AN IMPROVEMENT IN LAMPS FIXED IN STREETS, OPEN SPACES, FACTORIES, RAILWAY STATIONS, AND PUBLIC BUILDINGS.
Year: 1871

page_text: LETTERS PATENT to Thomas Alfred Skelton, of 37, Essex Street,
Strand, London, Architect, for the Invention of "AN IMPROVEMENT IN
LAMPS FIXED IN STREETS, OPEN SPACES, FACTORIES, RAILWAY STATIONS, AND
PUBLIC BUILDINGS.
"
Sealed the 11th August 1871, and dated the 25th April 1871.
PROVISIONAL SPECIFICATION left by the said Thomas Alfred Skelton
at the Office of the Commissioners of Patents, with his Petition,
on the 25th April 1871.
I, THOMAS ALFRED SKELTON, of 37, Essex Street, Strand, London,
Architect, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN LAMPS FIXED IN STREETS, OPEN SPACES, FACTORIES, RAILWAY
STATIONS, AND PUBLIC BUILDINGS," to be as follows:-
The application of glass prisms or prismoids, or of reflectors, or a
combination of them placed horizontally in front of the point of light,
that is, between and above the point of light and the place or space
into which the light is to be directed, so arranged that the rays of light

page_text: otherwise useless by reason of their upward direction may be reflected
or diverted into any required elevation.
This is proposed to be effected by this Invention in the manner shown
in the Drawing herewith deposited, in which A is gas or other burner;
B is the brightest point of light; O are prisms or prismoids, and D
position of reflectors, and by variations and combinations of the arrange-
ments therein described. The prisms, prismoids, or reflectors may be
within or outside the lamp casing, if any, and may be fixed in their
required positions and angles, or may each or all be capable of adjustment
to any required angle by means of screws or other simple mechanical
means and be easily removable for cleaning. The prisms or prismoids
may be of cast glass unpolished or polished on one or more or all sides,
and may be of clear transparent glass, or of colored glass. The reflectors
may be of "silvered" or "gilded" glass polished or silvered or gilded
metal, or other material having a reflecting surface. The reflecting
surfaces either of prisms, prismoids, or reflectors may be flat planes or
be made concave or convex as occasion may require. The prisms,
prismoids, or reflectors may be placed on one or more or all sides of
square or polygonal sided lamps, and may be formed in segments of
circles to partly or wholly surround the point of light in circular cased
lamps or open flames.
This Invention is intended to apply whether the illumination is by
gas or by other illuminating power, and the term "lamp" is intended to
include any point of light or flame whether enclosed in a glazed frame
or an unenclosed gas jet flame, or point of light, but it is not intended
or claimed to include light house, harbour, or other marine lights.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Alfred Skelton in the Great Seal Patent
Office on the 23rd September 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I; THOMAS 30
ALFRED SKELTON, of 37, Essex Street, Strand, London, Architect, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters -Patent, bearing date the Twenty-fifth day of April, in the year

page_text: of our Lord One thousand eight hundred and seventy-one, in the 34th
year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Alfred Skelton, Her special licence
that I, the said Thomas Alfred Skelton, my executors, administrators,
and assigns, or such others as I, the said Thomas Alfred Skelton, 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 LAMPS FIXED IN STREETS, OPEN SPACES, FACTORIES, RAILWAY STATIONS, AND
PUBLIC BUILDINGS," upon the condition (amongst others) that I, the said
Thomas Alfred Skelton, 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.
NOW KNOW YE, that I, the said Thomas Alfred Skolton, do hereby
declare the nature of my said Invention, and in what manner the samo
is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
This Invention consists in the application to certain lamps of reflectors
or glass prisms or prismoids or of a combination of reflectors, prisms, or
prismoids placed horizontally in front of the point of light and at such
angles with regard to the point of light according to the well-known
laws of the reflection and refraction of light as will intercept and utilize
by reflection or refraction certain rays of light otherwise useless by
reason either of their vertical elevation or direction, and in hermetically
or otherwise sufficiently enclosing such reflectors, prisms, or prismoids
between plates of glass, both as a protection from dust and moisture and
to economise labour in cleaning.
This improvement in lamps is specially applicable to street lamps and
other such lamps fixed in parks and open spaces, and in railway stations,
factories, buildings, and places where the rays of light ascending above
the level of the lamp are practically useless and wasted.
Having thus described the nature of my said Invention I will now
proceed to describe the manner in which I propose to carry the same

