AN IMPROVED GAS TAP
Year: 1877

page_text: LETTERS PATENT to James Longshaw, of Warrington, in the County of Lan-
caster, for the Invention of "AN IMPROVED GAS TAP."
Sealed the 9th April 1878 and dated the 19th December 1877
PROVISIONAL SPECIFICATION left by the said James Longshaw at the Office
of the Commissioners of Patents on the 19th December 1877.
JAMES LONGSHAW, of Warrington, in the County of Lancaster.
GAS TAP."
"AN IMPROVED
The object of this Invention is to construct a tap for gas or other fluids at low
pressure, which will not allow of the possibility of the escape of gas, and will not be
liable to set fast.
The principle of construction of my improved tap is to separate the inlet and the
outlet passages by means of a descending division plate (by preference vertical),
and to open or close communication between the two by lowering or raising the
level of a small quantity of mercury contained in the lower part of a cup or vessel
placed immediately below the two openings.
It will be evident that as the level of the mercury is lowered, and falls below the
bottom of the partition or division plate, communication will be made between the
inlet and outlet passage, and the gas will be permitted to flow, and, on the contrary,
as soon as the level of the mercury is raised the lower end of the partition or
division plate dips into the same, and communication between the inlet and outlet
is shut off.
The exact form and details of my improved tap are capable of considerable
variation without departing from the principle of its construction, as above
mentioned, and the method of raising and lowering the level of the mercury may be
effected in a variety of ways; but for the sake of illustration I will here describe one
of its simplest forms.
The inlet and outlet passages are formed by a short vertical tube, with a vertical
partition or division plate in the centre, the inlet passage being on one side of the
division plate, and the outlet passage on the other.

page_text: The lower end of the tube is open, and projects a short distance beyond the
partition or division plate. On this lower end of the tube is fitted a cup capable of
sliding a short way telescopically on the same, and provided beneath with a cock or
thumb-piece.
A spiral slot is made in the side of this cup, in which works the head of a screw
fixed in the tube, so that by turning the cup partially round in either direction the
cup is caused to rise or fall on the end of the tube. In this cup is placed a quantity
of mercury, into which the lower end of the tube dips, but the level of which does
not reach the partition or division plate.
It will be evident that the gas can now pass from the inlet to the outlet, but
cannot leak between the end of the tube and the cup, as it cannot pass through the
mercury. As soon however as the cup is raised slightly by partially turning round
the cock or thumb-piece, the level of the mercury therein reaches the lower end of
the partition, and effectually closes communication between the inlet and outlet
passages.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Longshaw in the Great Seal Patent Office on the 18th June
1878.
JAMES LONGSHAW, of Warrington, in the County of Lancaster.
GAS TAP."
"AN IMPROVED
The object of this Invention is to construct a tap for gas or other fluids at low
pressure, which will not allow of the possibility of the escape of gas, and will not be
fiable to "set fast."
"
The principle of construction of my improved tap is to separate the inlet and the
outlet passages by means of a descending partition division plate (by preference
vertical), and to open or close communication between the two by lowering or
raising the level of a small quantity of mercury contained in the lower part of a cup
or vessel placed immediately below the two openings.
It will be evident that as the level of the mercury is lowered, and falls below the
bottom of the partition or division plate, communication will be made between the
inlet and the outlet passages, and the gas will be permitted to flow, and, on the con-
trary, as soon as the level of the mercury is raised the lower end of the partition or
division plate dips into the same, and communication between the inlet and outlet
is shut off.
The exact form and details of construction of my improved tap are capable of
considerable variation without departing from the principle of its construction as
above mentioned, and the method of raising and lowering the level of the mercury
may be effected in a variety of ways; but for the sake of illustration I will here
describe one of its simplest forms, the construction of which will be readily under-
stood on reference to the annexed Drawing, in which Fig. 1 is an elevation, Fig. 2
a vertical section, and Fig. 3 a horizontal section of the same.

page_text: The inlet and outlet passages are formed by a short vertical tube a, a, with a
vertical partition or division plate b, b, in the centre, the inlet passage c, c, being on
one side of the division plate b, b, and the outlet passage d, d, on the other.
The lower end of the tube a, a, is open, and projects a short distance beyond the
partition or division plate b, b. On this lower end of the tube is fitted a cup e, e,
capable of sliding a short way telescopically on the same, and provided beneath with
a cock or thumb-piece f, f.
A spiral slot g, g, is made in the side of this cup, in which works the head of a
screw h fixed in the tube a, a, so that by turning the cup e, e, partially round in either
direction the cup is caused to rise or fall on the end of the tube a, a.
In this cup
e, e, is placed a small quantity of the mercury, into which the lower end of the tube
a, a, dips, the level of which does not reach the partition or division plate b, b.
It will be evident that the gas can now pass from the inlet c, c, to the outlet d, d,
but cannot leak between the end of the tube a, a, and the cup e, e, as it cannot pass
through the mercury. As soon however as the cup e, e, is raised slightly by partially
turning round the cock or thumb-piece f. f, the level of the mercury therein reaches
the lower end of the partition b, b, and effectually closes communication between
the inlet and outlet passages c, c, and d, d.
Having now described the nature and object of my said Invention, together with
the manner in which the same is to be or may be performed or carried into practical
effect, I wish it to be understood that I claim as my Invention, the novel construc-
tion of tap for such purposes, wherein the communication between the inlet and
outlet is opened or closed by means of mercury, substantially in the manner herein-
before particularly set forth.
In witness whereof, I, the said James Longshaw, have hereunto set my hand
and seal, this Thirteenth day of June, in the year of our Lord One thousand
eight hundred and seventy-eight.
JAMES LONGSHAW. (L.S.)