IMPROVEMENTS IN LIGHT- TRANSMITTING GRATINGS FOR HORIZONTAL OR OTHER OPENINGS OF CELLARS. OR OTHER CHAMBERS
Year: 1877

page_text: LETTERS PATENT to Lachlan McBean, of Glasgow, in the County of Lanark,
North Britain, Merchant, for the Invention of "IMPROVEMENTS IN LIGHT-
TRANSMITTING GRATINGS FOR HORIZONTAL OR OTHER OPENINGS OF CELLARS.
OR OTHER CHAMBERS."
Sealed the 5th February 1878, and dated the 7th August 1877.
PROVISIONAL SPECIFICATION left by the said Lachlan M Bean at the
Office of the Commissioners of Patents on the 7th August 1877.
LACHLAN MCBEAN, of Glasgow, in the County of Lanark, North Britain, Merchant.
" IMPROVEMENTS IN LIGHT-TRANSMITTING GRATINGS FOR HORIZONTAL OR OTHER
OPENINGS OF CELLARS OR OTHER CHAMBERS."
This Invention relates to gratings for horizontal and other openings of cellars or
other chambers, and has for its objects to secure as full a transmission as possible of
light, and in particular directions, and to make the gratings of the necessary
strength in an economical manner, and so as not to obstruct the projection of the
light in the required directions on the inner sides of the gratings.
The improved gratings are made as usual of cast iron, and are formed with
rectangular openings in which blocks or pieces of glass are cemented or fitted. Each
glass block is formed with a flat upper or outer surface, whilst on its under or inner
side it is formed with a narrow flat surface, extending along each edge, and adapted
to the retaining check or recess formed in the opening of the iron grating to receive
and support the glass block. Within the bordering surface, on the under or inner
side, the glass block is made with two projecting ribs, placed parallel to each other.
One rib is convexly rounded or curved, and the other one is concavely curved on
the side next the convex rib, and projects further, whilst its outer side is nearly at
right angles to the upper or outer surface of the block. With the described shape
of the glass block light striking the upper or outer surface at right angles, or nearly
so, passes from the under or inner side most fully in directions inclined towards the
side on which the convex rib is placed. Thus if in a street cellar grating the glass
blocks are arranged with the ribs parallel to the street, and with the convex ribs

page_text: nearer the house, the light will be thrown inwards towards the inner part of the
cellar.
The glass blocks are by preference fixed so that their upper surfaces may be
flush, or nearly so, with the surfaces of the longitudinal and transverse bars of the
iron grating, so as not to present recesses for the lodgment of dirt, and so as to be
easily cleaned. The outer surfaces of the iron grating are however, by preference,
formed with projecting bits to prevent slipping on them.
The transverse bars of the iron grating, or those which are at right angles to the
ribs of the glass blocks, are made deeper than the longitudinal bars, the latter being
made with as little depth or thickness as is consistent with the requisite strength.
This conformation of the bars prevents the obstruction by the bars of the light
which is thrown in inclined directions, as this light passes between the transverse
bars, which are comparatively deep, and has only to cross the smaller longitudinal
bars, which scarcely interfere at all with it. The transverse bars are made with
their under or inner projecting parts in a curved form so as to be deeper at their
middles, and so as to have the most strength for the weight of metal composing
them.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Lachlan McBean in the Great Seal Patent Office on the 5th February
1878.
LACHLAN M BEAN, of Glasgow, in the County of Lanark, North Britain, Merchant.
"IMPROVEMENTS IN LIGHT-TRANSMITTING GRATINGS FOR HORIZONTAL OR OTHER
OPENINGS OF CELLARS OR OTHER CHAMBERS."
My said Invention relates to gratings for horizontal or other openings of cellars
or other chambers, and has for its objects to secure as full a transmission as possible
of light, and in particular directions, and to make the gratings of the necessary
strength in an economical manner, and so as not to obstruct the projection of the
light in the required directions on the inner sides of the gratings.
My improved gratings are made as usual of cast iron, and are formed with
openings in which blocks or pieces of glass are cemented or fitted. Each glass
block has on its under side two parallel ribs or projecting parts, one rib being
convexly rounded or curved, whilst the other rib is concavely curved on the side
next the convex rib, and projects further, its outer side being nearly at right angles
to the outer flat surface of the block.
The glass blocks are by preference fixed with their outer surfaces flusb, or nearly
so, with the longitudinal and transverse bars of the iron grating, so as not to
present recesses for the lodgment of dirt, and so as to be easily cleaned. The outer
surfaces of the iron grating are, by preference, formed with projecting points or
studs to prevent slipping on them..
The transverse bars of the grating, or those at right angles to the ribs of the
glass blocks, are made deeper than the longitudinal bars, the latter being made with
as little depth or thickness as is consistent with the requisite strength. This con-