page_text: into effect, and for the purpose of more clearly describing the same,
I will use the Drawings hereunto annexed in each of the figures of
which the same letters of reference indicate similar parts, I wish
however it to be understood that I do not confine myself to the precise
details shewn in the said Drawings so long as the distinctive character-
istics of my Invention are adopted. I wish however here to state that
my Invention is applicable to lamps, such as I have above mentioned,
of any form or shape, and to such lamps, whether already constructed
and in use, as also to lamps of which this Invention or improvement
may hereafter form part of the original construction, and it may also
be applied to one or more sides of any such lamp.
"
The materials in which this improvement in lamps may be executed
are as follows:-The reflectors may be of any suitable material having
a reflecting surface. Thin "silvered glass" manufactured by a new
process and known as patent silvering," the glass being silvered by
a deposit of silver in solution, and not by the "quicksilver process," is
preferable, it being a brillant reflector unaffected by a high temparaturo
and protected by a red lead coating on the silvored side. The prisms
or prismoids should be of clear transparent glass and may be cast in
moulds of the required form and "fire glazed" or "cut" and polished
if the greatest effect is required and expence not an object. The
enclosing glass plates should be of flatted crown glass or of the 15 oz.
or 21 oz. sheet glass of the usual glazing quality, and where colored
illumination is required either or both of these plates may be colored
glass. The frame and fastenings should be of metal cast or stamped
or manufactured of sheet or rolled metal in the ordinary way for similar
metal cases to the required form, and if of iron then also tinned or
galvanised. The adjusting screws and appliances should be of metal.
The reficctors, prisms, prismoids, and glass plates may be fixed or secured
in red lead, putty, or in other similar cement; white lead and varnish
putty has the advantage of not discoloring.
Figure 1 represents the vertical section of an ordinary street lamp.
with cases of reflectors constructed according to my Invention taking
the place of part of the usual glazing (which is to be removed so far
as the cases extend), and in this application placed on two sides to
reflect the light in the direction of the length of the street. B represents
the highest point of light in the flame; C, C, are the otherwise useless
direct rays of light emanating from the flame which by this Invention I

page_text: divert and utilize; D, D, D, are the reflectors intercepting the above-
mentioned rays of light C, C; E, E, are the above mentioned rays
of light C, C, after reflection, by which they have been diverted into
a new direction; F, F, are the useful direct rays of light which are
not affected by this Invention. In this form of lamp of the usual
size it is advisable to let B, the flame or brightest point of light, be
about six inches from the bottom of the lamp frame, so that the under
side of the upper case may not be overheated or blackened by the
flame.
For ordinary street lamp purposes and to meet the necessities of
various positions requiring the light to be reflected to a greater or
less distance, or at greater or less angles it will be advisable to construct
these cases of reflectors upon a scale estimated to reflect at angles,
either of 65, 70, 75, 80, 85, and 90 degrees as shewn on Figure 2
and for intermediate or greater or less angles where specially required.
In Figure 2 I have represented a series of street lamps placed on
ground of different degrees of slope for the purposes of illustrating
These angles
the necessity of varying the angles of the reflectors.
must vary with the distance of the lamps apart from each other.
A simple method of ascertaining with practically sufficient accuracy
the position in which to fix each separate reflector is described in
Figure 3, in which the outlines of the lamp are represented by dotted
lines. B represents the point of light; B, O, the line or direction of
the highest ray of light intended to be reflected: P, Q, the angle at
which it is required to reflect the light; G, G, G, G, the position of the
intended enclosing glass plates. Then at "a" the point of intersection
of the lines B, O, and P, Q, set off any equal distance on those lines in
the direction of B and Q, and a line drawn through those points,
say "c" and "b," will be parallel to the required angle of the re-
flector D, which is to be placed in this position. Next draw a line
from B to "g" the outer edge of the reflector and the point "d” where
that line intersects the inner glass plate will be the position of the
inner edge of the next reflector, then set off as before equal distances on
the line of the ray of light B, d, and on the angle of reflection re-
quired d, f, and drawing a line through the points e, f, place the second
reflector parallel to the line e, f, and proceed as before. For angles of
greater inclination downwards from the lamp proceed as indicated
at h. h. Figure 3.

