IMPROVEMENTS IN THE MEANS OF AND APPARATUS FOR SANITARILY VEN- TILATING HOUSES, BUILDINGS, ROOMS, CHIMNEY FLUES, SHIPS OR VESSELS, D
Year: 1874

page_text: LETTERS PATENT to Thomas John Hogg, of 42, Fleming Road,
Kennington Park, in the County of Surrey, for the Invention of
"IMPROVEMENTS IN THE MEANS OF AND APPARATUS FOR SANITARILY VEN-
TILATING HOUSES, BUILDINGS, ROOMS, CHIMNEY FLUES, SHIPS OR VESSELS,
D
PROVISIONAL SPECIFICATION left by the said Thomas John Hogg
at the Office of the Commissioners of Patents, with his Petition,
on the 30th December 1874.
I, THOMAS JOHN HOGG, of 42, Fleming Road, Kennington Park, in the
County of Surrey, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE MEANS OF AND APPARATUS for SANITARILY VENTILATING
'HOUSES, BUILDINGS, ROOMS, CHIMNEY FLUES, SHIPS OR VESSELS, SEWers, External
GAS LAMPS, AND OTHER SUCH LIKE PURPOSES," to be as follows:—
My Invention relates to certain improvements in sanitary ventilation,
whereby I am enabled to effect and ensure the collection of impure or
foul atmospheric air, heated air, vapours, fumes, and exhalations in

page_text: .
buildings, rooms, and other situations, and to remove, to effectually carry
off, and to absolutely discharge such impurities into the outer air or space
by stages and degrees. This system of ventilation presents all the
clements of a sanitary process, because it is specially intended to separato
and control vitiated air and oxhalations by self-acting apparatus whereby,
and by the consequent influx of pure air, a vortex, suction, and exhaus-
tion of air and exhalations and other impurities are caused, and consc-
quently an effectual though imperceptible circulation of air and´a
continuous influx of the same is produced, from any possible point or
place of ingress, the same circulating and flowing to the position of the
apparatus. Thus it will be clear that my apparatus serves primarily and
specially to exhaust impurities of air, it has no duty to perform as to the
supply of fresh air, which of necessity must naturally take place, as
my suctional and exhausting apparatus withdraws vitiated air, and
it is only when ventilating chimnics that I control the supply of
fresh air.
I propose in regard to rooms or buildings, according to their size, to
make one or several apertures in the ceiling, roof, or walls (except when
ventilating outer gas lamps), such apertures forming communications,
whereby the impure air is to pass into the apparatus, and through all
parts thereof, such apertures being obscured by the application of some
ornamental work.
In connexion with the apertures I fix a suctional metal chamber,
within which I construct or more metal shelves of equal area with
the chamber, each a few inches apart, and each perforated with any
number of air holes, the lowest shelf or division having the smallest
holes, and the uppermost one the largest.
Above the highest division in the space remaining in the chamber,
and near an outlet formed therein, I apply a rotary fan with wings or
fans composed of silk, talc, or gossamer material, or of thin metal or other
suitably light substance; and to prevent noise during its rotation I set
its shaft or axle in bearings of india-rubber, cork, vulcanite, or similar
material. This fan wheel rotates by the action of the air and exhala-
tions drawn into the chamber (which from its arrangements and effects
constitutes a suctional container) and the rotation supplies impetus to
the ventilated air and oxhalations and other impurities drawn in whereby
they are caused to travel and pass onward from without, into and

