the metal shield for the
escape of the products of combustion.
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 several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in both the Figures.
Figure 1 of the accompanying Drawing represents an elevation of a safety lamp
constructed according to my said Invention, and Figure 2 is a vertical section of
the same.
A is the cylindrical metal shield which forms the upper portion of the lamp, and
is provided with perforations a situate at its upper part and around the periphery
thereof for the escape of the products of combustion from the wick B, the said
perforations being such that the passage of flame therethrough is prevented.
Air for supporting combustion is supplied to the lamp through other perforations b
situate around the sent of the lamp.
In my improved lamp the usual wire gauze may be dispensed with, or it may
be arranged within the shield A, as shown at C, Figure 2.
In a safety lamp constructed according to this arrangement the light will be
extinguished in any explosive mixture, and the presence of gas may be readily
detected.
The hereinbefore described improvements can be readily applied to lamps as at
present constructed.
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 hereinbefore in part
recited Letters Patent is,-
The improvements in safety lamps, substantially as hereinbefore described and
illustrated in the accompanying Drawings.
In witness whereof, I, the said William Smethurst, have to this my Speci-
fication set my hand and seal, this Second day of June, One thousand eight
hundred and eighty.
WILLIAM SMETHURST. (L.S.)