Improvements in or in connection with Traps and Ventilators for Drains.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in or in connection with Traps and Ventilators
for Drains.
I, EDWARD ALBERT GREEN, of Rock Street, in the City and County of Sheffield,
Chief Building Surveyor to the City Urban Authority, do hereby declare the
nature of this invention to be as follows:-
This invention relates to improvements in the design and construction of traps
and ventilators for drains, to render them suitable for fixing in the outer walls
of buildings close to public pavements; and whereby connection, disconnection,
ventilation, inspection and access are more readily, compactly and completely
provided for or secured.
My invention in the first place relates to an improved wall trap for drainage
purposes, whereby the flushing effect is rendered more efficient; and to the
combination therewith of provision for ventilation, whereby the downfall pipes
leading thereto are properly ventilated, and suitable provision is made for access
and inspection.
In the following description, reference is first had, to a combined wall trap
and ventilator in which the outlet is arranged laterally, and immediately after
the modifications required to adapt it for a vertical outlet will be described.
The body of the trap is made square or approximately square in horizontal
section, and rectangular in vertical section in the upper part; and of a width
say 9 to 10 inches from back to front to suit the width say 9 to 10 inches of the
wall, within which it is to be built. In the lower portion at the front side a bend
is formed to provide a lateral spigot outlet to fit in the socket end of the first of
the outfall pipes. The back wall of the trap box continues vertically to the well
at the bottom, where the box is narrowed so as to give a small exposed water
surface for evaporation or other emanations from the water in the well, and to
ensure the more efficient flushing of the well. This narrowing is effected by
giving the bottom part of the front wall a considerable inclination, the upper
end joining the lower surface of the before mentioned lateral outlet bend, the
junction forming a lip sufficiently high above the bottom of the midriff, (to be
immediately referred to), to form the water seal of the trap.
The interior of the trap box is divided by an inclined midriff into a rear re-
ceiving chamber, with small exposed water surface for evaporation and emana-
tion, and a front inspection and clearing chamber; the space between the upper
part of the midriff and the part of the front wall opposite it forming an access
opening, which is closed by a tripple stopper consisting of two cover plates and
a clay seal between and around them. The lower cover plate is supported by a
ledge formed on the front side of and about one half of the depth of the midriff,
and on the inner side of the front wall, and also along the sides of the trap to
form an oval access opening. This stopper is both easily applied and removed,
for inspection and access through the front chamber to the well of the trap, and

page_text: to the spigot outlet branch of the trap, for clearing away cement from the joint
of the first outfall pipe when fixing, and down through which a bamboo or other
drain rod may be pushed, to clear the outfall drain if blocked.
The midriff is not quite one half the full interior depth of the body of the trap,
so the front and rear chambers not only open into one at the bottom, but for a
considerable depth at the top. In this portion a rectangular ventilating opening
is formed in the front wall of the trap; the trap being built in
the wall at such a height that, the bottom of this ventilating
opening is slightly above the pavement or ground level; and as the outside of
the front wall of the trap is flush- with the outside of the wall in which it is built,
tne spigot outlet is only a short distance down and under the pavement. A
ventilating grid-iron is fitted in this opening; and may be arranged to be hinged
at its upper end to a bolt having its ends let into 'the sides of the body of the
trap, so as to swing inwards and upwards to give access to the interior of the
trap; or the ventilating grid may be arranged to be dropped into or slid down
vertical grooves formed in the inner sides of projecting rolls or a bead, formed
round the sides and bottom on the outer side of the ventilating opening. A bolt
or wooden plug projecting through the upper part of the ventilating grid, so as
to catch beneath the top of the ventilating opening, is provided to prevent the
mischievous lifting or removal of the grid. Or the side grooves may be made
wider at the top immediately below the underside of the top of the ventilating
opening, so that the grid on being dropped down can be pushed back flush with
the front of the top of the ventilating opening, and secured in place by filling
the wedge shaped spaces left in the grooves with a cement or wooden stopping
or wedge, which when raked or chipped out liberates the grate for removal.
Lugs are formed in the angles of the rear receiving chamber of the trap above
the trapped water line, upon which a horizontal wire screen is placed to intercept
all solid matter not fit to pass into the well or drain.
