IMPROVEMENTS IN APPARATUS FOR PREVENTING DOWN DRAUGHT IN CHIMNEYS, AND FOR PROMOTING VENTILATION AND THE WITHDRAWAL OF AIR, OR GASES FROM ROOMS, SEWERS, OR OTHER PLACES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by James Baker at the Office of the
Commissioners of Patents on the 19th October 1883.
JAMES BAKER, of Penge, in the County of Surrey " IMPROVEMENTS IN
APPARATUS FOR PREVENTING DOWN DRAUGHT IN CHIMNEYS, AND FOR PROMOTING
VENTILATION AND THE WITHDRAWAL OF AIR, OR GASES FROM ROOMS, SEWERS, OR
OTHER PLACES,"
This Invention relates to cowls, or apparatus for preventing down draughts in
chimneys, and which can also be used for withdrawing air from shafts for the
purpose of ventilation, or for exhausting air or gases from rooms, sewers, or other
places.
In order to put the invention in operation, I arrange upon the upper end of the
chimney to which the apparatus is to be applied, or of a pipe or tube through
which gas or air is to be withdrawn, a pipe preferably of metal fitting upon or in
the chimney or other pipe and having its upper end slightly expanded. Outside
the upper end of this metal pipe I fit or make a cylindrical chamber of larger
diameter the lower end of which is made preferably conical and descends and is
fixed at a point somewhat below the expanded top of the pipe.
Its upper end is closed by a plate rising in inclined or conical form and having a
central opening of a diameter about equal to that of the inner metal pipe.
To this plate, or to the sides of the chamber is fixed a frame or support carrying
a central vertical pivot upon which a revolving cowl can turn freely.
The revolving cowl consists of a vertical cylindrical chamber the lower edge of
which fits freely round the upper edge of the cylindrical part of the inner chamber
whilst its upper edge at a sufficient height above is closed by a flat borizontal plate
surmounted by an ornamental conical or other cover fitted with sockets which turn
upon the vertical pivot, and provided with a vane of the usual kind by which the
cowl is made to revolve upon the pivot by the action of the wind.
Upon one side of the cylindrical part of the cowl a rectangular opening is made
the width of which is about equal to the diameter of the opening in the cover of
LD071

page_text: the central chamber, whilst its upper edge is level with the flat plate forming the
top of the cowl and its lower edge is level with the junction of the conical top and
the cylindrical part of the inner chamber.
This rectangular opening is made in such a position in relation to the vane that
it is always kept turned from the point from which the wind is blowing, and
exactly opposite to it is a second rectangular opening of the same or somewhat
greater width, its upper edge being slightly below that of the opposite opening, and
its lower edge somewhat above the lower edge of the latter.
Round the upper edge of the second opening described is formed or fixed an
external flange of sufficient width projecting outward and downward, and across the
opening preferably at equal distances apart are fixed two or more similar flanges
projecting outward and downward,
The action of the apparatus is as follows:-The second opening described being
turned toward the wind the latter strikes the projecting and descending flanges
and is deflected by them upward and across the opening in the conical top of the
inner chamber, up which a strong draught is induced, the smoke air, or gas, being
thus drawn up and expelled with the escaping current of wind through the opposite
opening which is always turned from the direction of the wind as described.
The position and shape of the inclined projecting flanges and of the conical top
of the inner chamber prevent the possibility of any current of wind being directed
down the chimney, and the flange at the upper edge of the opening prevents the
wind from entering and striking the flat top of the cowl and being then deflected
down the chimney.
I make the support of the central pivot of such shape that it presents as little
surface as possible to the entering wind.