page_text: The angle of inclination at which the roof case A, Figure 1, should
be constructed so as to secure the maximum effect of reflection should
approximate to a line at right angles with the plane of the centre
reflecting surface in the upper or roof case A, as in Figure 1.
A mode of construction suitable for ordinary street lamps is explained
in detail in the Drawings on Sheet No. 1, Figure 4 representing a
vertical section of the upper case A; Figure 5 represents a horizontal
longitudinal section of the same, and Figure 6 a front exterior view or
elevation of the same case; Figure 7 shews a vertical section of the
side case A, a; Figure 8 represents a horizontal or longitudinal section
of the same and Figure 9 a front exterior view or elevation of the same
case, to all of which figures the following letters and references apply:-
`D, D, D, are the reflectors; G, G, G, the enclosing sheets of glass;
H, H., the metal frame; 1, I, I, I, the groves in the interior sides of the
metal case to receive the ends of the reflectors; J, J, J, J, the joint of
red lead or other suitable material to render the case airtight and
exclude dust or moisture; K, K, the pins or screws to secure the sheets
of glass in their places; L, L, the part of the lamp frame to which the
case may be fixed by clip Y or wedge or pin and loop M, or by screws
or other suitable means; M, M, the wedge or pin and loop; N, the
glass fitted to the lower part of the side of the lamp in the usual way;
Y, Y, copper clips rivetted to lamp frame and bent over the flange Z of
the cases to secure them in position; and Z flange part of case, by
which it may be secured to lamp frame, and which will also allow or
compensate for variations in size of lamp frames.
The vertical concentration or dispersion of the rays of light reflected
may be accomplished either by arranging each separate reflector to
reflect at an angle of inclination varying from the others or dispersion
by forming all the reflectors with surfaces slightly concave, convex,
or fluted in a horizontal direction, as shewn in Figure 10, a trans-
verse section of a concave silvered glass reflector; Figure 11 a transverse
section of a convex silvered glass reflector; and Figure 12 a transverse
section of a fluted or corrugated silver glass reflector; or dispersion
may be effected by forming one or both of the enclosing glass plates G
of clear fluted glass with the flutings put in a horizontal direction.
The horizontal dispersion of the light reflected may be usefully
employed where the lamp is required to give light in all directions, as
in lamps fixed at cross roads and in open spaces, and this dispersion may

