An Anti-blow-down, Smoke Draught Improving, and Ventilating Apparatus.
Year: 1892

page_text: Date of Application, 15th Feb., 1892
Complete Specification Left, 23rd May, 1892-Accepted, 23rd July, 1892
PROVISIONAL SPECIFICATION.
An Anti-blow-down, Smoke Draught Improving, and
Ventilating Apparatus.
JOHN MORTON DUNCAN, Undercraig, Langbank, Renfrewshire, Scotland,
Schoolmaster do hereby declare the nature of this invention to be as follows:-
The apparatus has been invented for the purpose of preventing a blow-down in
chimneys, and for the purpose of assisting the upward draught in chimneys and
ventilating air funnels. This is accomplished by the revolution of a screw propeller
so fixed on a shaft as to send a current of air up the chimney or air funnel. The
propeller may be placed at a greater or less distance down the said chimney or air
funnel as may be found most effective. For ordinary dwelling house chimneys a
length, such as that shown in the plan sent, reaching down to about the bottom of
the chimney can I find quite effective; but for ventilating air shafts or funnels
which have few, if any, bends the propeller can be fixed to a longer shaft reaching
further down, and, if need be, one or more tandem screw propellers may be fixed
on the shaft. The shaft bearing the propeller is driven by an apparatus fixed at
the top called the driver which is kept in motion by the wind. The driver, shaft
and propeller being the movable parts are supported by a part of the apparatus
called the cage, on a bearer at the lower part of which, the shaft, tapered to reduce
friction, rests. On the top of the cage and about one inch below the lower side of
the driver is a circular metallic plate bolted or otherwise fixed down. This plate
serves three very important purposes;-1st, it catches the wind and throws it by
reflection on to the blades of the driver; 2nd, it prevents the wind from blowing
directly down the chimney or air funnel; and 3rd, it keeps the rain off the opening
of the said chimney or air funnel. The open space under the plate may be
surrounded by perforated zinc or wire gauze if thought necessary.
The following are the parts of the apparatus of which the plans, drawn to a
scale of inch to the inch, or th full size, are sent, showing a form of the apparatus,
and illustrating its main features.
A. Driver. This is composed of two metallic wheels (a), (in plan 12 inches
diameter and 8 inches apart but may be any size according to work to be done).
On these are supported several semi-cylindrical or other shaped blades which catch
the wind and cause the revolution of the apparatus. The driver is rigidly fixed
to the top of the shaft.
B. Shaft. This is made of steel, iron, or other metal and is 36 inches long and
inch thick on plan but may be made any size to suit work required. It rests on
the lower bearer (d). At or near the end of the shaft is fixed the propeller.
C. Propeller. This may be made with 2 or 4 blades as may be required and is
for the purpose of creating, when it revolves, an upward current of air.
D. Cage. This is composed of 2 bearers, an upper (c) and a lower (d) made of
brass or other metal to support the shaft, and 4 bars (e) of iron bent and fixed
into the bearers as shown. The bends at f rest on the chimney can or air funnel.
The lower bearer (d) on which so much depends for the support and smooth action
of the movable part of the apparatus is shown in section actual size. (g) is a
movable screw for adjustment and (4) is a disc of a peculiarly hard metal on which
the point of the shaft revolves. (i. i) are 2 circular metallic bands to bind the
cage firmly together.
D₁ D" are plans of upper and lower ends of cage. The body of the cage may
be done away with if the air funnel is long, and only the upper and lower ends,
fixed into the funnel itself used. E is the circular metallic plate, which in the

