IMPROVEMENTS IN GUAGES POR INDICATING PRESSURE AND VACUUM
Year: 1857

page_text: by the Act.).
PROVISIONAL SPECIFICATION left by Thomas Summers at the Office
of the Commissioners of Patents, with his Petition, on the 5th February
1857.
I, THOMAS SUMMERS, of Northam Iron Works, Southampton, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN GUAGES
POR INDICATING PRESSURE AND VACUUM," to be as follows:-
This Invention relates to a novel contrivance, by which the ordinary
mercurial column steam-pressure guage can be so constructed as to be
available for indicating pressure and vacuum alternately in the same guage,
and this is effected by the alternate opening or closing of the pressure or
vacuum passage, in such a manner as when one leg of the syphon guage is
open to the pressure, the other is open to the atmosphere; but when the
opening between the pressure side and the corresponding leg is closed, it
becomes opened to the atmosphere, whilst the opposite leg is shut off from
the atmosphere and opened to the vacuum; and thus the ordinary syphon or
mercurial column used for a steam guage is made available for indicating
steam or other pressure, and also the extent or amount of vacuum existing
in a steam engine, condenser, or other vessel with which it may be connected.
The mechanical means by which I am enabled to effect this object are as
follow: I take the ordinary bent tube, of glass or other suitable material, at
the lower end or bend of which the mercury is contained, the level of which

page_text: being the same in each of the legs, and I place upon the tops or upper ends
of the legs a metal cap or box, in which the ends of the legs are secured
perfectly steam-tight, and through which there are passages radiating from
a centre, which centre is within the plug of a cock. Each of these passages
open to the top of a leg of the tube. In the same metal cap or box there are
also two horizontal passages, which radiate from the common centre or plug of
cock, and are upon the same plane as the passages communicating with the upper
ends or legs of the bent 'tube. There are two other passages at the top of the
metal cap or box which converge to the common centre or plug of the cock;
but these passages are not drilled on the same plane as the other four passages.
At the common centre from which the six passages radiate, a suitable
opening is bored at right angle therewith, into which is fitted a suitable plug,
having a milled or T headed projection, by means of which it may be turned.
This plug has an elongated opening slot or passage through it, and by turning
the plug
a suitable portion of a revolution, a direct communication may be
opened between one or the other leg of the guage tube and the atmosphere,
whilst by means of two suitably formed longitudinal spaces or passages in the
plug or tap, à communication is at the same time opened between the pressure
side and the corresponding leg of the guage tube, or between. the vacuumi
side and its corresponding leg of the guage tube, so that if it be desired to
ascertain the number of inches of mercury, or the pounds per square inch of
pressure corresponding therewith, the plug or cock is turned one-sixth or
any other suitable portion of a revolution, and thus a passage between one
leg of the guage tube and the boiler, or other source of pressure, is opened,
whilst the other leg of the tube has a free communication with the atmo-
sphere. But if instead of pressure it is desired to ascertain the extent of
vacuum, then by turning the plug or cock in the opposite direction a.com-
munication is opened between the condenser or other exhausted vessel and
the other or vacuum leg of the guage tube, whilst a communication has at
the same time been opened between the pressure leg of the guage tube and
the atmosphere; thus the same instrument can be used almost instantaneously
for indicating successively either pressure or vacuum.