İMPROVEMENTS IN APPLYING PRACTICALLY THE PRINCIPLE OF INTERNAL REFLECTION WITHIN TRANSPARENT SUBSTANCES
Year: 1856

page_text: LETTERS PATENT to Obed Blake, of the Thames Plate Glass Works,
Blackwall, in the County of Middlesex, Manager, for the Invention of
"İMPROVEMENTS IN APPLYING PRACTICALLY THE PRINCIPLE OF INTERNAL
REFLECTION WITHIN TRANSPARENT SUBSTANCES,"
Sealed. the 1st November 1856, and dated the 6th May 1856.
PROVISIONAL SPECIFICATION left by the said Obed Blake at the Office
of the Commissioners of Patents; with his Petition, on the 6th May
1856.
I, OBED BLAKE, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN APPLYING PRACTICALLY THE PRINCIPLE OF INTERNAL REFLECTION
WITHIN TRANSPARENT SUBSTANCES," to be as follows:-
In order to obtain the greatest possible amount of light for places which
would usually be dark, and where it is necessary, in obtaining light, to have in
view great strength in the illuminating medium, and such economy as will
permit the illuminators to be generally employed, I propose to make a frame
or frames of wood, iron, or any suitable metal or material; this frame will be
divided by thin partitions, of any number and of any material. Between these
partitions I fit or fix plates of glass, longitudinally and vertically, in such
manner as the edges of the plate shall be both upper and undermost, ensuring
the strength of the entire width of the plate of glass in addition to that of the
framing and partitions, forming, as it were, a solid block. Assuming one of
these blocks to be placed in a ship's deck, it would be found that the whole
amount oflight (when clear plate glass is used) would be given into the cabin
or hold below, and the partitions above mentioned would not in anywise
TD 17

page_text: obstruct or absorb, the rays of light obtainable. Where economy is more
particularly to be considered, I propose.to use rough or partially polished plate
or other glass. Carrying this principle of internal reflection further, I pro-
pose to make a parrallelogram of fine and pure glass, of dimensions suitable to
the number of reflections I wish to produce; to grind and polish this on all
its sides, taking care to preserve the angles clean and sharp. This mass of
glass, thus shaped and polished, and which I propose to term a designing
glass, may be used without mounting or additional apparatus. By simply
applying one end to or near an object, and placing the eye at the opposite end,
the object will appear so pictorially arranged as to form a multiplied pattern or
design; but although the instrument may be used without fittings, it will be
preferable to mount it, as thereby arrangements can be made for directing
light on to the objects, and also for securing a design while copying. The
instrument resembles the kaleidoscope, but will possess greater range, and as
the objects will be reflected parrallel to each other, and as any fabric or texture
may be used as a ground, the designer will be enabled to judge of the effect
of the pattern when worked up. The instrument may be made of such dimen-
sions that both eyes may be used, and the design made to appear as spreading
over several feet of space.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Obed Blake in the Great Seal Patent Office on the
6th November 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, OBED
BLAKE, of the Thames Plate Glass Works, Blackwall, in the County of
Middlesex, Manager, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of May, in the year of our Lord One
thousand eight hundred and fifty-six, in the nineteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Obed Blake, Her special licence that I, the said Obed Blake, my executors,
administrators, and assigns, or such others as I, the said Obed Blake, 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 "IMPROVEMENTS IN APPLYING PRACTICALLY THE
PRINCIPLE OF INTERNAL REFLECTION WITHIN TRANSPARENT SUBSTANCES," upon the

