IMPROVEMENTS IN THE VALVES USED IN CLOSING THE TUBES OF ATMOSPHERIC RAILWAYS
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
FROUDE, of Darlington, in the County of Devon, Civil Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Fifth day of January,
One thousand eight hundred and forty-eight, in the eleventh year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
William Froude, my exors, admors, and assigns, Her especial licence, full
power, sole privilege and authority, that I, the said William Froude, my exors
admors, and assigns, or such others as I, the said William Froude, my exors,
admors, or assigns, should at any time agree with, and no others, from time
to time and at all times during the term of years therein expressed, should and
lawfully might make, use, exercise and vend, within England, Wales, and the
Town of Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN THE VALVES
USED IN CLOSING THE TUBES OF ATMOSPHERIC RAILWAYS;" in which said Letters
Patent is contained a proviso, that I, the said William Froude, shall cause a
particular description of the nature of my said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand and
seal, to be inrolled in Her said Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part
recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William Froude, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had to
the Drawing hereunto annexed, and to the figures and letters marked thereon,
that is to say:-
My Invention consists of improvements in the valves used in closing the
tubes of atmospheric railways; and in order that the same may be fully under-
stood, I will proceed to describe the Drawing, which represents part of a tube
of an atmospheric railway in section, having my Invention applied thereto.
a, a, is the upper portion of the tube; throughout its upper side runs a longi-
tudinal opening, which allows the passage of the arm plate or bar connecting
the piston gear with the piston carriage. On each side of the opening the
upper surface of the tube is formed into the seat of the valve, and the seat of
the valve is bounded on each side by a perpendicular flange, parallel to the
opening in the tube.
The foot of each flange, where it meets the seat of the valve, is rounded off
into it by a circular line, forming a slight sinkage or recess in it. b, b, aro
plates of rolled or cast iron, each about eight inches in length, and of such a
width that, with one edge abutting against the foot of the flange and resting in
the hollow above mentioned, the other edge nearly reaches the centre line of
the opening in the tube. The portions of plate which cover the opening in
the tube are cranked downwards so as to fall into the opening and complete
the cylindrical form of the interior of the tube, and to form a recess or hollow
along their upper surface. A series of these plates placed opposite one another
cover the seat of the valve throughout. c, c, are plates of rolled or cast
iron, of the same length, with the plates 6, 6, and rivetted to them with their
ends matching; each pair of plates will require two rivets, videlicit, a rivet
about one inch from each end. The ends and angles of b, b, on the upper
surface, and of c, c, on the under surface must be chamfered and rounded off,
so as to render them incapable of cutting; d, d, are continuous sheets of
vulcanized india-rubber, having throughout an upper surface of canvas.
They entirely cover the plates b, b, and are firmly held between b, b, and c, c,
by the pressure of the rivets, and they extend up the flanges and round their
upper angles. Along the centre line of the opening they are thickened out
into substantial pads of the same material, which rest in the recess or
hollow of the upper surface of the plates b, b. When the valve is placed as
shewn in the Drawing, the pads are strongly pressed each against the other,
and to secure this pressure they are of such a form and dimension that, if