page_text: Through an air-tight conduit pipe, and thence onward or upward into a
metal reservoir of large size comparatively to the chamber. These
air-tight conduits or pipes may be of zinc or other metal, but it is
essential that they should be provided with a small internal tube of finely
perforated metal, the effect of which will be that the motion of the
current of air and impurities will be excited and stimulated, and that
suction and exhaustion will be created at the inlet to the suctional
chamber, and when several chambers are employed separato conduit
pipes must connect them with the reservoir.
In the reservoir I fix a similar fan wheel to that described for the
chamber, such wheel rotating in the direction of an outlet provided as
before, and I also apply to cach inlet of the reservoir a non-return or
clack valve opening one way only to suit the ingress of impure air
withdrawn ; and finally, I convey the contents of the reservoir by suitable
air-tight conduit pipes to a metal chamber and condenser. This final
chamber or condenser should be about one-half the dimensions of the
reservoir. Internally it is fitted with a rotary fan, as last described, and
also with a non-return-valve, and I fix in the lowest part of the con- .
denser an air box of metal or wood containing three or more shelves
or coverings of fincly perforated sheet metal, through which is caused
to percolate a minimum draught of cold air supplied thereto by means
of any ordinary tube or pipe connected therewith, its opposite end being
connected with an ordinary bell trap to be inserted in an outer wall (at
as near a point as possible opposite to that of the outflow from the
conduit pipes), into which the outer air and draught can enter freely.
A valve is applied to the pipe and within the condenser, covering the inlet
to the air box to prevent the egress of air from the condenser to the pipe.
The object of this part of my Invention is to afford extra power to
the onward current or flow towards the point of exit and to counteract
the force of external currents which would otherwise oppose the
discharge of the impure air into the outer air.
From the condenser the impure air is forced out partly by the pressure
created by the greater chamber emptying itself into the smaller one and
partly by the auxiliary force supplied by the air box and its appliances.
The course is continued by conduit pipes to the convenient place of exit
or discharge, which may be directly into the open air or into a chimney
flue, or into the chimney or ventilator of an outside gas lamp.

page_text: 6
The air tube or discharge pipe should be of metal not less than two
inclics in diameter and of any convenient length, the longer the better.
The tube is closed at the bottom, and its inlet connected with the conduit
tubes should essentially be about midway of its length and not at either
extremity. Its position should be vertical, or as nearly so as possible.
This construction effects an expulsion or discharge of the air and
exhalations passed or conveyed into the tube, notwithstanding tho
opposition of the outer or surrounding air. The upper portion of the
tube should be reduced to about half the diameter of the lower portion,
and when used in the open air I surmount it by a moveable wind guard 1
and spreader having wings or fans of metal fringed with perforated
metal gauze or wire, so as to fully surround the entire outer opening
and prevent anything from entering the tube. And when the tube is
fixed in a chimney fluc a stationary cowl as a protection from soot or
rain.
In ventilating into outside gas lamp chimneys or ventilators, more
especially in connection with shop ventilation, I dispense with the use of
-the air tube last described and substitute an improved and better adapted
gas lamp ventilator formed of a metal rim or plate either flat, corrugated,
or turned up or down, and set well over the crown or upper part of the
lamp, its lower surface facing the interior thereof. It should be highly
reflective by being lined or coated with silvered glass or other well known
suitable material, and resting upon and around the said rim I place a
ring tubes, into which, by means of tubes, I convey the impure air from
the conduit tubes, and these pass thence into a square perforated metal
box fitted thereon, and then into a continuation of the ventilator made
in a pyramidal or other form, whence the impure air escapes into the
outer atmosphere. The ventilator is to be surmounted by a fixed wind
guard and protector to guard against rain and down draught.
In the application of my apparatus to sewage ventilation I employ
chiefly galvanized iron, and employ tubes to carry off any distillation of
vapours, such tubes being applied and fixed to any ordinary public street
lamp, the ventilation communicating therewith from my conduit pipes
through the lamp column, and thence by other pipes or tubes into my
aforesaid lamp ventilator, or by pipes outside the lamp column and
attached thereto, or in some cases by pipes along a standard specially
provided with a gas light and gas lamp ventilator as before.