page_text: plan is 13 in. in diameter with edges turned down in. but which may be of any
suitable size.
Dated this 13th day of February 1892.
COMPLETE SPECIFICATION.
An Anti-blow-down, Smoke Draught Improving, and
Ventilating Apparatus.
JOHN MORTON DUNCAN, Undercraig, Langbank, Renfrewshire, Scotland,
Schoolmaster, do hereby declare the 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 :-
The apparatus has been invented for the purpose of preventing a blow down in
chimneys and for the purpose of assisting the upward draught in chimneys and
ventilating air funnels. This is accomplished by the revolution of a screw propeller
so fixed on a shaft as to send a current of air up the chimney or air funnel. The
propeller may be fixed at a greater or less distance down the said chimney or air
funnel as may be found most effective. For ordinary dwelling house chimneys a
length such as that shown in the elevation sent (Sheet 1") reaching down to about
the bottom of the chimney-can I find quite effective, but for ventilating air shafts
or funnels which have few, if any bends, the propeller may be fixed to a longer
shaft reaching further down, and, if need be, one or more tandem screw propellers
may be fixed on the shaft. The shaft bearing the propeller is driven by a part of
the apparatus fixed at the top, called the driver, which is kept in motion by the
wind. The driver, shaft, and propeller, being the movable part, are supported by
a part of the apparatus called the cage, on a bearer at the lower part of which the
shaft, tapered to reduce friction, rests. On the top of the cage, and about one inch
below the lower side of the driver is a circular metallic plate, bolted or otherwise
fixed down. This plate serves three very important purposes:-1st, it catches the
wind and throws it by reflection on to the blades of the driver: 2nd, it prevents
the wind and rain from blowing directly down the chimney or air funnel: and
3rd, it prevents the smoke from entering the driver and choking its blades with
soot. For ventilation purposes the open space under the aforesaid plate from
which the air escapes may be surrounded by perforated zinc or wire gauze to keep
out birds, or the upper part of the apparatus, including the driver and the air
outlet may be enclosed by a framework of louvre plates, the plan of which is shown
on Sheet 2 and the elevation on Sheet 3 of the annexed set of drawings. This
framework of louvre plates which is supported on brackets fixed to the cage, and
detachable, is for the purpose of guiding the wind more directly on to the blades
of the driver and so causing it to revolve at a greater velocity. The lower
band () of this framework protects the opening of the air passage from rain.
The following are the parts of the apparatus of which the plans, drawn to a
scale of inch to the inch or one fourth of the full size, are sent, showing a form
of the apparatus and illustrating its main features.
A (Sheet 1). The driver. This is composed of two metallic wheels (a) which,
in plan are 12 inches in diameter, and about 8 inches apart, but which may be any
size according to work to be done. On these are supported or fixed several semi-
cylindrical or other shaped metallic blades (6) which catch the wind and cause the
revolution of the apparatus. m is the cover to keep off the snow. In Sheet 2 a
plan of the driver with the cover removed is shown. The driver is rigidly fixed to
the top of the shaft. In the interior of the driver is a metallic cylinder (e) for
holding oil to lubricate the shaft. This is filled with oil from an orifice on the top
of the cover and exudes from a small hole on to the shaft a little above the upper
bearer d. From thence the oil trickles down the shaft to lubricate the lower
bearer d

page_text: B (Sheet 1). The shaft. This is made of steel or other metal and is 30 inche
long by inch thick on elevation but may be of any size to suit work required.
It rests on the lower bearer d. At or near the end of the shaft is fixed the screw
propeller.
C. Propeller. This is made of brass or other metal and may have two or four
or any number of blades, and is for the purpose of creating when it revolves an
upward current of air.
D. Cage. This is composed of two bearers, an upper (d) and a lower (d') made
of brass or other metal, to support the shaft, and four, or other number, of bars
of iron or other metal, flat or round, bent and fixed as shown in elevation (e. c.)
(Sheet 1). The bends or shoulders at f rest on chimney can or air funnel. The
lower bearer (d¹) on which so much depends for the support and smooth action of
the movable part of the apparatus is shown in section (Sheet 1). 9 is a movable
screw for adjustment made of steel or other metal and h is a disc of steel or other
hard metal on which the point of the shaft revolves. This disc may be done away
with and the shaft made to rest directly on the end of the screw g. i. i are two
circular metallic bands to bind the cage firmly together. D³ (Sheet 2) is a plan
of the lower end of the cage. This form of the cage may be modified by using a
metallic tube instead of the aforesaid metallic bars. ; (Sheet 1) is an oil cup
which retains the oil as it trickles down the shaft.
E is the circular metallic plate which in elevation is 13 inches in diameter with
edges turned down inch but which may be of any suitable size.
On Sheet 3 is shown the elevation of the framework of louvre plates, and on
Sheet 2 the plan. kk are metallic bands to which the louvre plates 1. L. are
fastened, and m¹ is the cover. p. p. are pillars made of wood or metal to stiffen the
framework. The framework rests on the brackets n. n. to which it is fastened by
the screws o. 0.
F is the base for fixing to the roof.
It is to be understood that I do not limit myself exactly to the particular
arrangement and construction of apparatus herein before described with reference
to the accompanying sheets of drawings, but that my invention also includes, that
the screw propeller may be reversed so as to send a current of air down the air
funnel which would then act as a down-cast shaft for the supply of fresh air: that
the circular metallic plate instead of being fixed to the cage, may be fixed to and
form part of the revolving driver: that ball or glass bearings for the shaft may be
employed if greater smoothness of motion be desired: and further, that a jet of
steam or water may be led by a suitable arrangement to play upon the driver in
addition to or in lieu of the pressure of the wind.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is
First-That the novelty of my apparatus consists in creating in the chimney
or air funnel an upward current of air by the revolution, caused by the wind, of a
screw propeller in the said chimney or air funnel, which, besides creating a vacuum,
and thus assisting the upward draught from below, sends an upward current of air,
which resists or checks any wind that would have a tendency to blow down the
chimney or air funnel.
Second: By reversing the screw propeller and thus forming a down-cast or inlet
funnel for the supply of fresh air.
Third: The arrangement and construction of the parts of the apparatus called
the driver, and the cage, with its bearers and circular metallic plate, the latter of
which throws the wind by reflection on to the blades of the driver, prevents the
wind and rain from blowing directly down the chimney or air funnel, and prevents
the smoke from entering the driver and choking its blades with soot.
Dated this 21st day of May 1892.