IMPROVE- MENTS IN ILLUMINATING GRATINGS FOR ROOFS AND FOOTWAYS
Year: 1871

page_text: LETTERS PATENT to Thaddeus Hyatt, of Gloucester Gardens, Hyde
Park, in the County of Middlesex, for the Invention of "IMPROVE-
MENTS IN ILLUMINATING GRATINGS FOR ROOFS AND FOOTWAYS."
Sealed the 31st October 1871, and dated the 10th August 1871.
PROVISIONAL SPECIFICATION left by the said Thaddeus Hyatt at the
Office of the Commissioners of Patents, with his Petition, on the
10th August, 1871..
I, THADDEUS HYATT, of Gloucester Gardens, Hyde Park, in the
County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN ILLUMINATING GRATINGS FOR ROOFS AND FOOTWAYS," to
be as follows:-
86
The illuminating gratings known in the United States of America as
Hyatt's lens lights," and recently introduced into England at the
Holborn viaduct and other places, consist of a cast-iron grating with
apertures less than two inches diameter, into which blocks or plugs of
glass are inserted, whose upper or exposed faces have an arched or
swelled form or cavity in order to shed dirt, collect a greater amount

page_text: walked upon.
As heretofore made this convexity or rise commenced invariably at the
edges of the glass, the diameter of the lens at its base being thus equal
to the diameter of the glass at its upper face; for example, suppose
the apertures or light holes in the grating to be 2 inches in diameter
in the clear above the seat on which the glass is to rest, the diameter
of the glass will then be about 1 ½ inches or an 18th less than the
aperture, so as to leave room for cement to make a water-tight joint
around it, and as the swell which forms the lens face commences at the
extreme edges of the glass the diameter of the lens at its base will thus
be 1½ inches. Now the height of the lens is limited by the height
of certain buttons or knobs of iron cast upon the surface of the grating,
which buttons are designed not only to give protection to the glasses,
but also to form a more safe surface for being walked upon in slippery
weather, but the height of these buttons is limited by their diameter,
and the diameter of these buttons is limited by the necessity of crowding
the light holes of the grating as near together as possible to secure the
greatest per-centage of light possible in every square foot of grating; it
therefore happens that these metallic buttons can rarely exceed half an
inch in diameter and frequently less than this, in general not more
ths of an inch, so that if these buttons were made under such circum-
stances more than a 1% or ths of an inch high an illuminating grating
would be produced covered with metal spurs, which would tend to trip
up the foot passengers, instead of a grating of greater safety to be
walked upon.
These are the conditions of an illuminating grating
which limit the convexity of the glasses; it therefore happens in
practice that the single lens-formed glasses heretofore made by me have
soon become scratched over a large proportion of their surfaces, because
of their too great flatness, the result being a material loss of light.
Hitherto my only remedy for this has been to reduce the diameter of
the glasses, but there are serious objections to any illuminating gratings
whose light holes are less than 1ths inches in the clear light space,
both as to increased weight of metal and diminished volume of light.
I subsequently proposed to remedy this defect by the use of larger
glasses, having their walking surfaces studded or covered with numerous
knobs or projections cast upon the face of the glass, but in cases of
fracture large openings would be left in the grating. I also proposed

page_text: to use a glass having a single knob or projection in the centre with
protecting knobs formed of metal or other material than glass sur-
rounding the single knob or lens, as will be seen on reference to my
Specification, No. 2755/70.
My present Invention relates partly to a mode of reconciling these
conflicting elements in constructing an illuminating grating having
single lenses only, and I accomplish the object by simply contracting
the diameter of each lens at its base where it springs from the face of
the glass block, so that the diameters of the two become unequal in
place of being equal, as heretofore. This inequality in diameters pro-
duces of necessity a flat space around the base of the lens upon the face
of the glass block, which block may be round, square, or. of any other
shape, but the purpose of the Invention is not to produce this flat space
upon the face of the glass block, it exists merely as an incident of the
Invention; the thing that is produced and is intended to be produced'
is a lens with rapidly sloping sides, and yet without contracting the
diameter of the glass block of which it forms the face or walking surface:"
By making a lens upon the flat face of a glass plug or blook in place of
making this face all lens I thus obtain the desired result, viz., an
illuminating grating with a safe walking surface, the iron buttons being
not too high with lens formed glasses presenting the minimum of
surface to be scratched, with glass blocks or plugs not vitiated by being
made too small, and an iron grating whose light spaces are properly
proportioned to secure the greatest economy in weight of metal con-
sistent with the greatest strength of material and the maximum volumn
of light or translucency.
My said Invention also relates to an improved mode of manufacturing
the metal plates or gratings intended to receive the improved glasses
herein-before referred to, although they may also be fitted with other
and well known forms of glasses, but I prefer to apply thereto the
improved glasses which constitute the first portion of this Invention.
I propose to manufacture small illuminating plates or quarries from
ordinary merchant sheets or plates of wrought iron or steel by first.
cutting up or subdividing the said sheets into pieces of the required
size and shape, and then placing each of these pieces under a press,
which punches or stamps therein the light holes. Where requisite
countersunk seats for the glasses may be stamped therein and projections
or buttons for better foothold raised upon the upper surface between the.
'