page_text: be effected by forming cach reflector with a vertically fluted surface, as
in Figure 13, a longitudinal section of a single silvered glass reflector,
and in Figure 14 a horizontal section through the lamp D being the
fluted reflector, or by forming one or both of the enclosing glass plates G
of clear fluted glass, the fluting placed vertically.
The herein-before contained details, illustrations, and examples of this
Invention have related exclusively to lamps, in which the separate
reflectors are fixed and immoveable in their respective positions in their
several enclosing cases.
It may be found useful or necessary to construct lamps in such a
manner that each set of reflectors may be from time to time capable
of adjustment to any required angle as illustrated at Figs. 27 and 28,
and in which it may also be convenient to have the power to vertically
concentrate or disperse the rays of reflected light.
move.
Figures 15, 16, and 17 illustrate an efficient arrangement for these
purposes. Let each separate reflector D be fitted with a socket and
pivot R at each end (or be drilled to receive the pivots), let the sockets
at one side be drilled to receive the pins S, the head of the pin S to be
formed with a screw thread or female screw to correspond with the
adjusting screw U, let the metal frame I have the sides formed with
steps at right angles to the reflectors as at T, and each step be drilled
or cut to form a slot or socket in which the pivot R may be placed and
Let U be the adjusting screw formed with a thread reversed in
its direction at the centre point V, that is to say, one portion of the
screw U having a right-handed thread and the remainder a left-handed
thread, let one end of this screw be fitted with a milled head and be
secured by collars to a screw socket W, let the socket W be screwed
into the frame H, then having put all the respective parts together as
described by turning the screw socket W, the whole of the upper edges
of the reflectors D may be moved forwards or backwards and so change
their angle of reflection, and by turning the adjusting screw U the upper
edges of the reflectors D may be concentrated towards or extended from
the centre point V as the upper edges of the reflectors D will at each
revolution of the screw U move through different spaces according to the
position of the pivots R upon which they revolve, the position of the
pivots being graduated as shewn on Figure 17.
This Invention may be applied to lamps whose enclosing sides or tops
are globular, circular, or curved in form by using prisms or prismoids

page_text: •
Dd, and X or curved metal reflectors D of the required shapes and
curves enclosed between curved glasses as shewn in Figures 18 and 19,
or by constructing the cases with curved glass on the exterior and flat
glass towards the light, as shewn in Figure 20, in which case flat
reflectors may be used in the manner herein-before described for ordinary
street lamps, as shewn in Figures 20, 21, and 22, as they also may in
lamps whose tops are square or angular on plan, but of curved glass
in the vertical section, as described in Figures 23, 24, 25, and 26. The
same or similar mechanical construction of the enclosing cases and
fittings will apply to these curved forms of lamps with sockets in the
frame H of a proper form to receive the ends of the prisms or prismoids
instead of the grooves applicable to reficctors.
For indoor or factory purposes or other such employment of light,
these cases of reflectors may be fitted to utilize the otherwise wasted
rays of light without the necessity for any lamp casing, it being only 1
necessary to suspend or fix the cases of reflectors above the light in the
position for which they are to be constructed.
Prisms or prismoids of glass may be employed in all cases instead of
reflectors if desired, it being necessary to place one side of the prism
or prismoid at the same position and angle as the reflecting surface
would have occupied as D d in Figure 18. A continuation of reflectors
or prisms. or prismoids used to reflect light, and prisms or prismoids
placed so as to refract light may be employed where it is desired, also
to utilize the rays of light whose direction differs only slightly from the
direction in which it is required to divert them, as shewn in Figure 18,
where X represents a prism or prismoid diverting the light by refraction
and D a, prisms or prismoids diverting light by reflection.
2
An additional saving of light may be effected by causing the surfaces
of the metal enclosing cases, the backs of the reflectors, and the interior
surfaces of the lamp framework to be white, these surfaces being 3
illuminated by the flame will be reflected at various angles by the
reflectors.
And now having described the nature of the said Invention and the
manner in which it is to be effected and performed, I declare that what
I claim as my Invention and wish to be secured to me by the herein- 3
before in part recited Letters Patent is, the manufacture, application,
and use for the purposes herein-before mentioned of reflectors or glass
prisms or prismoids, or of a combination of reflectors, prisms or prismoids,

page_text: hermetically or otherwise sufficiently enclosed between plates of glass
as herein-before described and represented on the several Drawings
hereunto annexed.
In witness whereof, I, the said Thomas Alfred Skelton, have here-
unto set my hand and seal, this Twenty-third day of August One
thousand eight hundred and seventy-one.
T. A. SKELTON. (L.S.)