IMPROVEMENTS IN CHIMNEY CAPS, OR TERMINALS, AND VENTILATORS
Year: 1877

page_text: LETTERS PATENT to Christopher John Gibson, of Canal Road, Wharfdale Road,
King's Cross, in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN CHIMNEY CAPS, OR TERMINALS, AND VENTILATORS."
Sealed the 1st September 1877, and dated the 7th March 1877.
PROVISIONAL SPECIFICATION left by the said Christopher John Gibson at
the Office of the Commissioners of Patents on the 7th March 1877.
CHRISTOPHER JOHN GIBSON, of Canal Road, Wharfdale Road, King's Cross, in
the County of Middlesex. "IMPROVEMENTS IN CHIMNEY CAPS, OR TERMINALS, AND
VENTILATORS."
The Invention has for its object improvements in chimney caps, or terminals, and
ventilators. For this purpose I form the main portion of the cap, or terminal, or
ventilator, of a series of spiral blades or spiral louvre boards, arranged in the form
of a many-bladed screw, the blades of which are connected together at their peri-
pheries by means of concave uprights, so arranged that the concavity of such
uprights shall catch the wind and thereby give rotary motion to the above-described
portion of the cap, terminal, or ventilator.
The part above described is mounted with capability of rotating on a vertical rod
or axis, carried by cross bars fixed into a cylindrical part at the lower end, and the
top is finished by means of a hollow cone or cylinder, which connects the blades and
uprights together. The openings or spaces between the spiral blades or louvre
boards communicate with the space in the centre of the cap, terminal, or ventilator.
Thus rotary motion is given to the many-bladed screw by the wind, whereby a
current of air or smoke is induced up the flue or ventilating shaft, and in the event
of wind blowing down the cap, terminal, or ventilator, the tendency is to accelerate
the rotary motion, and thereby increase the upward current through the flue..

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Christopher John Gibson in the Great Seal Patent Office on the 7th
September 1877.
CHRISTOPHER JOHN GIBSON, of Canal Road, Wharfdale Road, King's Cross, in
the County of Middlesex. "IMPROVEMENTS IN CHIMNEY CAPS, OR TERMINALS, AND
VENTILATORS."
The Invention has for its object improvements in chimney caps, or terminals, and
ventilators. For this purpose I form the main portion of the cap, or terminal, or
ventilator, of a series of spiral blades or spiral louvre boards, arranged in the form
of a many-bladed screw, the blades of which are counected together at their peri-
pheries by means of concave uprights, so arranged that the concavity of such
uprights shall catch the wind, and thereby give rotary motion to the above described
portion of the cap, terminal, or ventilator.
The part above described is mounted with capability of rotating on a vertical rod
or axis, carried by cross bars fixed at the upper and lower ends, and the top is
finished by means of a hollow cone or cylinder, which connects the blades and
uprights together. The openings or spaces between the spiral blades or louvre
boards communicate with the space in the centre of the cap, terminal, or ventilator.
Thus rotary motion is given to the many-bladed screw by the wind, whereby a
current of air or sinoke is induced up the flue or ventilating shaft, and in the event
of wind blowing down the cap, terminal, or ventilator, the tendency is to accelerate
the rotary motion, and thereby increase the upward current through the flue.
And in order that my said Invention may be more clearly understood and readily
carried into effect I will proceed, aided by the accompanying Drawings, more fully
to describe the same.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is an elevation; Figure 2 is a vertical section; Figure 3 is a plan or top
view; and Figure 4 is a sectional plan, representing a chimney cap, or terminal, or
ventilator, constructed according to my Invention.
u, a, are a series of spiral blades or spiral louvre boards, arranged in the form of
a many-bladed screw, the blades of which stand by preference at an angle, and are
connected together at their peripheries by concave uprights b, so arranged that the
concavity of such uprights shall catch the wind, and thereby assist in giving rotary
motion to the above-described portion of the cap, terminal, or ventilator. At the
upper end of the part above described is a cross head a', and at the lower part a
cross head a, in which is fixed a rod or axis c, which at its lower end rests in a step
or bearing, formed in or carried by a cross head d, which is built into the brickwork
or masonry. The lower end of the rod or axis c works within a tube or chamber e,
and the cross head a¹ has a tube or chamber fixed thereto, within which is passed
the stud or axis g, which is fixed to a cross lead h¹, carried by uprights h, and bears
upon a seat or bearing formed or fixed at the bottom of the tube or chamber f.
These tubes or chambers e, f, are supplied with oil or other suitable lubricant, and
are protected at their upper ends against the entrance of rain and dirt by means of
short tubes i, as shown. The uprights h, at their lower ends, are fixed to the
cylinder, which carries the cross head d. The top is finished by means of a hollow
truncated conej, or it may be by a cylinder, which connects the blades a and
uprights b together, and the lower part consists of a cylindrical or tubular
portion k,
The openings or spaces between the spiral blades or louvre boards a communicate
with the space in the centre of the cap, terminal, or ventilator. If desirod, the
concave uprights may in some cases be dispensed with, and plain rods used in lieu
thoreof. Rotary motion is given to the many-bladed screw by the wind, whereby a
current of air or smoke is induced up the flue or ventilating shaft, and in the event
of wind blowing down the cap, terminal, or ventilator, the tendency is to accelerato

page_text: the rotary motion, and thereby increase the upward current through the flue or
ventilating shaft.
I would here remark that I am aware that chimney caps, terminals, or ventilators
have heretofore been formed with rotating screws, to assist in creating currents of
smoke or air up flues or ventilating shafts, but in such cases the screws have occu-
pied the entire sectional area of the flue or shaft in which they have been enclosed,
and rotary motion has been given to such screw by the air acting on the exterior of
another screw or rotating portion connected to such first-mentioned screw by a shaft
or axis; but, according to my Invention, the chimney cap, terminal, or ventilator is
formed of a many-bladed rotating screw, entirely exposed to the atmosphere, and
having a free space in the centre thereof, excepting the uprights and cross heads.
Having thus described the nature of my said Invention and the mode in which I
carry the same into effect, I would have it understood that what I claim is, the
improved chimney cap, terminal, or ventilator, constructed and operating in manner
substantially as herein shown and described.
In witness whereof, I, the said Christopher John Gibson, have hereunto set
my hand and seal, this Seventh day of September, in the year of our Lord
One thousand eight hundred and seventy-seven.