page_text: .
lights holes by countersinking from the under side. When stamped or
otherwise formed on steel plates I propose to increase the durability
of these buttons by casehardening them. I also turn down the edges
of the quarry all round in order to obtain the requisite depth for
strengthening the quarry and for forming a water-tight cemented joint
round it when fixing it into the main holding frame or supporting
grating, bolts and pins being thus dispensed with.
I further propose to produce rolled sheets of metal partially prepared
with a view to the manufacture therefrom of the illuminating quarries
above referred to. For this purpose a large plate or sheet is to be rolled
from a mass of metal in a heated state in any well known manner, the
rolls employed being provided respectively with corresponding pro-
jections and recesses working into each other for the purpose of de-
pressing or recessing the metal at those parts designed to receive the
glasses. The removal of the central part of this recessed or sunk portion
in order to form the light aperture may be effected either at the time of
rolling or by a subsequent punching operation. Solid knobs, projections;
or buttons are also to be rolled upon the upper surface of the plate
between the depressions or seats for the glasses by having suitable
recesses in the upper roll, which knobs may be casehardened, as before
mentioned. The recesses or depressions in the plate are disposed in
groups or clusters, sufficient plain metal being left round each cluster
to admit of the separation of the sheet into quarries or tiles, and to afford
sufficient metal to form the turned-down sides or edges of the same
with or without a bearing lip at the edge of the turned down portion
or sides, the same being produced after the sheet has been subdivided
into small pieces or quarries.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thaddeus Hyatt in the Great Seal Patent Office
: on the 10th February 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THADDEUS
HYATT, of Gloucester Gardens, Hyde Park, in the County of Middlesex,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of August, in the year

page_text: of our Lord One thousand eight hundred and seventy-one, in the
35th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Thaddeus Hyatt, Her special license
that I, the said Thaddeus Hyatt, my executors, administrators, and
assigns, or such others as I, the said Thaddeus Hyatt, my executors,
administrators, or 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
ILLUMINATING GRATINGS FOR ROOFS AND FOOTWAYS," upon the condition
(amongst others) that I, the said Thaddeus Hyatt, my executors or
administrators, by an instrument in writing under my hand and seal
should particularly describe and ascertain the nature of the said Inven-
tion, 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 Thaddeus Hyatt, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings,
and to the letters and figures marked thereon, that is to say:-
The illuminating gratings known in the United States of America as
"Hyatt's lens lights," and recently introduced into England at the
Holborn viaduct, in the City of London, and other places, consist of a
cast-iron grating with apertures less than two inches diameter, into
which blocks or plugs of glass are inserted, whose upper or exposed
faces have an arched or swelled form or convexity, in order to shed dirt
and present a less amount of surface to be scratched when walked upon.
As heretofore made this convexity or rise commenced invariably at
the edges of the glass, as shewn by the dotted line in Figure 1 of my
Drawings, the diameter of the lens at its base being thus equal to the
diameter of the glass at its upper face; for example, suppose the
apertures or light holes in the grating to be two inches in diameter in
the clear above the seat on which the glass is to rest, the diameter of
the glass will then be about one and seven-eighth inches, or one-eighth
less than the aperture, so as to leave room for cement to make a water-
tight joint around it, and as the swell which forms the lens face_com-

