IMPROVEMENTS IN DIOPTRIC REPRACTORS
Year: 1853

page_text: LETTERS PATENT to William Boggett, of Saint Martin's Lane,
in the County of Middlesex, Gentleman, and George Brooks
Pettit, of Lisle Street, in the same County, Gas Engineer, for the
Turvantion of is Tren IV DIODERIC REDDING
Sealed the 9th December 1853, and dated the 20th June 1858.
PROVISIONAL SPECIFICATION left by the said William Boggett
and George Brooks Pettit at the Office of the Commissioners of
Patents, with their Petition, on the 20th June 1853.
We, WILLIAM BOGGETT, of Saint Martin's Lane, in the County of
Middlesex, Gentleman, and GEORGE BROOKS PETTIT, of Lisle Street,
in the same County, Gas Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN DIOPTRIC REPRACTORS" to be as
follows:-
This Invention comprises certain modifications of prismatic refrac-
tors, analogous in principle to arrangements of a similar character
patented by the said William Boggett and one George Holworthy
Palmer, 22 October 1851, whereby a portion of the rays of light
emitted by an argand burner were refracted horizontally in any given

page_text: direction by means of glass prisms placed in an upright position on
each side of the light.
It became apparent on observing the effect thus produced that the
rays of light could in like manner be thrown downwards, or in any
other direction, by a proper application of the same principle, and with
a view to test the correctness of this opinion we constructed a trian-
gular-shaped solid glass ring, the inner surface of which was perpendi-
cular, the bottom horizontal, and the outer side diagonal (such as
would be made by bending a triangular glass prism into the form of a
hoop). On placing this ring in such a position as to encircle the flame
of a candle or other light the rays were refracted downwards with great
intensity, thus confirming our anticipations. The above is substan-
tially what we now seek to protect by the present Patent, without,
however, confining ourselves to any particular form or arrangement of
lenses, our Invention having in view certain novel arrangements of
dioptric glasses to the refraction of light in any given direction.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Boggett and George Brooks Pettit in
the Great Seal Patent Office, on the 20th December 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we,
WILLIAM BOGGETT, of Saint Martin's Lane, in the County of Middle-
sex, Gentleman, and GEORGE BROOKS PETTIT, of Lisle Street, the
same County, Gas Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twentieth day of June, in the year of
our Lord One thousand eight hundred and fifty-three, in the seven-
teenth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said William Boggett and George Brooks
Pettit, Her special licence that we, the said William Boggett and
George Brooks Pettit, our executors, administrators, and assigns, or
such others as we, the said William Boggett and George Brooks
Pettit, our executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-

page_text: after 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 In-
vention for "IMPROVEMENTS IN DIOPTRIC REFRACTORS," upon the condition
(amongst others) that we, the said William Boggett and George Brooks
Pettit, or one of us, by an instrument in writing under our hands and
scals, or under the hand and seal of one of us, 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 we, the said William Boggett and George
Brooks Pettit, do hereby declare the nature of our said Invention, and
in what manner the same is to be performed, to be particularly de-
scribed and ascertained in and by the following statement thereof,
reference being had to the Drawings hereunto annexed, that is to say:
Our Invention consists in constructing angular refractors either of an
annular or other convenient shape, to be so placed with regard to gas
or other lights, and with the angles or sides so disposed and arranged,
as to refract the rays downwards, or at any angle required. The par-
ticular form and arrangement of our refractors are clearly shewn in the
Drawings hereunto annexed.
It is well known that light in passing through glass or other trans-
parent medium of greater density than air is refracted or bent. When,
for instance, a light is placed near a triangular glass prism, as at a,
Figure 1, a portion of the rays, instead of passing horizontally through
it to b, issues at right angles from the bottom at c. By altering the
position of the prism, as in Figure 2, the rays issue from it in the
direction of the arrow, the angles of incidence and refraction being
always equal; it follows from this, that one or a series of prisms pro-
perly placed with regard to the light will refract it in any required
direction. We find as a general rule, that the best effect is produced
when the sides of the prisms are in the proportion of about four on one
side to three on each of the others; for example, if the side b, Fig. 1, is
four inches, a, and c, should each be about three inches. Figure 3,