The drainage from baths, lavatories and sinks is brought and delivered into the
trap by an internal waste pipe the lower end of which goes through a circular
dovetailed perforation formed through the top of the trap inside one of its rear
angles. A cement joint is made between the outside of the waste pipe and the
periphery of the perforation to make an airtight connection, and prevent smell
escaping from the trap into the building.
The internal drainage brought by the bath, lavatory and sink pipes, and the
roof water is delivered from the external fall pipe into the trap by the waste
pipe, the lower end or connection of which is supported and fitted with a cement
joint in a recess or ledge, formed on the upper side round a circular perforation
or opening, formed through the top of the trap inside one of its rear angles. The
cement joint makes an airtight connection, preventing any smell from the interior
of the trap getting into the building. The position of the circular openings, as
just mentioned, is immediately over the rear receiving chamber, and thus facili-
tates the proper flushing of the well.
The connection of the lower end of the waste pipe to the trap is made by a
specially formed trumpet shaped bend, the lower end of which is fitted in the
circular opening in the top of the trap, as just above described. The other end
of the bend is fixed so that its face is vertical and flush with the outer face of the
wall, to receive the end of a second bend, forming the lower outlet end of the
fall pipe. An S bend may be employed in place of the two bends just men-
tioned. All the drainage is thus thrown downwards and directly into the rear
receiving chamber of the trap, causing it to be constantly and efficiently flushed,
and kept from becoming offensive; since the quantity of water held in the trap
is small, and cannot become stagnant.
As the lower part of the body of the trap is narrowed, as above mentioned, 1
make provision by means of a central rib on the outside of the front wall for
securing a level surface on the bottom of the trap, of the full width of the wall
in which the trap is built.

page_text: Where the outlet of the trap requires to be vertical, I make the body of the
trap wider at the lower than at the upper part; thus for example the lower
part may be conveniently made 12 inches wide, and rest on a 14 inch wall; and
the upper part 10 inches wide, the wall above it being 10 inches thick. The
front wall of the trap is vertical from top to bottom, but the back wall is vertical
at the top and at the bottom; these portions being connected by an inclined
or sloping portion. The spigot outlet is formed in the centre of the bottom,
and communicates, by an inclined passage formed by an inclined cross rib rising
from the bottom towards the front wall, with a front clearing chamber. This
inclined rib is continued sufficiently high, so that its top forms the lip of the
water seal. The space between this inclined rib and the lower vertical part of
the back wall forms the well of the trap. An inclined midriff, with its lower
portion dipping into the well, divides the middle part (considered vertically) of
the trap portion into a rear receiving chamber, with small exposed water sur-
face, and a front inspection and clearing chamber; which latter is closed at the
top in the manner already above described. Also, as in the trap first described,
a ventilating opening and dropped or hinged ventilating grate or grid are pro-
vided in the upper part of the front wall above the inspection and clearing
chamber.
My invention in the second place refers to an improved form of wall box venti-
lator for drains, similar to the upper box portion of the drain traps above de-
scribed; so as to enable such ventilators to be fixed in outside walls close to
public footpaths to give ventilation and access to drains. The box is made with
a circular perforation through its bottom, to admit of the end of a drain pipe, or
pipe connecting to the drain; said end standing a short distance above the
bottom of the box, and around which liquid cement is poured to form, when set,
an airtight joint.
If the drain pipe is not in the line of the wall, but to the outside of the wall,
a lateral rectangular opening is formed in the lower part of the front or outside
wall of the box. In front of this opening, and beneath and with its upper edge
flush with the top of the pavement or road level is placed an access frame, fitted
with a sliding cover plate; said plate having inclined or dovetail edges sliding
in similarly shaped grooves at the top of the sides of the frame; so that whilst
it can be slid back into the interior of the wall box to give access for rodding,
it cannot be mischievously removed; and by means of a plug or bolt, provision
is made to prevent it being similarly left open. Lugs on the frame and box and
bolts are provided for bolting the access frame to the ventilating box.
An open-
ing is provided in the bottom of the access frame or box for the upper end of the
drain pipe or pipe connecting to the drain. The ventilating box may be formed
either with a bottom or a lateral opening, or both; in which latter case, the
opening not used, is hermetically closed. The ventilating grid may be fixed and
secured in either of the ways referred to in the above description of the wall
traps.