page_text: mences at the extreme edges of the glass the diameter of the lens at its
base will thus be one and seven-eighth inches. Now the height of the
lens is limited by the height of certain buttons or knobs of iron cast or
otherwise formed upon or secured to the surface of the grating, which
buttons are designed not only to give protection to the glasses, but also
to form a more safe surface for. being walked upon in slippery weather,
but the height of these buttons is limited by their diameter, and the
diameter of these buttons is limited by the necessity of crowding the
light holes of the grating as near together as possible to secure the
greatest per-centage of light possible in every square foot of grating;
it therefore happens that these metallic buttons can rarely exceed half.
an inch in diameter, and frequently less than this, in general not more
than three-eighths of an inch, so that if these buttons were made under
such circumstances more than a quarter or five-sixteenths of an inch
high an illuminating grating would be produced covered with metal
spurs, which would tend to trip up the foot passengers, instead of a
grating of greater safety to be walked upon. These are the conditions.
of an illuminating grating which limit the convexity of the glasses; it
therefore happens in practice that the single lens-formed glasses hereto-
fore made by me have after a time become scratched over a large pro-
portion of their surfaces, because of their too great flatness, the result
being a material loss of light. Hitherto my remedy for this has been
to reduce the diameter of the glasses, but there are serious objections
in some cases to any illuminating gratings whose light holes are less
than one and three-eighth inches in the clear light space, both as to
increased weight of metal and diminished volume of light. I sub-
sequently proposed to remedy this defect by the use of larger glasses,
having their walking surfaces studded or covered with numerous knobs
or projections cast upon the face of the glass, but in cases of fracture
a large opening would be left in the grating. I also proposed to use a
glass having a single knob or projection in the centre with projecting
knobs formed of metal or other material than glass surrounding the
single knob or lens, as will be seen on reference to my Specification,
No. 2755, in the year of our Lord One thousand eight hundred and

page_text: tracting the diameter of each lens at its base, where it springs from the
face of the glass block, so that the diameters of the two become unequal
in place of being equal, as heretofore. This is shewn clearly in full
lines in Figures 1 and 2 of the annexed Sheet of explanatory Drawings,
which represent respectively a lens composed of a segment of a sphere
and one composed of a hemisphere. The inequality in diameters above
referred to produces of necessity a flat space a, a, around the base of the
lens 6 upon the face of the glass block, which block may be round (as
shewn in my Drawing), square, or of any other shape, but the purpose
of the Invention is not to produce this flat space a upon the face of
the glass block; it exists merely as an incident of the Invention. The
thing that is produced and is intended to be produced is a lens with
rapidly sloping or steep sides, and yet without contracting the diameter
of the glass block of which it forms the face or walking surface. By
making a lens upon the flat face of a glass plug or block, in place of
making this face all lens, I thus obtain the desired result, vidclicit, an
illuminating grating with a safe walking surface, the iron buttons being
not too high with lens-formed glasses, presenting the minimum of
surface to be scratched with glass blocks or plugs not vitiated by being
made too small, and an iron grating whose light spaces are properly
proportioned to secure the greatest economy in weight of metal consistent
with the greatest strength of material and the maximum volume of
light or translucency.
When using a hemispherical lens light of the kind shown at Figure 2,
I prefer to substitute metal ribs running across the surface of the
grating between the rows of lens lights, for the buttons or protecting
knobs. herein-before referred to, as such buttons would have to be made
so high and slender as to be objectionable for the reasons already
stated.
My said Invention also relates to an improved mode of manufacturing
the metal plates or gratings intended to receive the improved glasses.
herein-before referred to, although they may also be fitted with other,
and well-known forms of glasses, but I prefer to apply thereto the.
improved glasses which constitute the first portion of this Invention.
The main object of this part of my Invention is to obtain illuminating.
quarries or gratings so thin as to obstruct the passage of the least
amount of light through the light apertures therein, whilst at the same
time a sufficient strength of metal is maintained..