page_text: represents an efficient arrangement for the accomplishment of one part
of our Invention; it consists of a solid glass ring (shewn in section at
Figure 4). This ring, on being so placed by means of a suitable holder
as to encircle the flame of a gas or other light, causes a large
portion of the lateral rays to be thrown down with great intensity.
If the ring be inverted, as in Figure 5, the rays, will on the con-
trary, be directed upwards. The size we prefer for these rings, when
applied to ordinary argand gas burners, is about seven inches diameter.
The aperture in the middle being about 3 inches in diameter at
bottom, and 33 inches at top. For other purposes they may be made
larger or smaller as required, and of any shape, such as oval, &c.
In cases where the weight of a solid ring is objectionable several
modifications of it may be employed, one of which is shown (in ver-
tical section) at Figure 6, wherein a series of prisms or triangular
steps are combined together, and serve to produce a like effect.
These refractors may likewise be used for throwing the light in a
diagonal direction, as shown by the arrows in Figure 12; but in such
instances we prefer making them of an oval shape for the readier
admission of the chimney glass. Figure 6, is a modification of Figure
6, encircling the lower part of the light. Figure 6", is a modification of
Figure 6, serving also to refract the rays downwards. Figure 7, shews
how an additional ring may be advantageously employed where the flame
extends above the lower ring; but care should be taken that the angle of
incidence in the upper one be so disposed as to refract the rays outside of
that beneath it. Figure 8, represents another arrangement for the
refraction of light downwards. It is a sectional view of two glass con-
centric rings so placed as to receive the rays from a circular ring gas
burner in the manner before described. These prismatic glass rings
can be made, if necessary, in separate pieces, of any convenient size, so
as to be applicable for ring burners of any dimensions. They may also
be made of any shape, such as square, rectangular, &c., without limit as
to the number or size of the burners, taking care, however, that the
perpendicular sides of the prisms are so placed as to receive the light.
Figure 8, is a top view of a series of burners and prisms, arranged con-
centrically; the parts of these prisms can either be suspended horizon-

page_text: tally by their ends to a metal frame above, like the drops in a chande-
lier, or fitted to the frame itself. Figure 9, represents one half of a
refractor (such as is shewn in Figure 3,) placed in front of, but rather
above, a fish-tail burner, the other half being similarly placed on
the opposite side, as in Figure 9; the upper parts inclining outwards,
as shewn in cross section at Figure 9". This arrangement is more
particularly applicable to street lamps, a portion of the upward rays,
which are now useless, entering the prisms at a, and emerging at b,
(Figure 9,) are thus thrown down and made available, without inter-
cepting any portion of useful light. Segments of Figure 6, may be em-
ployed as in Figures 9, 9ª, and 9", with the like effect. These segments
can either be attached to a metal frame at bottom or suspended from
above. Figure 10, is a section of a series of double prisms a, a, with
single ones c, at the ends, having ring burners between them at b, with
upright jets of gas, the light from which entering and emerging from the
prisms in the direction shewn by the arrows forms a cheap and effec-
tive means of lighting churches and large rooms from above. Figure
10%, is a top view of the preceding arrangement; and Figure 10", a
section of the burners in Figure 10, in which a, a, a, a, are the burner
tubes receiving their supply of gas from above. Figure 11, represents a
chandelier constructed upon the principle of Figure 6". a, a, are ring
burners with upright jets, the light from which is thrown down in the
direction of the arrows; an argand burner b, may be inserted at bottom,
if required, the globe lights c, c, serving to illuminate the upper part of
the room, as well as for ornament.
It is not necessary that we should describe the moulds and plungers
(or the method of using them) employed in forming the various appa-
ratuses herein mentioned, the processes being well understood by glass
manufacturers. The material from which the refractors are to be made
should be as clear and pellucid as possible.
And having now described the nature of our said Invention, and the
manner in which the same is to be performed, we declare that we claim
the construction of triangular dioptric refractors of the forms herein-
before described, and so placed with respect to the light to be refracted
as to throw down or disperse the rays in the direction required, as

page_text: described.
In witness whereof, I, the said William Boggett, for myself, and
on behalf of George Brooks Pettit, have hereunto set my hand
and seal. this Nineteenth day of December, One thousand
eight hundred and fifty-three.
WILLIAM BOGGETT. (L.S.)