Dated this 5th day of December 1800
J. CLARK JEFFERSON,
30, Park Row, Leeds, Agent for Applicant.
COMPLETE SPECIFICATION.
Improvements in or in connection with Traps and Ventilators
for Drains.
I, EDWARD ALBERT GREEN, of Rock Street, in the City and County of Sheffield,
Chief Building Surveyor to the City Urban Authority, do hereby declare the

page_text: nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
This invention relates to improvements in the design and construction of traps
and ventilators for drains, to render them suitable for fixing in the outer walls
of buildings close to public pavements; and whereby connection, disconnection,
ventilation, inspection and access are more readily, compactly and completely
provided for or secured.
My invention in the first place relates to an improved wall trap for drainage
purposes, whereby the flushing effect is rendered more efficient; and to the
combination therewith of provision for ventilation, whereby the downfall pipes
leading thereto are properly ventilated, and suitable provision is made for access
and inspection.
In the following description, reference is first had, to a combined wall trap
and ventilator in which the outlet is arranged laterally, and immediately after
the modifications required to adapt it for a vertical outlet will be described.
The body of the trap is made square or approximately square in horizontal
section, and rectangular in vertical section in the upper part; and of a width
say 9 to 10 inches from back to front to suit the width say 9 to 10 inches of the
wall, within which it is to be built. In the lower portion at the front side a bend
is formed to provide a lateral spigot outlet to fit in the socket end of the first of
the outfall pipes. The back wall of the trap box continues vertically to the well
at the bottom, where the box is narrowed so as to give a small exposed water
surface for evaporation or other emanations from the water in the well, and to
ensure the more efficient flushing of the well. This narrowing is effected by
giving the bottom part of the front wall a considerable inclination, the upper
end joining the lower surface of the before mentioned lateral outlet bend, the
junction forming a lip sufficiently high above the bottom of the midriff, (to be
immediately referred to), to form the water seal of the trap.
The interior of the trap box is divided by an inclined midriff into a rear re-
ceiving chamber, with small exposed water surface for evaporation and emana-
tion, and a front inspection and clearing chamber; the space between the upper
part of the midriff and the part of the front wall opposite it forming an access
opening, which is closed by a triple stopper consisting of two cover plates and
a clay seal between and around them. The lower cover plate is supported by a
ledge formed on the front side of and at about one half of the depth of the midriff,
and on the inner side of the front wall, and also along. the sides of the trap to
form an oval access opening. This stopper is both easily applied and removed,
for inspection and access through the front chamber to the well of the trap, and
to the spigot outlet branch of the trap, for clearing away cement from the joint
of the first outfall pipe when fixing, and down through which a bamboo or other
drain rod may be pushed, to clear the outfall drain if blocked.
The midriff is not quite one half the full interior depth of the body of the trap,
so the front and rear chambers not only open into one at the bottom, but for a
considerable depth at the top. In this portion a rectangular ventilating opening
is formed in the front wall of the trap; the trap being built in
the wall at such a height, that the bottom of this ventilating
opening is slightly above the pavement or ground level; and as the outside of
the front wall of the trap is flush with the outside of the wall in which it is built,
the spigot outlet is only a short distance down and under the pavement. A
ventilating grid-iron is fitted in this opening; and may be arranged to be hinged
'at its upper end to a bolt having its ends let into the sides of the body of the
trap, so as to swing inwards and upwards to give access to the interior of the
trap; or the ventilating grid may be arranged to be dropped into or slid down
vertical grooves formed in the inner sides of projecting rolls or a head, formed
round the sides and bottom on the outer side of the ventilating opening. A bolt
or wooden plug projecting through the upper part of the ventilating grid, so as

page_text: to catch beneath the top of the ventilating opening, is provided to prevent the
mischievous lifting or removal of the grid. Or the side grooves may be made
wider at the top immediately below the underside of the top of the ventilating
opening, so that the grid on being dropped down can be pushed back flush with
the front of the top of the ventilating opening, and secured in place by filling
the wedge shaped spaces left in the grooves with a cement or wooden stopping
or wedge, which when raked or chipped out liberates the grate for removal.
Lugs are formed in the angles of the rear receiving chamber of the trap above
the trapped water line, upon which a horizontal wire screen is placed to intercept
all solid matter not fit to pass into the well or drain.