page_text: formation of the bars prevents the obstruction by the bars of the light which is
thrown in inclined directions, as this light passes between the transverse or deeper
bars, and has only to cross the longitudinal or smaller bars, which scarcely interfere
at all with it. The transverse or deeper bars are made with their under or inner
projecting parts in a curved form, so as to be deeper at their middles, and so as to
have the most strength for the weight of metal composing them.
And in order that my said Invention, and the manner of performing the same
may be properly understood, I hereunto append a Sheet of explanatory Drawings,
to be herein-after referred to, and representing my improved grating and glass
blocks for the same. In these Drawings the same reference numerals are used to
mark the same or like parts wherever they are repeated.
Figure 1 on the accompanying Sheet of Drawings is an edge view, and Figure 2
is an inverted plan of one modification of my improved glass blocks for light-
transmitting gratings; and Figures 3 and 4 are corresponding views of another
modification.
Figure 5 is a vertical section showing the grating as applied to a cellar light in
an ordinary street footpath; and Figure 6 is a section of the grating as at right
angles to Figure 5.
The glass block 7, shown in Figures 1 and 2, is formed with a flat upper or outer
surface, whilst on its under or inner side it is formed with a narrow flat surface 8,
extending along each edge, and adapted to the retaining check or recess formed in
the opening of the iron grating to receive and support the glass block. Within the
flat bordering surface 8, on the under or inner side, the glass block is made with
two projecting ribs 9, 10, placed parallel to each other. One rib 9 is convexly
rounded or curved, and the other one 10 is concavely curved on the side next the
convex rib, and projects further, whilst its outer side is nearly at right angles to the
upper or outer surface of the block. With the described shape of the glass block 7
light striking the upper or outer surface at right angles, or nearly so, passes from
the under or inner side most fully in directions inclined towards the side on which
the convex rib is placed. Thus if in a street cellar grating, such as is shown in
Figure 5, the glass blocks 7 are arranged with the ribs 9, 10, parallel to the street,
and with the convex ribs nearer the house, the light will be thrown inwards
towards the inner part of the cellar, as indicated by the dotted lines in Figure 5.
The glass block 7, shown in Figures 3 and 4, differs from that shown in Figures
1 and 2, merely in having the ribs 9, 10, parallel to the shorter sides instead of to
the longer sides. The glass blocks 7 may be made square or of any other con-
venient form in plan view, provided that the shapes and arrangement of the ribs
9, 10, are retained, the openings in the iron grating being of course shaped to
correspond.
In the construction of the cast-iron grating 11 (Figures 5, 6,) the metal is dis-
tributed so as to give the necessary strength with the least possible obstruction of
that portion of the light, which on passing through is directed to one side. The
transverse bars 12, or those at right angles to the ribs 9, 10, of the glass blocks, are
made deeper than the longitudinal bars 13, or those parallel to the ribs 9, 10, the
latter bars 13 being made with as little depth or thickness as is consistent with the
requisite strength. As the light thrown laterally is bent in planes at right angles
to the ribs 9, 10, it passes parallel to and between the deeper bars 13, and is very
little interfered with by the smaller bars 12. The deeper bars 13 are also curved,
as shown, to obtain the greatest strength for their weight.
Having thus particularly described my said Invention, and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise details
herein described or delineated, but that what I believe to be novel and original, and
claim as the Invention secured to me by the herein-before in part recited Letters
Patent is,
1. The improved form of glass blocks for light-transmitting gratings, herein-before
described, and shown on the accompanying Drawings.

page_text: "
2. The making of the bars of light-transmitting gratings of greater and less depth
respectively, accordingly as they are parallel or at right angles to the planes in
which the light is made to deviate, substantially as herein-before described.
In witness whereof, I, the said "Lachlan McBean, have hereunto set my hand
and seal, this First day of February, in the year of our Lord One thousand
eight hundred and seventy-eight.
LACHLAN MºBEAN. (L.S.)