IMPROVEMENTS IN LAMP GLOBES OR GLASSES
Year: 1868

page_text: LETTERS PATENT to William Corden, of Daichet, in the County of
Bucks, Artist, for the Invention of "IMPROVEMENTS IN LAMP GLOBES
OR GLASSES."
Sealed the 20th April 1869, and dated the 7th November 1868.
PROVISIONAL SPECIFICATION left by the said William Corden at the
Office of the Commisioners of Patents, with his Petition, on the
7th November 1868.
1, WILLIAM CORDEN, of Datchet, in the County of Bucks, Artist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN LAMP GLOBES OR GLASSES," to be as follows:-
This Invention has for its object improvements in lamp globes or
glasses.
In order to concentrate the light from a burner, and also to prevent
the passage of heat whilst allowing the light to be freely transmitted,
I employ a double cup-like glass with a space between the two cups,
which I fill with water. The outer cup is approximately a portion of a
Price 8d.1

page_text: sphere, and the inner cup may also be of a similar form; or in some cases
I make it simply cone or funnel shaped. The interior of the inner cup I
prefer to mould with a chequered pattern upon it so that its inner surface
is composed of a series of small planes meeting at angles, or where the
cone or funnel shape is adopted I sometimes make it polygonal in trans-
verse section on the interior, whilst on the outer side it is circular. The
water filled into the space between the two cups becomes heated and
slowly evaporates, thereby moistening the air which in brightly lighted
rooms is frequently unpleasantly dry. The water may advantageously
be tinted with blue or other color to modify the quality of the light. Or
in place of water other liquid of greater refractive power or having other
desirable property may be used.
In some cases I close in the inner cup at the top with a semi-globular
cover to serve as a reflector; it has an aperture at the top for the escape
of the products of combustion.
In some cases I make lamp globes or glasses in the way which I have
:described for forming the inner cup dispensing with the outer cup
and water space, that is to say, 1 form the inner surface of the cup of
a series of small planes meeting at angles whilst the exterior is left
smooth.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Corden in the Great Seal Patent Office
on the 6th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, WILLIAM
CORDEN, of Datchet, in the County of Bucks, Artist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of November, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Corden, Her special licence that
I, the said William Corden, my executors, administrators, and assigns,
or such others as 1, the said William Corden, my executors, adminis-
trators, or assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term

page_text: 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 LAMP GLOBES OR GLASSES," upon the condition (amongst others) that
I, the said William Corden, 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 Oflice within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said William Corden, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:―
This Invention has for its object to so construct lamp globes and
glasses as to concentrate the light from a burner all around below the
level of the light, whilst at the same time the direct passage of heat is
arrested; also to afford facilities for making the light of any agreeable
color, and also to render the air of a room more agreeable by the
evaporation of water. For this purpose I employ a double cup-like
glass with a space between the two cups, which I fill with water. The
onter cup is approximately a portion of a sphere, and the inner cup may
also be of a similar form; or in some cases I make it simply cone or
funnel shaped.
The inner cup is by preference composed of a series
of plane or slightly concave surfaces rounded at the angles. The
water filled into the space between the two cups prevents the trans-
mission of heat downwards, and becomes slightly heated and slowly
evaporates, thereby moistening the air which in brightly lighted rooms
is frequently unpleasantly dry. The water may advantageously be
tinted with blue or other color to modify the quality of the light. Or
in place of water other liquid of greater refractive power or having other
desirable property may be used. I prefer to employ a solution of
sulphate of zinc.
In some cases I close in the inner cup at the top with a semi-globular
cover to serve as a reflector. It has an aperture at the top for the escape
of the products of combustion.

page_text: In some cases
make lamp globes or glasses in the way which I have
described for forming the inner cup, dispensing with the outer cup and
water space, that is to say, I form the inner surface of the cup of a series
of planes meeting at angles whilst the exterior is left convex.
In the Drawings hereunto annexed I have shown examples of lamp
glasses or globes constructed according to my Invention. Figures 1
and 2 show a vertical section and plan of a lamp glass or globe
suitable for a gas burner. a is the outer cup very similar in form to an
ordinary lamp glass or globe for a gas burner; b is the inner cup
composed of a series of plane surfaces rounded at the angles where the
planes meet one another. The bottom of the cup b is fitted by grinding
within the bottom of the outer cup. The space c between the two cups
is filled in with water or other liquid, which arrests the passage of heat,
but allows light to pass freely. Any suitable metal reflector with an
aperture at the top for the escape of the products of combustion may be
placed above the top of the lamp glass or globe to reflect the light down-
wards and cause it to pass through the glass.
Figure 3 of the Drawings shows a lamp glass or globe suitable for a
moderator lamp. The sides of the inner cup b of the glass or globe
shown in this Figure are curved to a radius of double the length of the
radius of the curve of the outer cup. In plan view the inner cup
would appear of the form of the inner cup shown at Figure 2. d is a
reflector covering over the top of the glass b. The reflector may either
be of metal or it may be of glass rendered semi-opaque by being
ground on the outside.
In witness whereof, I, the said William Corden, have hereunto
set my hand and seal, this Fourth day of May, in the year of
our Lord One thousand eight hundred and sixty-nine.
WILLIAM CORDEN.
(L.S.)