The drainage from baths, lavatories and sinks is brought and delivered into the
trap by an internal waste pipe, the lower end of which goes through a circular
dovetailed perforation formed through the top of the trap inside one of its rear
angles. A cement joint is made between the outside of the waste pipe and the
periphery of the perforation to make an airtight connection, and prevent smell
escaping from the trap into the building.
.
The internal drainage brought by the bath, lavatory and sink pipes, and the
roof water from the external fall pipe is delivered into the trap by a waste
pipe, the lower end or connection of which is supported and fitted with a cement
joint in a recess or ledge, formed on the upper side round a circular perforation
or opening, formed through the top of the trap inside one of its rear angles. The
cement joint makes an airtight connection, preventing any smell from the interior
of the trap getting into the building. The position of the circular openings, as
just mentioned, is immediately over the rear receiving chamber, and thus facili-
tates the proper flushing of the well.
The connection of the lower end of the fall pipe to the trap is made by a
specially formed trumpet shaped bend, the lower end of which is fitted in the
circular opening in the top of the trap, as just above described. The other end
of the bend is fixed so that its face is vertical and flush with the outer face of the
wall, to receive the end of a second bend, forming the lower outlet end of the
fall pipe. An S bend may be employed in place of the two bends just men-
tioned. All the drainage is thus thrown downwards and directly into the rear
receiving chamber of the trap, causing it to be constantly and efficiently flushed,
and kept from becoming offensive; since the quantity of water held in the trap
is small, and cannot become stagnant.
As the lower part of the body of the trap is narrowed, as above mentioned, I
make provision by means of a central rib on the outside of the front wall for
securing a level surface on the bottom of the trap, of the full width of the wall
in which the trap is built.
The
Where the outlet of the trap requires to be vertical, I make the body of the
trap wider at the lower than at the upper part; thus for example the lower
part may he conveniently made 12 inches wide, and rest on a 14 inch wall; and
the upper part 10 inches wide, the wall above it being 10 inches thick.
front wall of the trap is vertical from top to bottom, but the back wall is vertical
at the top and at the bottom; these portions being connected by an inclined
or sloping portion. The spigot outlet is formed in the centre of the bottom,
and communicates, by an inclined passage formed by an inclined cross rib rising
from the bottom towards the front wall, with a front clearing chamber. This
inclined rib is continued sufficiently high, so that its top forms the lip of the
water seal. The space between this inclined rib and the lower vertical part of
the back wall forms the well of the trap. An inclined midriff, with its lower
portion dipping into the well, divides the middle part (considered vertically) of
the trap portion into a rear receiving chamber, with small exposed water sur-
face, and a front inspection and cleaning chamber, which latter is closed at the
top in the manner already above described. Also, as in the trap first described,
a ventilating opening and dropped or hinged ventilating grate or grid are pro-

page_text: vided in the upper part of the front wall above the inspection and cleaning
chamber.
My invention in the second place refers to an improved form of wall box venti-
lator for drains, similar to the upper box portion of the drain traps above de-
scribed; so as to enable such ventilators to be fixed in outside walls close to
public footpaths to give ventilation and access to drains. The box is made with
a circular perforation through its bottom, to admit of the end of a drain pipe, or
pipe connecting to the drain; said end standing a short distance above the
bottom of the box, and around which liquid cement is poured to form, when set,
an airtight joint.
If the drain pipe or the connecting. pipe is not in line of the
wall, but to the outside of the wall, a lateral rectangular opening
is formed in the lower part of the front or outside wall of the
box. In front of this opening, and beneath and with its upper edge
flush with the top of the pavement or road level is placed an access frame, fitted
with a sliding cover plate; said plate having inclined or dovetail edges sliding
in similarly shaped grooves at the top of the sides of the frame; so that whilst
it can be slid back into the interior of the wall box to give access for rodding,
it cannot be mischievously removed; and by means of a plug or bolt, provision
is made to prevent it being similarly left open. Lugs on the frame and box and
bolts are provided for bolting the access frame to the ventilating box.
An open-
ing is provided in the bottom of the access frame or box for the upper end of the
drain pipe or pipe connecting to the drain. The ventilating box may be formed
either with a bottom or a lateral opening, or both; in which latter case, the
opening not used, is hemetically closed. The ventilating grid may be fixed and
secured in either of the ways referred to in the above description of the wall
traps.