page_text: condition (amongst others) that I, the said Obed Blake, 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 Obed Blake, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being. had to the Sheet of Drawings hereunto annexed,
and forming part of this my Specification, and to the letters of reference
placed on the different Figures or Diagrams drawn thereon, such letters of
reference serving to denote similar parts where such parts appear or can be
seen at each of the Figures respectively:-
The nature of my improvements relates, in the first instance, to obtainingthe
greatest possible amount of light for places which would usually be dark, and
where it is necessary, in obtaining light, to keep in view great strength or
resisting power in the illuminating medium and its adjuncts, and such economy
in material as will permit the illuminators constructed under this Invention to.
be generally employed. I may term them grating illuminators, as they are, in
fact, gratings filled with glass,in the manner herein-after described. Assuming
one of these gratings to be inserted into a ship's deck, it will be found that the
light which enters the slips or slip of glass fixed edgewise in the openings of
the grating will pass through with no greater diminution than would occur in
a plate of polished glass of the thickness of the said grating, while the narrow-
ness of the glazed apertures, combined with the depth of the glass, and the
metal or other substance of which the divisions of the grating may be made,
gives strength so great that heavy weights may be thrown upon or be rolled or
dragged across the grating without injury thereto; and, further, while the
brilliancy of polished glass is retained, the slipperiness of surface is avoided by
means of the slightly raised edges of metal (or other substance) which form
the divisions between the pieces of glass. For the sake of economy I use the
waste cuttings (or cullett) of polished plate glass, and it will be observed that
the slight irregularity of the edges of such cuttings or slips, caused in cutting
by the glazier's diamond, are sufficient to prevent objects being distinctly visible
through the lights. When superior finish is required, the edges may be polished
and the same result obtained by rounding or bevilling the under edge of the
slip. And I would here remark, that in order to transmit the whole of the
light, it is necessary that the said slips should be polished or have a bright sur-

page_text: face on the sides or faces which are cemented to the divisions of the grating;
for if the sides be rough or emeried, such of the rays of light which have an
angular direction will as they reach such surface be lost by dispersion instead
of being reflected to the opposite surface, and thence by several reflections
transmitted to the bottom edge of the glass. The cement used should not
unite in optical contact with the glass; plaster of paris will not; and I prefer to
use that cement. The meaning of the term "optical contact" may be succintly
explained as follows:-Take a thick piece of polished plate glass with an
even bright edge, place it horizontally before the eye, and lay a piece of black
wax on the plane of the glass; on looking into the edge of the glass the wax
so loosely placed or laid on cannot be seen; but melt a portion of the wax and
drop it on the plane of the glass, and the portion of the glass so covered by the
melted wax will appear as a dark space, shewing that the light which reached
this covered space
has
passed away from the glass and become absorbed by the
wax. This first part of my Invention is illustrated in the annexed Drawing
by Diagrams 1, 2, 3, and 4.
The second part of my Invention or discovery is illustrated by Figures 5
and 6 of the Drawing, and carries the principle of internal reflection in a new
direction. I make a solid parallelogram of fine and pure glass of any dimen-
sion (such being governed by the size and number of reflections I desire to
produce), grind and polish this on all its sides and at both ends (the lower end,
or that applied to or near the object, may be slightly bevilled or made angular
if desired); this I term a designing glass, and its purpose is to show an object
or objects placed in contact with or near its end, so pictorially arranged as to
form a multiplied pattern or design. This instrument resembles the kaleido-
scope, but possesses greater range; the objects are reflected parallel to each
other, and as any fabric or texture can be used as a ground, the designer is
enabled to judge of the effect of the pattern when worked
up.
I will now proceed to describe the Drawing, on which it will be seen that
Figure 1 is a top plan view of a grating light, suitable for insertion into a
ship's deck, the floors of warehouses, the roofs of houses, or any place where
while light is desired, a great resisting power is also required. Figure 2 is a
longitudinal section taken through the line A, B, at Figure 1. Figure 3 is
a top plan view of a grating light to be let into the pavement of footpaths
and other places, to give light to vaults or cellars, shewing the light ready for
use; Figure 4 is a cross section through the line C, D, of Figure 3. Figure 5
is a side elevation of a designing or "object" glass. Figure 6, an end view of
the glass; and Figure 7, side view of a transparent object, all hereafter
- described.

