IMPROVEMENTS IN CHIMNEY TOPS OR VENTILATORS
Year: 1881

page_text: LETTERS PATENT to William Chrystal, of Commercial Road, in the County
of Middlesex, for an Invention of "IMPROVEMENTS IN CHIMNEY TOPS OR
VENTILATORS."
PROVISIONAL SPECIFICATION left by the said William Chrystal at the
Office of the Commissioners of Patents on the 31st May 1881.
WILLIAM CHRYSTAL, of Commercial Road, in the County of Middlesex.
"IMPROVEMENTS IN CHIMNEY TOPS OR VENTILATORS."
My Invention relates to an improved ventilating top for chimneys and shafts
so constructed that the wind in blowing against it from any direction is caused to
induce upward currents in the chimney or shaft.
My improved chimney top is constructed of a number of upright plates placed
radially around a central thoroughfare corresponding to that of the flue, and
having fixed between each two of them a number of upwardly inclined deflecting
plates or louvres placed one above the other, the intervals or passages between
them leading to the central thoroughfare.
These deflectors present their inclined surfaces to the wind on all sides of the
chimney top or ventilator, and they may be at uniform heights on all sides, in
which case the top would resemble a series of superposed conical or pyramidal
deflectors united by upright plates. The wind in striking against the deflectors
and the radial plates which support them is directed into the central thoroughfare
in an upwardly inclined direction, thereby promoting a strong updraught in
the flue.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Chrystal in the Great Seal Patent Office on the 29th
November 1881.
WILLIAM CHRYSTAL, of Commercial Road, in the County of Middlesex.
“IMPROVEMENTS IN CHIMNEY TOPS OR VENTILATORS,”
My Invention relates to an improved chimney top or ventilator for chimneys
and shafts so constructed that the wind in blowing against it from any quarter
is caused to induce upward currents in the chimney or shaft.
My improved chimney top or ventilator is constructed of a number of upright
plates placed radially around a central thoroughfare corresponding to that of the
flue, and having fixed between each two of them a number of upwardly inclined
deflecting plates or louvres placed one above the other, the intervals or passages
between them leading upwards into the central thoroughfare. These deflectors
present their inclined surfaces to the wind on all sides of the chimney top or
ventilator, and they may be at uniform heights on all sides, in which case the top
would resemble a series of superposed conical or pyramidal deflectors united by
upright plates. The wind in striking against the deflectors and the radial plates
which support them is directed into the central thoroughfare in an upwardly
inclined direction, thereby promoting a strong up-draught in the flue. My
improved chimney top or ventilator also has the advantage of preventing down
draughts on the flue, for should a downwardly directed current of air strike the
top of the ventilator and enter the central roughfare it would readily escape
through the inclined passages between the deflectors and louvres, and carry the
smoke with it, and would not cause any down draught in the flue itself. This
chimney top or ventilator has no movable parts to get out of order, and can bo
readily cleaned by the swcep's brush.
.
Figure 1 is an elevation of the improved chimney top or ventilator half in section
on line a, a, Figure 2, which is a plan view of the same.
This improved chimney top or ventilator is constructed preferably of sheet metal
plates (galvanized iron or zinc) united by rivetting or soldering. It may be of
hexagonal or other polygonal figure in plan, and is constructed of as many series
of upwardly inclined deflecting plates or louvres a, as the chimney top has sides
arranged around a central thoroughfare c, the plates of each series being set ono
above the other at a short distance apart, and fixed between and to upright ribs
or plates b located at the angles of the polygonal figure and set edgewise or radially
to the central thoroughfare c, which is about the same size or rather larger than
the chimney or shaft on which the top or ventilator is to be placed. These upright
ribs or plates b rise from a plato & fixed upon a short tubular foot e which is to
be fixed on the chimney or shaft in the usual way, and the ribs bare braced
together by the inclined deflectors or louvres a, and also by a band at top, the
whole forming a rigid structure, presenting on all sides upwardly directed passages
loading into the central shaft through which the wind enters.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Lotters Patent is,-
The improved chimney top or ventilator constructed of series of upwardly
inclined deflectors or louvres fixed at intervals between upright ribs or plates

page_text: arranged around a central passage and forming an open structure, substantially
as herein described and shewn in the Drawings for the purpose specified.
In witness whereof, I, the said William Chrystal, have hereunto set my hand
and scal, this Twenty-ninth day of November, in the year of our Lord
One thousand eight hundred and eighty one.
WILLIAM CHRYSTAL. · (L.S.)