page_text: in ventuating ships 1 apply the same apparatus as used for house
ventilation, except as to the gas lamp ventilator.
In regard to chimney flue ventilation, or the avoidance of the
down draught which causes what are commonly described " smoky
chimnies," I dispense with the air box and its accessories, with the air
tube and the gas lamp ventilator, and I construct the parts of galvanized
iron (by preference) but partly of zinc or other metals. I fit the
suctional chamber in communication with the outer air direct, and into
the outer wall below the level of the room. The remaining appliances I
place beneath the floor enclosed by brickwork or not; I then attach any
ordinary metal pipe to the end of my conduit pipe, and continue the
same beneath the hearth or as near thereto as possible till a point is
reached immediately beneath the fire-grate. I insert into the brickwork
at each side and at the back beneath the fire a small iron bell trap, and
effect communication therewith by attaching the outlet of the pipe
thereto, and thereby cause a precolation of air and draught, thus effecting
a rapid upward current in the chimney fluc, counteracting the downward
current and enabling the smoke to escape with perfect case, thereby
diminishing the accumulation of soot and enabling a fire to be main-
tained at a red heat even when only slag mixed with coal dust is used.
By a minimum flow of air a fire of small coal or dust and cinders may
be maintained for a great length of time, especially as in smithy fires.
The extent of draught is easily regulated by an ordinary valve or stop-
cock.
I have given the foregoing examples of the application of my improved
system of sanitary ventilation because they represent the most prominent
uses to which it would commonly be applied, but it is evident that other
situations might be enumerated in which the Invention wholly or in part
would be equally applicable, as for instance to the ventilation of coal
mines, but in any case it must be perfectly evident that the Invention is
based purely on the known and admitted laws of pneumatics, and is
rendered automatic in its continuous, incessant action, thus ensuring the
existence of wholesome air in any dwelling or situation mentioned (and
in hospital wards, especially those for infectious diseases, such a condition
of things is all important). The operation of ventilation is consequently
free from all sudden change; it is gradual and enduring, always
increasing or decreasing, exactly in the required ratio, according to tho

page_text: temperature of the air or the artificial heat of the room or place to be
purified.
The apparatus is inexpensive and simple, and when once adjusted is
exceedingly durable, requiring no care or supervision, and yet capable of
being regulated to the greatest exactitude, and such are the chief 5
advantages subservient to the main objects of collecting and continuously
discharging the vitiated air and exhalations as described, all of which
constitute the subject matter of this Invention.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas John Hogg in the Great Seal Patent ||
Office on the 30th June 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Tuomas
JOHN HOGG, of 42, Fleming Road, Kennington Park, in the County of
Surrey, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 1
Letters Patent, bearing date the Thirtieth day of December, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-eighth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Thomas John Hogg, Her
special licence that I, the said Thomas John Hogg, my executors, a
administrators, and assigns, or such others as I, the said Thomas
John Hogg, 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 In-
vention for "IMPROVEMENTS IN THE MEANS OF AND APPARATUS FOR SANITARILY
VENTILATING HOUSES, BUILDINGS, ROOMS, CHIMNEY FLUES, SHIPS OR VESSELS,
SEWERS, EXTERNAL GAS LAMPS, AND SUCH LIKE PURPOSES," upo ntho condition
(amongst others) that I, the said Thomas John Hogg, my executors or
administrators, by an instrument in writing under my, or their, or onc
of their hands and scals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to
bo performed, and cause the same to be filed in the Great Seal Patent

page_text: Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas John Hogg, 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:-
My Invention relates to certain improvements in sanitary ventilation,
whereby I am enabled to effect and ensure the collection of impure or
foul atmospheric air, heated air, vapours, fumes, and exhalations in
buildings, rooms, and other situations, and to remove, to effectually carry
off, and to absolutely discharge such impurities into the outer air or space
by stages and degrees. This system of ventilation presents all the
clements of a sanitary process because it is specially intended to separate
and control vitiated air and exhalations by self-acting apparatus, whereby
and by the consequent influx of pure air, a vortex suction and exhaustion
of air and exhalations and other impurities are caused, and consequently
an effectual though imperceptable circulation of air, and a continuous
influx of the same is produced from any possible point or place of ingress,
the same circulating and flowing to the position of the apparatus. Thus
it will be clear that my apparatus serves primarily and specially to
exhaust impurities of air, it has no duty to perform as to the supply of
fresh air, which of necessity must naturally take place, as my snctional
and exhausting apparatus withdraws vitiated air, and it is only when
ventilating chimnics that I control the supply of fresh air. (Since the
date of my Provisional Specification, I have discovered in practice that
the parts described by the words shewn in-italics (or underlined) is not
necessary and is useless, and I therefore abandon the use thereof).
I propose in regard to rooms or buildings according to their size, to
make one or several apertures in the ceiling, roof, or walls (except when
ventilating outer gas lamps), such apertures forming communications,
whereby the impure air is to pass into the apparatus and through all
parts thereof, such apertures being obscured by the application of some
ornamental work.
In connection with the apertures I fix a suctional metal chamber,
within which I construct three or more metal shelves of equal area with
the chamber, each a few inches apart, and cach perforated with any

