AN IMPROVED VEN- TILATOR
Year: 1866

page_text: COMPLETE SPECIFICATION filed by John Thomas Kershaw at the Office.
of the Commissioners of Patents, with his Petition and Declaration,
on the 9th November 1866, pursuant to the. 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
THOMAS KERSHAW, of No. 90, Saint Paul's Road, in the Parish of Islington,
in the County of Middlesex, Surveyor, send greeting.
WHEREAS I am in possession of an Invention for "AN IMPROVED VEN-
TILATOR," and have petitioned Her Majesty to grant unto me, my executors,
administrators, and assigns, Her Royal Letters Patent for the same, and have
made solemn. Declaration that I am the true and first Inventor thereof..
NOW KNOW YE that I, the said John Thomas Kershaw, do hereby
declare that the following Complete Specification, under my hand and seal,.
fully describes, and ascertains the nature of the said Invention, and in what
manner the same is to be performed, in and by the following statement (that
is to say).
I fix into the chimney of the room, or apartment, or shop which is to
be ventilated, if such said room, or apartment, or shop has a chimney con-
nected with a fire-place therein, or if such said room, or apartment, or shop
has no such chimney and fire-place therein, then into such chimney, if any,

page_text: .
passing up the side or end of such room, or apartment, or shop as may be con-
nected with a fire-placè in some room or apartment or shop below or adjoining
to the said room, or apartment, or shop which is to be ventilated, and in
which last-mentioned fire-place a fire is usually kept burning, a metal frame
of the following proportions, that is to say, of a height from out to out varying
from four-sevenths of the depth of the flue to somewhat less than the depth of
the flue and of a width from out to out somewhat less than the width of the
flue in which the said frame is fixed. The depth of the said frame is to-be
of the depth of the chimney breast of the chimney into which the said frame
is fixed; the thickness of the sides of the said frame need not be more than
quarter of an inch. To the said frame I fix a back or valve (of which the
height and width is the same as the height and width of the said frame) hinged
either to the lower part of the said frame or else hinged to a plate securely
fixed in the bottom of the said. frame .in such manner that the said back or
valve will fall inwards into the chimney. To the aforesaid back or valve I
fix a weight or spring in such manner that, the aforesaid back or valve shall
always have a tendency to fall open... I also fix to the aforesaid back or valve
a cord, which it is desirable should be a wire cord,-which said cord I cause to
pass over a pulley fixed to the top or bottom of the aforesaid frame, by pre
ference to the top thereof, which cord I continue down the front of the
chimney breast; this cord I make of a convenient length; and secure it to any
convenient fastening in such manner that I can either shut the aforesaid back
or valve close against the aforesaid frame, or that I can allow the aforesaid
back or valve to fall freely open, or that I can fix the aforesaid back or valve
in any position intermediate between being fully open or being completely
closed. The above are the essential parts of the apparatus. I also fix in
front of the iron frame a face plate which may be ornamented according to
pleasure, provided always that in ornamenting this said face plate sufficient
open space be left therein for the foul air to pass freely through the frame into
the chimney. And because some chimney breasts have a greater thickness from
the front thereof to the flue than most other chimney breasts have, I make in
such cases a second frame of iron which shall be capable of working with a
telescopic motion within the first aforesaid iron frame. To or upon this inner
frame I then fix the
fix the aforesaid back or valve in such manner that the back or
valve shall when closed coincide with the inside of the chimney breast.
The action of the above described ventilátor is as follows:-The door or valve
when' 'open 'falls into the flue of the chimney, and thereby to a greater or 'less
extent throttles" the said 'flue, and by so doing prevents it withdrawing from
the lower part of the apartment to be ventilated, or from the lower part of the

page_text: apartment below or adjoining, as the case may be, that quantity of air which
it would otherwise do, but yet allows the said flue or chimney to withdraw from
the one or other said apartment so much air as is necessary to carry off the
smoke and the products of combustion of the fuel which may be being con-
sumed. By thus throttling the chimney it is compelled to withdraw that
further quantity of air which it is capable of carrying off from the upper part
of the room, apartment, or shop to be ventilated, and the force with which
this last-mentioned portion of air passes through the said ventilator into the said
chimney is sufficient to prevent all egress of smoke from the chimney through
the ventilator.
I wish it to be particularly understood that I do not confine myself to the
precise details, as herein described, but that what I claim as of my Invention
is, the adoption of a back or valve falling into the chimney in such manner as
to throttle the said chimney and to prevent it withdrawing from the lower part
of the room, apartment, or shop to be ventilated, or from the lower part of
the room, apartment, or shop below or adjoining, all the air it is capable of
carrying off, and so compelling the chimney to withdraw the rest of the air it
is capable of carrying off from the upper part of the room, or apartment, or
shop to be ventilated, which air is the hot or impure air to be got rid of.
In witness whereof, I, the said John Thomas Kershaw, have hereunto
set my hand and seal, this Ninth day of November, in the year of our
Lord One thousand eight hundred and sixty-six.
JOHN THOS. KERSHAW. (L.S.)
Applicant.
This is the Specification referred to in
the annexed Declaration of John
Thomas Kershaw, taken before me
this 9th day of November 1866.
JA. MURRAY.