And in order that my invention and the manner in which the same is to be
performed may be more readily and clearly understood I have annexed hereto
the accompanying sheets of drawings in which,
Fig. 1 is a vertical section on line A B of Fig. 2, and Fig. 2 is a plan of a com-
bined wall trap and ventilator in which the outlet is arranged laterally.
Fig. 3 is a vertical section on line CD of Fig. 4 and Fig. 4 a part elevation
and part section on line E F of Fig. 3 and Fig. 5 a plan of a combined wall trap
and ventilator in which the outlet is arranged vertically.
Fig. 6 is a vertical section and Fig. 7 a section on line G H of Fig. 6 of a
wall box ventilator to ventilate drains or drain manholes within buildings.
Fig. 8 is a vertical section and Fig. 9 a horizontal section and plan on line IK
of Fig. 8 of a wall box ventilator to ventilate drains or drain manholes or traps
inside or outside buildings and to give access to traps outside buildings.
Fig. 10 is an elevation on line L M of Fig. 8, the access frame being removed
on the right hand side of the figure.
All the above are shewn as constructed in accordance with my invention.
In Fig. 1 and 2 a indicates the body of the trap and b b the front or outside
of the wall in which the trap is built. c is the lateral spigot bend or outlet, over
which fits the socket end of the first drain pipe d.
o is the 'midriff having a double incline, and f the access opening closed by the
two cover plates g and h, between which a clay seal is inserted.
is the lip of the trap, formed by the junction of the lower inclined part of the
front wall and the lower side of the spigot outlet. The lower part of the front
wall' of the trap inclines backward, so as to contract the horizontal section of
the bottom of the body of the trap, whereby the space between the bottom of
the midriff and the back wall is correspondingly reduced, giving a small exposed
water surface for evaporation and emanation.
kis the pavement flag, the level of which is just below the bottom of the
ventilating opening in the front wall of the trap. 7 is a grid iron ventilator,
shewn hinged at its upper end about a bolt m, having its ends let into the sides

page_text: of the body of the trap; so that it can swing inwards as indicated by the curve
dotted line n, and allow access to the body of the trap. The grid iron may
however be dropped in vertical grooves as described later, and shewn in Figs. 3
and 4.
o is a wire screen or strainer supported on corner lugs p. 9 Fig. 2 indicates
the opening in the top of the trap for an internal waste pipe, and r the opening
for the bends, which gives connection for an external fall or waste pipe t.
These openings are formed in one or other of the rear angles of the top of the
body of the trap, which may be provided with either or both these openings
as desired. A recess or ledge is provided in the opening to carry the bottom
of the bends, and the opening r may be made of different diameters, or the upper
end of the bends may be formed of a different diameter to the diameter at the
bottom to accommodate different sizes of fall pipes as indicated by dotted lines
in Fig. 1.
u is a central rib projecting from the inclined bottom part of the front wall
to ensure a proper bearing for the body of the trap.
The same reference letters are used in connection with Figs. 3 to 5 as in Figs. 1
and 2 to indicate the same or corresponding parts, so that it is only necessary
to make special reference to the following.
The lower part of the body of the trap is, as shewn, made wider than the top;
and the lip is formed not by the front wall, but by an inclined cross rib i. The
inclined passage leading to the spigot outlet is contracted towards its lower end
in the section shewn in Fig. 4.
The ventilating grid may be hinged as shewn in Fig. 1, or slide in grooves
formed in the inner sides of the projecting rolls or beads v, see Figs. 3 and 5,
formed round the sides and bottom of the outer side of the ventilating opening.
and secured in the manner already described.
In Figs. 6 to 10 illustrating my improved wall box ventilators, the same
reference letters are used to indicate the same or corresponding parts. Figs. (
and illustrate a wall box ventilator with the outlet or opening to the drain or
manhole arranged laterally in the lower part of the back of the box; whilst in
Figs. 8 to 10 the wall box is shewn with a vertical outlet in the bottom, leading
to a manhole under the basement floor, or to a drain or manhole situated outside
the building, and with an access frame let into the ground flush with the top of
the pavement, and just outside the outer side of the wall of the building.
a indicates the body of the ventilator box and c the outlet opening, which in
the case of the lateral outlet, Figs. 6 and 7, is formed socket wise; and in the
case of the vertical outlet Figs. 8 to 10 is formed with a circular ledge to receive
a jointing of liquid cement. The back wall a¹ is inclined over the upper part.