page_text: number of holes, the lowest shelf or division having the smallest holes,
and the uppermost one the largest.
Above the highest division in the space remaining in the chamber and
near an outlet formed therein, I apply a rotary fan with wings or fans
composed of silk, talc, or gossamer material, or of thin metal or other {
suitably light substance, and to prevent noise during its rotation I set its
shaft or axle in bearings of india-rubber, cork, vulcanite, or similar
material. This fan wheel rotates by the action of the air and exhalations
drawn into the chamber (which from its arrangements and effects
constitutes a suctional container), and the rotation supplics impetus to
the ventilated air and exhalations and other impurities drawn in, whereby
they are caused to travel and pass onward from without into and through
an air-tight conduit pipe, and thence onward or upward into a metal
reservoir of large size comparatively to the chamber. These air-tight
conduits or pipes may be of zinc or other metal, but it is essential that
they should be provided with a small internal tube of finely perforated
metal, the effect of which will be that the motion of the current of
air and impurities will be excited and stimulated, and that the suction
and exhaustion will be created at the inlet to the suctional chamber, and
when several chambers are employed separate conduit pipes must connect
them with the reservoir.
In the reservoir I fix a similar fan wheel to that described for the
chamber, such wheel rotating in the direction of an outlet provided as
before, and I also apply to cach inlet of the reservoir a non-return or
clack valve, opening one way only to suit the ingress of impure air with-
drawn, and finally I convey the contents of the reservoir by suitablo air-
tight conduit pipes to a metal chamber and condenser. This final
chamber or condenser should be about one half the dimensions of tho
reservoir; internally it is fitted with a rotary fan as last described, and
also with a non-return valve, and I fix in the lowest part of the condenser
an air box of metal or wood containing three or more shelves or coverings
of finoly perforated sheet metal, through which is caused to percolato a
minimun draught of cold air supplied thereto by means of any ordinary
tube or pipe connected therewith, its opposite end being connected with
an ordinary bell trap to be inserted in an outer wall (at as near a point
as possible opposite to that of the outflow from the conduit pipes), into
which the outer air and draught can enter freely. A valve is applied to

page_text: the pipe, and within the condenser, covering the inlet to the air box to
prevent the egress of air from the condenser to the pipe.
The object of this part of my Invention is to afford extra power to
the onward current or flow towards the point of exit, and to counteract
the force of the external currents which would otherwise oppose the
discharge of impure air into the outer air.
From the condenser the impure air is forced out partly by the pressuro
created by the greater chamber emptying itself into the smaller one, and
partly by the auxiliary force supplied by the air box and its appliances
the course is continued by conduit pipes to the convenient place of exit
or discharge, which may be directly into the open air, or into a chimney
flue, or into the chimney or ventilator of an outside gas lamp.
The air tube or discharge pipe should be of metal, not less than two
inches in diameter, and of any convenient length, the longer the better.
The tube is closed at the bottom, and its inlet connected with the
conduit tubes should essentially be about midway of its length, and not
at either extremity. Its position should be vertical, or as nearly so as
possible. This construction effects an expulsion or discharge of the air
and exhalation passed or conveyed into the tube, notwithstanding the
opposition of the outer or surrounding air. The upper portion of tho
tube should be reduced to about half the diameter of the lower portion,
and when used in the open air I surmount it by a moveable wind guard
and spreader, having wings or fans of metal fringed with perforated
metal gauze or wire so as to fully surround the entire outer opening and
prevent anything from entering the tube; and when the tube is fixed
in a chimney flue a stationary cowl as a protection from soot or rain.
In ventilating into outside gas lamp chimneys or ventilators, more
especially in connection with shop ventilation, I dispense with the use of
the air tube last described and substitute an improved and better adapted
gas lamp ventilator formed of a metal rim or plate, either flat, corrugated,
or turned up or down, and set well over the crown or upper part of tho
lamp, its lower surface facing the interior thereof. It should be highly
reflective by being lined or coated with silvered glass or other well-
known suitable material, and resting upon and around the said rim I
place a ring tube, into which by means of tubes I convey the impure air
from the conduit tubes, and these pass thence into a square perforated
metal box fitted thereon, and then into a continuation of the ventilator
-

