CERTAIN IMPROVEMENTS IN THE ARRANGEMENT OF "TRAP-DOORS," OR " AIR-DOORS," AND THEIR CASES, IN THE WORKINGS OR PASSAGES IN MINES, WHEREBY THE EFFICIENT VENTILATION IS MAINTAINED, WHICH SAID IMPROVEMENTS ARE ALSO APPLICABLE IN OTHER SIMILAR SITUATIONS
Year: 1856

page_text: LETTERS PATENT to George Forster, of Standish, near Wigan, in the
County of Lancaster, Colliery Viewer, for the Invention of "CERTAIN
IMPROVEMENTS IN THE ARRANGEMENT OF "TRAP-DOORS," OR " AIR-DOORS," AND
THEIR CASES, IN THE WORKINGS OR PASSAGES IN MINES, WHEREBY THE
EFFICIENT VENTILATION IS MAINTAINED, WHICH SAID IMPROVEMENTS ARE ALSO
APPLICABLE IN OTHER SIMILAR SITUATIONS."
Sealed the 21st October 1856, and dated the 23rd April 1856.
PROVISIONAL SPECIFICATION left by the said George Forster at the
Office of the Commissioners of Patents, with his Petition, on the
23rd April 1856.
I, GEORGE FORSTER, of Standish, near Wigan, in the County of Lancaster,
Colliery Viewer, do hereby declare the nature of my said Invention for
"CERTAIN IMPROVEMENTS IN THE ARRANGEMENT OF TRAP-DOORS,' OR 'AIR-
DOORS, AND THEIR CASES, IN, THE WORKINGS OR PASSAGES IN MINES, WHEREBY
THE EFFICIENT VENTILATION IS MAINTAINED, WHICH SAID IMPROVEMENTS ARE
ALSO APPLICABLE IN OTHER SIMILAR SITUATIONS, to be as follows:-
My improvements consist, first, in so arranging the "traps" or "air-doors"
in the passages of mines, that they shall allow of the passing of loads or
wagons to and fro without permitting any improper rush or current of air
to pass through the said passages and interfere with the ventilation, as the
opening of the ordinary traps or doors at present allows. I arrange or place

page_text: double doors at suitable distances apart in the workings or passages, and so
connected with each other, by means of a connecting rod or bar combined with
suitable levers, that the opening of one door will necessarily close the other, or
that next behind it, and thus prevent the rush or current of air passing directly
through both doors, as the second door cannot be opened until the first door is
effectually closed. The cases in which these doors are hung or arranged
are extended on the sides opposite to the hinges in the form of the arc
described by the swing of the door (which forms the radius), so as to keep the
door almost air-tight whilst opening, and leaving only sufficient room for the
wagon, &c. to pass into the space between the first and second door; the
further passage of the wagon, &c. will next open the second door, leaving
the first closed behind the wagon, and thus proceed onwards as required. In
instances where there are double ways or trams through the workings or
passages, the doors (instead of being hung upon hinges) turn upon pivots in
the centre between the two lines of way, and have the same provision of the
extension of the casing, but in this instance the arc described by the edges of
the door (swinging both ways) will be equal on either side, so as to keep the
door nearly air-tight in either direction of its swing. This arrangement being
self-closing, dispenses with attendants in mines, called "trappers."
Secondly, these improvements are equally applicable in other similar
situations where it is desirable to prevent an outer current of air from passing
directly into the interior of the passage or chamber, and interfere with the
ventilation, such as on opening the outer doors of churches, law courts, and
other large public or private apartments.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Forster in the Great Seal Patent Office on the
23rd October 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
FORSTER, of Standish, near Wigan, in the County of Lancaster, Colliery
Viewer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of April, in the year of our Lord
One thousand eight hundred and fifty-six, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said George Forster, Her especial license that I, the said George Forster, my
executors, administrators, and assigns, or such others as I, the said George

page_text: Forster, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "CERTAIN IMPROVEMENTS IN THE
ARRANGEMENT OF "TRAP-DOORS," OR "AIR DOORS," AND THEIR CASES, IN THE WORK-
INGS OR PASSAGES IN MINES, WHEREBY THE EFFICIENT VENTILATION IS MAINTAINED,
WHICH SAID IMPROVEMENTS ARE ALSO APPLICABLE IN OTHER SIMILAR SITUATIONS,"
upon the condition (amongst others) that I, the said George Forster, by an
instrument in writing under my band and seal, should particularly describe and
ascertain the nature of, the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal. Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said George Forster, do hereby declare the
nature of my said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement
and accompanying Drawings (that is to say):-
My improvements. consist, first, in so arranging the "traps" or "air-doors"
in the passages of mines that they shall allow of the passing of loads or waggons
to and fro without permitting any improper rush or current of air to pass
through the said passages, and interfere with the ventilation of the mine, as the
opening of the ordinary traps or doors at present allows. I arrange or place
double doors at suitable distances apart in the workings or passages, and so
connected with each other, by means of a connecting rod or bar combined with
suitable levers, that the opening of one door will necessarily close the other, or
that next behind it, and thus prevent the rush or current of air passing directly
through both doors, as the second door cannot be opened until the first is
effectually closed. The cases in which these doors are hung or arranged are
extended on the side opposite to the hinges in the form of the arc of the
circle described by the swing of the door (which forms the radius), so as to
keep the door almost air-tight whilst opening, and leaving only sufficient room
for the wagon, &c. to pass; the further passage of the wagon, &c. will next open
the second door, leaving the first closed behind the wagon, and those proceed
onwards as required. In instances where there are double ways or trams
through the workings or passages, the doors (instead of being hung upon
hinges) turn upon pivots in the centre between the two lines of way, and have
the same provision of the extension of the casing, but in this instance they are
described. by the edges of the door (swinging both ways) will be equal on