page_text: $2
released from pressure, each will extend itself outwards, so as to be about
one-sixteenth of an inch wider than when under pressure. And they are so
arranged with reference to the hinges or parts on which the two parts of
the valve turn, as hereafter described, that when the valve rests upon its seat
the centre of the pressure which they exert against each other shall be below
straight line drawn through the centres of the hinge motion. e, e, are bars
of rolled iron following the whole length of the tube; they may be in lengths
of from ten to fifteen feet; they are tightly strained against the canvas
covering the vulcanized india-rubber, which intervenes between them and the
flanges, by the bolts and nuts f, f, which should be placed at intervals of from
twelve to fifteen inches, the bars and the flanges being provided with proper
holes at these intervals.
The small fillets or projections on the inner surfaces of the bars serve to
indent the rubber, and press it more forcibly against the flanges so as to prevent
the passage of air.
The lower edges of the bars press the canvas and rubber against the heels
of the plates b, b, and retain them in their proper position when lifted along
the line of opening, and the heels of the plates thus held become hinges on
which the valve turns in opening, and the retaining edges of the bars are
rounded off so that they may not cut the canvas and rubber where they exert
their pressure.
To prevent the rusting of the plates and bars I recommend that they should
be galvanised or well painted; the upper surface of the canvas should also be
painted.
The valve will be lifted and opened, to allow the passage of the arm plate,
by a series of wheels preceding it and affixed to the piston gear inside the
tube. I recommend that not less than five wheels be used for the purpose,
the foremost wheel being about nine feet in advance of the arm plate, and the
rest following at intervals of two feet from centre to centre. The wheels must
be of sufficient breadth on their circumference to press in lifting against both
divisions of the valve, and the upper surface of the wheel nearest the arm
plate must be of sufficient elevation to lift the valve nearly to an angle of sixty
degrees, and the other wheels must be so arranged that the edge of the valve
thus lifted by them and resting on them shall assume a wave-like form. After
the passage of the arm plate the valve must be allowed to drop, resting on
a similar series of wheels. In dropping, the projecting edges of the pads of
rubber will meet before the valve reaches its seat, and would retain it elevated
in an angular position, as shewn on the Drawing in red lines, but finally a
pressing or closing wheel must run along the upper surface of the valve

page_text: following the wheels within the tube, and press it down until it reaches its seat.
The edges of the pads will thus again be pressed strongly against each
other and present an air-tight or nearly air-tight junction along the line of
opening and closing, and the centre of the pressure thus produced being below
the level of the points on which the valve hinges, the elasticity of the pads
will not tend to lift the valve again, but, on the contrary, will retain it firmly
bedded on its seat.
The arrangement which I have above described is that which I consider the
best method of constructing and applying a valve according to my Invention,
but I do not confine myself thereto so long as the peculiar principle of
construction and use be retained, and the materials of which the parts of
the apparatus are composed are suitable to their proper action.
That which I consider to be the essential condition and peculiarity of my
Invention, and which I claim, is the constructing and applying a valve or
diaphram of greater width than the boundaries of the seat in which it is to
rest, and in such manner that the edge or edges of the diaphragm or valve
along the line or lines of opening shall be so formed that when strongly
pressed the line or lines of opening shall be closed and rendered air-tight, or
nearly air-tight, by straightening or comparatively straightening that bent or
angular form of cross section which the valve is to be made capable of as-
suming when free, the excess of width which the diaphragm or valve
endeavours to resume being provided for, either by sufficient extensibility in
the seat of the valve or sufficient compressibility in the parts of the valve
itself, or by both of these methods combined. And further, it is essential that
the point of principal flexure in straightening the valve shall be carried either
beyond the straight line (joining the centres of pressure at the sides or abut-
ments of the diaphragm), or so near to it that the elasticity brought into action
by the straightening shall tend to keep the same closed, or otherwise not be
able to cause the valve to resume its angular or bent form.
And I would, in conclusion, state that the construction and arrangement of
parts of the valve according to my Invention may be varied, so long as the
conditions above given are fulfilled.
In witness whereof, I, the said William Froude, have hereunto set my
hand and seal, this Fifth day of July, in the year of our Lord One
thousand eight hundred and forty-eight.
WILLIAM
(L.S.) FROUDE.

page_text: AND BE IT REMEMBERED, that on the Fifth day of July, in the year of
our Lord 1848, the aforesaid William Froude came before our said Lady the
Queen in Her Chancery, and acknowledged the Specification aforesaid, and all
and every thing therein contained and specified, in form above written. And
also the Specification aforesaid was stamped according to the tenor of the
Statute made for that purpose.
Enrolled the Fifth day of July, in the year of our Lord One thousand eight
hundred and forty-eight.