page_text: made in a pyramidal or other form, whence the impure air escapes into
the outer atmosphere. The ventilator is to be surmounted by a fixed
wind guard and protector to guard against rain and down draught..
In the application of my apparatus to sewage ventilation I employ
chicfly galvanized iron, and employ tubes to carry off any distillation
of vapours, such tubes being applied and fixed to any ordinary public
street lamp, the ventilation communicating therewith from my conduit
pipes through the lamp column, and thence by other pipes or tubes into
my aforesaid lamp ventilator, or by pipes outside the lamp column, and
attached thereto or in some cases by pipes along a standard specially
provided with a gas light and gas lamp ventilator as before.
In ventilating ships I apply the same apparatus as used for houso
ventilation, except as to the gas lamp ventilator.
In regard to chimney flue ventilation or the avoidance of the down
draught, which causes what are commonly described "smokey chimnies,"
I dispenso with the air box and its accessories with the air tube and the
gas lamp ventilator, and I construct the parts of galvanized iron (by
preference), but partly of zinc or other metals. I fit the suctional
chamber in communication with the outer air direct and into the outer
wall below the level of the room. The remaining appliances I place :
beneath the floor enclosed by brickwork or not; I then attach any
ordinary metal pipe to the end of my conduit pipe and continue tho
same beneath the hearth, or as near thereto as possible till a point is
reached immediately beneath the fire-grate. I insert into the brickwork
at each side and at the back beneath the fire a small iron bell trap, and
effect communication therewith by attaching the outlet of the pipe
thereto, and thereby cause a percolation of air and draught, thus effecting
a rapid upward current-in the chimney flue counteracting the downward
current, and enabling the smoke to escape with perfect case, thereby
diminishing the accumulation of soot and enabling a fire to be a
maintained at a red licat even when only slag mixed with coal dust is
used.

page_text: I have given the foregoing examples of the application of my improved
system of sanitary ventilation because they represent the most prominent
uses to which it would commonly be applied, but it is evident that other
situations might be enumerated in which the Invention wholly or in
part would be equally applicable, as for instance to the ventilation of
coal mines, but in any case it must be perfectly evident that the Inven-
tion is based purely on the known and admitted laws of pneumatics, and
is rendered automatic in its continuous incessant action, thus ensuring
the existence of wholesome air in any dwelling or situation mentioned
(and in hospital wards, especially those for infectious diseases such a
condition of things is all important). The operation of ventilation is
consequently free from all sudden change, it is gradual and enduring
always increasing or decreasing exactly in the required ratio, according
to the temperature of the air or the artificial heat of the room or place
to be purified.
The apparatus is inexpensive and simple, and when once adjusted is
exceedingly durable, requiring no care or supervision, and yet capable
of being regulated to the greatest exactitude, and such are the chicf
advantages subservient to the main objects of collecting and continuously
› discharging the vitiated air and exhalations, as described, all of which
constitute the subject matter of this Invention.
But that my improvements may be better understood I will now
proceed by the aid of the accompanying Drawings more fully to describe
the same with examples of the best means I am acquainted with for
5 carrying the same into practical effect.
Figs. A, B, and C represent an external and longitudinal view of the
several vessels comprised in my improvements, and severally named as
follows: A is the receiver; B, the reservoir; C, the condenser; all of
which are connected by means of the conduits pipe marked 2 in the
) several Figures, having also connected therewith by the same means
Fig. D, which shows an external and vertical view of the air pipe when
used out in the open air.
Figures A a, Bb, Cc, and Dd, shew a sectional view of the same
Figures similarly placed but exposing their interior parts to view; these
5 Figures as above described shew an example of one arrangement of the
said vessels, tubes, and other appliances when fitted up for the purpose