page_text: either side, so as to keep the door nearly air-tight in either direction of its
swing. This arrangement being self-closing, dispenses with attendants -in
mines called "trappers."
Secondly, these improvements are equally applicable in other similar
situations where it is desirable to prevent an outer current of air from passing
directly into the interior of the passage or chamber and interfere with the.
ventilation, such as on opening the outer doors of churches, law courts, and
other large public or private appartments.
In order that this Invention may be more readily understood, I have attached
to these Presents a Sheet of Drawings, made upon a scale of about a quarter of
an inch to a foot (when applied to the passages of mines, as exhibited), and
having similar letters of reference marked upon corresponding parts of the
mechanism through the several Figures illustrated.
Fig. 1 is a plan view of the doors and casings (supposing the roof of the
passage to be removed), shewing the position of the short levers and rod
connecting them.
"
.
Figs. 2 and 3 are also plan views (having the roof removed); Fig. 2 ex-
hibiting one method of applying ropes or chains and pulleys for the same
purpose as the levers and rod in Fig. 1. Fig 3 illustrates the mode in which
the arrangement of doors turning on pivots at the centre is applied to the
passages of mines in places where double lines of way or "trains are
employed; these doors are shewn connected by means of levers and rods in
lieu of ropes, &c., as being more practicable, though the former is equally
applicable; this Figure also exhibits the relative position of the doors by the
dotted lines, one door being shewn full open and the next behind it closely shut,
as would take place by the passage of a load or waggon.
In Fig. 1, a, a, is the passage or working of the mine, through which is laid
a single line of way or "train" b, b; c, c, are the double doors, turning upon a
hinge and having their edges fitting closely in the casings d, d; the levers e, e,
are attached to the doors in a suitable position, either upon the centre or
hinges, or otherwise, and are connected together by the rod f, by which con-
nection both doors are caused to move in the required direction simultaneously.
In Figs. 1, 2, and 3, 9, 9, 9, are counterbalance weights applied to one
of each set of doors, which are equal to the weight of the air current pressing
against the doors, and facilitate the opening of such doors.
In Fig. 2, h is the rope, chain, or band connecting the two doors, and used
instead of the levers and rod; this rope, &c. passes along guide pulleys į,
which may be situated in any convenient position, either between the doors or
outside, according to the direction in which the same may be required to open
.

page_text: Fig. 3 shews a double "tramway" 6, 6', comprising an "up" and "down"
line, and the doors c, c¹, turning upon a pivot k, and are connected by a double
set of levers and rods, as forming a better connection and more even motion
than where only one set is employed. The operation of this apparatus will be
better understood by referring to Fig. 3 of the Drawing, and the following
explanation thereof:-Supposing a load to be entering the door c from left to
right, in the direction of the arrow, the door will be required to be opened by
hand, and will remain in the position as indicated by the dotted lines (clear of
its casing) until the load reaches the door c', which may be opened by pressure,
and thus close the door c by the levers and rods, and so on, through all
the doors arranged throughout the passage of the mine; and the same opera-
tion would apply if the load entered on the other line from right to left. The
casings d, d, may be so extended both ways, and formed as to keep the door
air-tight in a great part of its motion, allowing only sufficient room for the
passing of a waggon, &c., or they may be confined to the necessary smaller
segment, as illustrated in Figs. 1, 2, 8.
Having now described the nature and object of my said Invention, together
with a method of practically carrying the same into operation, I wish it to be
distinctly understood that I claim the arrangement of double air-doors in mines,
in combination with the novel door casings d, d, being nearly air-tight) whether
such doors be turned upon a hinge at the end, or a pivot placed in the centre,
and whether the said doors be connected by ropes, bands, chains, &c., or levers
and rods, or other equivalent means, as herein-before described and set forth,
and fully illustrated in the accompanying Drawings.
In witness whereof, I, the said George Forster, have hereunto set my
hand and seal, this Twenty-second day of October, in the year of our
Lord One thousand eight hundred and fifty-six.
GEORGE FORSTER. (L.S.).