AN IMPROVED VENTILATOR
Year: 1867

page_text: COMPLETE SPECIFICATION filed by the said Johu Thomas Kershaw
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 21st December 1867, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, JOHN
THOMAS KERSHAW, Surveyor, of No. 90, St. Paul's Road, Islington, in the
County of Middlesex, send greeting.
WHEREAS I am in possession of an Invention for "AN IMPROVED
VENTILATOR,"
," 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
declaro 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:-
My Invention is intended to be fixed into the chimney of a room that is to
be ventilated.
It consists of the following parts, the first two of which are shewn in the
annexed Drawings:-First, the case; second, the valve which works in the
case; these are the essential parts; third, an ornamental front, which is
merely accessory.

page_text: The case marked Z, in Figs. 1, 2, 3, consists of a metal box without front
or back, the sides of which need not be more than one-eighth of an inch
thick. The case has a pulley fixed on it as shewn. It is most convenient to
make this case of the dimensions 8 inches by 8 inches by 8 inches internal
measurement, but sometimes it is convenient to vary these dimensions, or
these proportions, or both, and I therefore claim to vary them when necessary.
I make the under side of this case to project as shewn in the Drawings, in
order to afford a support for the hinge.
The valve consists of several parts:-The first is a piece of rectangular
sheet iron bent at a right angle into two unequal parts, on this right angle the
valve when fitted into the case turns as on a hinge. The larger part "a" of
this piece of rectangular sheet iron has very nearly the same area and dimen-
sions as the case has in cross section. Around the edges of this part "a" I
secure strips of felt, so that when the valve is in its place and open the space
between the edges of this part "a" and the inside of the case may be as
nearly air-tight as possible. In this part "a" a circular hole as large as
possible is cut. Into this hole the larger end of a truncated hollow cone or
pyramid (by preference a cone) "6" is securely fixed so that the smaller end
may be towards the chimney as shewn in Fig. 1. The height of this cone
is such that when the part
"
a
"
turns on the right angle above named the
cone will pass into the case. The diameter of the smaller end of the cone I
make about half the diameter of the larger end, but I do not confine myself
to this proportion, but claim to vary it as circumstances may require. I
continue the smaller part "c" of the rectangular piece of sheet iron by
means of a skeleton framework d, f, e, g, Fig. 3. To the under side
of the piece I hinge what I call a subvalve h, the dimensions of which
should be such that where the subvalve is shut it shall entirely cover
the open space included between the internal edges of c, d, f, e. To
the under side of this subvalve I suspend by means of a short chain a
.weight. I prevent this subvalve falling too far open by means of a short
.chain, one end of which is fixed to the subvalve, and the other to the piece 9,
or to any other convenient part of the skeleton framework.
I provide
wings, k, which slide on the upper part of the skeleton frame, and
which when slid out to the required extent may be secured in that position by
means of the screws 1, l. These wings are not absolutely necessary in every
case, for should it happen that the flue of a chimney to which one of these
ventilators is to be applied is very little wider than the width from the outer
edge of the piece d to the outer edge of the piece e, then the wing
pieces k, k, will not be required. Over the pulley I place a piece of

page_text: b
chain, one end of which is fixed to the skeleton frame, and the other end of
which passes through the hole in the top of the case into the case, and is then
secured to a cord. The cord is continued through the front of the case. By
this cord the valve is opened, closed, or regulated at pleasure. The valve is
secured to the case at the part shewn in the Drawings in such a way that it
can turn on the right angle as a hinge; I prefer to secure it by means of a
slight rod of iron m bearing on the sides of the case in such manner that,
if necessary, I can at pleasure detach the valve from the case. When the
valve is fitted into the case and the case fitted into the chimney of any room
which it is desired to ventilate, the action of this apparatus is as follows:-
On releasing the cord (the valve being closed) from the fastening to which it
is secured, and this fastening may be any one convenient, the weight of the
parts c, d, e, f, g, h, i, overbalances that of the parts a, b, and causes the
entire valve to assume the position as shewn in Figs. 1 and 8, when the part a
becomes vertical, the axis of the cone 6 horizontal or nearly so, the skeleton
frame horizontal, and the subvalve open and slightly inclined downwards. In
this position the greater part of the area of the flue is obstructed. It is neces-
sary that the skeleton frame and the part c together shall have such a length
that when the valve is fixed in the case and opened the outer edge of the part
f shall nearly or quite touch the back of the flue and the outer edges of the
parts & and e, or the outer edges of the wings k, k, as the case may be, shall
nearly touch the sides of the flue. The consequence of this obstruction will
be that the chimney being cut off from a full supply of air by way of the fire-
grate will draw air through the hollow truncated cone with a velocity so great
as to prevent any smoke escaping from the chimney through the cone. It is
because most flues have a width greater than the width I make the skeleton
frame that I provide the wings so that they being extended may entirely
obstruct the flue from side to side. In fixing the case into the chimney breast
it is requisite that it be allowed to oversail to the extent of one or two inches
so that the wings and skeleton frame may, when the valve is closed, have a
fair bearing against the edges of the case, and so make the entire apparatus
smoke-tight when the valve is closed, as the felt round the edges of the part a
will make it smoke-tight when the valve is open. The subvalve is provided
that in the event of soot falling down the chimney the soot may either at once
slide down the subvalve into the grate or else be thrown down at the moment
when the valve is closed. The valve may be made of thin sheet iron, the
pieces d, e, f, being slightly stouter than the remaining parts. The orna-
mental front being merely accessory and not essential, requires no description
and is not shewn on the Drawings.

page_text: I wish it to be particularly understood that I do not confine myself to the
dimensions shewn on the Drawings or described above, but what I claim as
my Invention is, the subvalve h, and the skeleton frame d, f, e, to which
it is fixed; also the adoption of a hollow truncated cone or pyramid 6 in
combination with a plate a, also that combination of the part a, the hollow
truncated cone or pyramid b, the part c, the skeleton frame d, f, e, g, and
the subvalve h, by which the entire valve as described above and as shewn in
the annexed Drawings is produced.
In witness whereof, I, the said John Thomas Kershaw, have hereunto
set my hand and seal, this 21st day of December, in the year of our
Lord One thousand eight hundred and sixty-seven.
JOHN THOS. KERSHAW. (L.S.)
This is the Specification referred to in the Declaration of John Thos. Kershaw
declared before me this 21st day of December 1867.
S. WARD.