page_text: b
I propose to manufacture small thin illuminating plates or quarries A,
one of which is shown in section and plan respectively at Figures 3
and 4) from ordinary merchant sheets or plates of wrought iron or steel,
by first cutting up or subdividing the said sheets into pieces of the
required size and shape, and then placing each of these pieces under a
press, which punches or stamps therein the light holes c.
Where re-
quisite countersunk seats d, d, for the glasses 6 may be stamped therein,
and projections or buttons e, e, for better foothold raised upon the upper
surface between the light holes by countersinking from the under side.
When stamped, rolled, or forged on steel plates I propose to increase
the durability of these buttons e by casehardening them. These buttons e
are more conveniently made hollow when rolled, but they may be made
solid when forged. I also turn down the edges f, f, of the quarry all
round in order to obtain the requisite depth for strengthening the quarry
and for forming a water-tight cemented joint round it when fixing it
into the main holding frame or supporting grating, a portion of which
aahon at a
a
I am thug enabled to dispense with the use of holts
b
I propose to manufacture small thin illuminating plates or quarries A,
one of which is shown in section and plan respectively at Figures 3
and 4) from ordinary merchant sheets or plates of wrought iron or steel,
by first cutting up or subdividing the said sheets into pieces of the
required size and shape, and then placing each of these pieces under a
press, which punches or stamps therein the light holes c.
Where re-
quisite countersunk seats d, d, for the glasses may be stamped therein,
and projections or buttons e, e, for better foothold raised upon the upper
surface between the light holes by countersinking from the under side.
When stamped, rolled, or forged on steel plates I propose to increase
the durability of these buttons e by casehardening them. These buttons e
are more conveniently made hollow when rolled, but they may be made
solid when forged. I also turn down the edges f, f, of the quarry all
round in order to obtain the requisite depth for strengthening the quarry
and for forming a water-tight cemented joint round it when fixing it
into the main holding frame or supporting grating, a portion of which
is shown at g, g. I am thus enabled to dispense with the use of holts
and pins.
I further propose to produce rolled sheets of metal partially prepared
(one of which is shown in section and plan respectively at Figures 5
and 6) with a view to the manufacture therefrom of the illuminating
quarries above referred to. For this purpose a large plate or sheet A
is to be rolled from a mass of metal in a heated state in any well
known manner, the rolls employed being provided respectively with
corresponding projections and recesses working into each other for the
purpose of depressing or recessing the metal at those parts designed to
receive the glasses, as shown at d, d, (Figures 5 and 6). The removal
of the central part of this recessed or sunk portion in order to form the
light aperture c may be effected either at the time of rolling or by a
subsequent punching operation. Knobs, projections, or buttons e, e, are
also to be rolled upon the upper surface of the plate A between the
depressions or seats d, d, by having suitable recesses in the upper roll,
which knobs may be casehardened, as before mentioned. The recesses
or depressions d, d, in the plate are disposed in groups or clusters, as
shewn clearly in Figure 6, sufficient plain metal being left round each
cluster to admit of the separation of the sheet into quarries or tiles, as
indicated by the dotted lines in Figure 6, and to afford sufficient metal
to form the turned down sides or edges f of the same with or without

page_text: a bearing lip at the edge of the turned down portion or sides, as shown
at h, h, in Figures 3 and 4, the same being produced after the sheet has
been subdivided into small pieces or quarries of a hexagonal or other
convenient form. If preferred the peculiar thin metal quarries herein-
before described and illustrated by Figures 3 and 4 may be produced
by casting in suitable moulds, and then annealing the casting, as is well
understood.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured
to me by the herein-before in part recited Letters Patent is,―
First. The peculiar form or construction of "lens lights" for illumi-
nating gratings, as and for the purposes herein-before described and
illustrated by my Drawings.
Secondly. The manufacture of illuminating metal quarries, wherein
all superfluous metal tending to obstruct the passage of light is removed,
whilst the requisite strength is maintained, as herein-before described
and illustrated by Figures 3 and 4 of my Drawings.
Thirdly. The manufacture of thin metal illuminating quarries with
edges turned down sufficiently deep to ensure a perfectly water-tight joint
being made with cement between the quarry and the grating in which
it is fitted, substantially as herein-before described and illustrated by
Figures 3 and 4 of my Drawings.
Fourthly. The preparation of metal sheets with a view to the manu-
facture therefrom of the before mentioned illuminating metal quarries,
substantially as herein-before described and illustrated by Figures 5
and 6 of my Drawings.
In witness whereof, I, the said Thaddeus Hyatt, have to this my
Specification set my hand and seal, the Tenth day of February,
One thousand eight hundred and seventy-two.
THADDEUS HYATT. (L.s.)