page_text: At Figures 1 and 2 it will be observed that I make a framing a of iron,
wood, or other suitable metal or material (and they may be constructed either
with the divisions fixed or seperate, and then inserted and cemented in with
the glass; I prefer the latter method); I then take plates of glass band arrange
and secure them in the framing both longitudinally and vertically; the
divisions divisions c are arranged so as to admit one, two, or more plates of
glass between each of them. 1 secure the plates in position by fixing them with
plaster of paris, or any other suitable cementing material that does not unite in
"optical contact" with glass, and I so arrange that the upper edges of the plates
of glass, as they lie in the compartments or divisions of the framing, do not
come even with the upper surface or ribs of the grating, but allow it and them
to interpose between the glass and the foot of the passenger, or any substance
that may be wheeled or dragged over the grating light. It will be seen that
the framing and glass form, as it were, a solid block, (for whatever the depth
of the metallic or wooden grating bars, the glass portion is made as deep, with
the exception before mentioned,) which is let into the deck of a vessel or other
place, and secured in position by screws or bolts through the side and end
framing, or cemented or otherwise fastened therein. As the glass or plates or
glass are embedded or secured in divisions, a fracture of one or more in a
division or compartment is easily repaired without taking out the framing
namely, by punching out the broken glass and refilling the cavity.
Figures 3 and 4 areviews of a circular grating light constructed in precisely
the same manner as described in reference to Figures 1 and 2.
Figure 5, of a square glass d, or parallelogram, made of fine glass, with
sharp angles on all sides. This glass is capable of producing designs or patterns
alone, but for the purpose of securing or fixing a design er pattern when a
suitable one is obtained, I place it in a frame on a stand e, e, with a set screw f,
to keep the glass d stationary.
Figure 6 is an end view of the glass, shewing the frame through which it is
passed, and in which it can be turned round at pleasure, and mode of securing
it in position by set screw f.
Figure 7 represents a glass cell y fitted with a metallic cap hand tightening
screw i. Objects of any kind, such as silks, or other fabrics, colored or not.
glass or other substances, transparent or opaque flowers, or parts thereof,
being placed upon the plate of the cell (which is then fixed in position) will
form patterns or designs; or when design glasses of very large dimensionsare
used, the glass is supported by two pillars and works on an axle vertically;
the objects, flowers, or other are then placed upon a stage of suitable
elevation, and the lower end of the design glass brought to bear on them. The

page_text: operator or designer on looking through the reverse or upper end of the glass
discovers that the objects in the cell or in the stand (as the case may be) are
arranged, by reason of the internal reflection of the glass d, into a design, and
that such design is multiplied in parallels, as aforesaid. Should that produced,
not suit him, he adds or substracts something to or from the objects, or simply
disarranges them and looks again, or he moves the glass in its framing, and so
changes the pattern or design. When he is satisfied with the pattern produced
he turns the set screw/ so as to secure the glass in position, and proceeds to
take the design or pattern on paper or any other material. The glass dis
made, when desired, of such dimensions that both eyes may be used, and the
multipled design is thus made to appear as spreading over a considerbl>
space.
Having now described the nature of my discovery or Invention, and the
means by which I carry it into effect, I desire it to be understood that, in the
first part of my Invention, I do not confine myself to any particular size,
dimension, or form of grating lights, as they may vary to any extent, nor do 1
lay any claim to the exclusive use of any of the parts or articles used in their
construction when taken as parts and not in combination for the purposes of
my Invention; but I claim for and in respect of this part of my Invention, the
exclusive use of the combination of plates of glass with bright or polished
surfaces,secured in frames or framing constructed and arranged in the manner
herein-before described.
And as regards the second part of my improvements, being a discovery of a
novel application of the principle of internal reflection within transparent
substances, I claim the exclusive use of the solid parallelogram or piece of
glass for obtaining designs or patterns, as herein-before set forth and
described.
In witness whereof, I, the said Obed Blake, have hereunto affixed my
hands and seal, this Fourth day of November, in the year of our
Lord One thousand eight hundred and fifty-six.
JOHN GEDGE,
Patent Agent,
OBED BLAKE. (LS)
4, Wellington Street South, Strand.