The ventilator grid may be hinged as illustrated in Fig. 1, or dropped into
vertical grooves formed in the inner sides of the projecting rolls or beads v, and
secured as described, or by a wood plug z, driven into a hole formed for it in the
upper part of the grid; the inner end of the plug x catching beneath the inside
or underside of the top of the wall box.
y Figs. 8 to 10 indicates the access frame, provided with a cover z, having
dovetail edges fitting in dovetail slides 1, formed in the sides of the frame close
to the top. Either or both the back and bottom of the frame may be formed
with an opening; the former opening abutting against a corresponding rect-
angular opening 2 formed in the front wall of the ventilator box below the venti-
lating opening; and the latter opening communicating with the top of the pipe 3
for ventilating and giving access to a drain, trap or manhole beneath the pave-
ment.
The cover z can be slid back into the ventilator box, as indicated by the dotted
lines z¹, to give access; whilst at other times it is secured by a wood plug 4,
driven through holes formed in both of the corner angles of the cover, and
through a rib cast across one or both corner angles of the frame. The top of the
frame and of the cover z are flush with the top of the pavement k.
Y

page_text: Lugs 5 and 6 are formed on the inner sides of the opening at the back of the
frame and on the inner sides of the corresponding opening in the front wall of
the ventilator box; and provided with slots to receive bolts 7, for securing the
iron access frame to the ventilator box.
8 in Fig. 6 indicates a manhole cover, let airtight into the floor of the building
and covering the drain 9.
10 in Fig. 8 indicates a ventilator pipe, passing to a drain or manhole under
the basement floor, or outside the building.
If desired the wall box ventilator illustrated in Figs. 6 and 7 may be provided
with an outside access frame as described in connection with reference to Figs. 8
and 10.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. The construction of wall box trap for drains characterized by the narrowing
of the trap at the bottom by inclining the lower part of the front wall, a pro-
jecting lateral spigot outlet near the lower part in the front wall, a ventilator
opening in the upper part of the front wall provided with ventilator grid, an
inclined midriff and a waste pipe opening or openings in one or both rear angles
in the top of the trap, substantially as and for the purpose or purposes set forth
and substantially as illustrated in Figs. 1 and 2 of the accompanying drawings.
2. The construction of wall box trap for drains characterized by an enlargement
of the trap at the bottom, a depending vertical spigot outlet in the centre of the
bottom, a cross rib inclining upwards towards the front in the lower part of the
body of the trap, a ventilator opening in the upper part of the front wall provided
with ventilator grid, an inclined midriff and a waste pipe opening or openings
in one or both rear angles in the top of the trap, substantially as and for the
purpose or purposes set forth and substantially as illustrated in Figs. 3, 4 and 5
of the accompanying drawings.
3. Outer wall box ventilators for drains characterized by an enlargement of
the box at its lower part towards the back, a socket outlet or opening in the
lower vertical part of the back wall and a ventilator opening in the upper part
of the front wall provided with a grid substantially as and for the purpose or
purposes set forth and substantially as illustrated in Figs. 6 and 7 of the accom-
panying drawings.
4. Outer wall box ventilators for drains characterized by an enlargement of
the box at its lower part towards the back, a circular outlet opening in the bottom,
a ventilating opening in the lower part, and ventilating opening in the upper
part of the front wall provided with a grid, substantially as and for the purpose
or purposes set forth and substantially as illustrated in Figs. 8 to 10.
5. In connection with outside wall box ventilators, the subject matter of
Claims 3 and 4, the combination therewith of an access frame and cover substan-
tially as and for the purpose or purposes set forth and substantially as illustrated
in Figs. 8 to 10 of the accompanying drawings.
6. Wall box traps and ventilators for drains having a rectangular ventilating
opening in the upper part of the outer wall of the trap or ventilator box, round the
sides and bottom of which opening a projecting roll or bead is formed, the side
rolls or beads having vertical grooves on their inner sides, and a ventilating grid
arranged to be dropped into or slid down the said vertical grooves, substantially
as set forth.
J. CLARK JEFFERSON,
30, Park Row, Leeds, Agent for Applicant.