page_text: of efflux ventilation, being the ono I prefer when and where the same
can be adopted.
Figs. A, A, B, B, and D, D, represent the appliances applied to
influx purposes. Fig. A, A, shews the receiver in the position of
laying upon its side and exhibiting the fincly perforated metal plate
marked 3 in the Figures respectively, and through the perforations of
which the external or fresh air will pass into the interior of the said
receiver, whence it will pass through the conduit tube 2 into the
reservoir B, B, and thence into the air tube D, D, from which it will be
vertically expelled into the apartment or place wherein it be fixed or :
fitted through a plain or ornamental pipe, Fig. D', such air being
regulated in its force and quantity by means of a thumb piece connected
by means of a spindle to a disc of metal fitted into the said pipe D', as
shewn at the dotted lines therein, the external perforated plate of Fig.
A, A, is to be flush with the outer wall or otherwise of the building or 1
place requiring to be supplied with such external or fresh air; this
arrangement or a modification thereof to suit the circumstances of the
place where the same is to be applied is the one I prefer when adapting
the influx part of my improvements.
The numerals in each of the Figures shown in the Drawings apply to
the same parts respectively in cach Figure, the arrows in the same
manner the direction the air takes in its passage from the receiver to the
air tubo both in efflux and influx ventilation.
The Figures shewn in section will readily render generally the interior
arrangement of parts comprehensive. 3, 3, 3, show the position of the 2
perforated metal plates; 4, 4, shews the interior of cach Figure A a, B b,
and Cc, to be somewhat cliptical, so made by having one or other of such
pieces of metal, as shewn at Figs. F and G, fixed in the corners thereof
respectively, thereby giving greater facility for the air to pass in tho
direction of the arrows; 5, 5, shows a valve or fan, as shown at Fig. N, 3
or other kind capable of being made to revolve on an axis; 6, 6, shows
the perforated tube; 7, 7, shows a moveable lid, by the removal of
which the interior of each vessel can be examined if necessary; 8, 8,
shews a hole in the bottom of a metal box, shown on an enlarged scale
at Fig. E, having a flap or clack valve 8', its edges being turned back so 3
that it may be fixed in its proper place, as seen in Figs. B b, and C c ;
9, 9, shows at the dotted line the space and direction tho said valvo

page_text: moves in when back or down draught is pressing against its under side
through the hole 8, though it is quite improbable that any return air or
down draught can take place, and as a further preventative against it I
uso a valve, as shewn at Figs. L and M, the spindle of which I pass
and
through the air box at 10, Fig. C c. This valvo is acted upon
depressed by the compressed air in the condenser, which when it is. too
feeble to so act on the valve, the external air being the strongest, rushes
up the tube at 10, and so aids or assists the entire contents in their
expulsion from the condenser, thence into the air tube, and finally into
the open air or space, which process creates a kind of vacuum, thereby
causing circulation of air in the direction of the point of exit, and as
shewn by the direction of the arrows 3¹, 3¹, shows air holes at the baso
of the air tube through which air passes to assist the expulsion of the air
from Fig. 2 therein out at the top through the perforations 5 and 3ª
surmounted by 4', a cover to exclude rain, &c.; 4°, 4°, shews a pyramidal
contrivance to increase the strength of the currents of air at the point of
exit of Fig. D d; Fig. K shews the adaptation of my perforated and
pyramidal ventilator to outside lamps; 2, 2, the conduit pipe; 6', per-
forated rim to 71; 8, the top of the lamp.
As to the exact dimensions or shape of any or all of the said vessels
and appliances, whether for efflux or influx ventilation, the relative
position of cach to the other and the part at which the conduit pipes
shall enter or leave the said vessels or any one of them, together with
the arrangement of the appliances and their interior or exterior parts,
must manifestly be determined upon, according to the circumstances and
place in or to which the same is to be applied, such as whether fitted
between joists in the ceiling, on roofs, along or in walls, beneath the
floorings or upon floorings, to window sashes, or in any other position
or respect. The larger the said vessels and their several appliances are
) or the greater the aggregate of their several dimensions the moro
powerful will be the results obtained from their operation.
Having thus described the nature of my said Invention, and the best
means I am acquainted with for carrying the same into effect, I would
have it understood that I do not confine myself to the precise usc and
5 arrangement of the parts shewn and described, so long as the main
features of my said Inventions are adhered to, but what I claim and
desire to be secured by the herein-before recited Letters Patent is, the
improvements in efflux and influx ventilation, substantially by the means

page_text: and in the manner herein described and shown in the Drawings hereto
annexed, or any mere modification thereof.
In witness whereof, I, the said Thomas John Hogg, have hereunto
set my hand and scal, this Thirtieth day of June, in the year of
our Lord One thousand eight hundred and seventy-five.
Witness,
WILLIAM MILLS,'
New Wimbledon,
S.W.
THOMAS JOHN HOGG. (L.S.)