Year: 1886

page_text: I, JOHN JOSEPH GHEGAN, of Newark, New Jersey, United States of America,
Electrician, do hereby declare the nature of this invention, and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
My invention relates to indicators or alarms for low water in tanks such as
reservoirs, boilers and similar containing vessels. The object is to provide a
device operating entirely by means located without the vessel containing the
water and yet being of such a nature as to be independent of jars, vibrations or
shocks communicated to the vessel.
It consists in the application of a piece of selenium to liquid level indicators or
alarms so that when the water becomes low, rays of light will fall upon the
selenium which by electrical means causes a signal to be given.
In order to illustrate the practical manner of carrying out the invention and to
enable others to construct and use the same, drawings are hereunto annexed
and described, in which similar characters of reference represent corresponding
elements.
The figure of the drawings is shown partly in cross section, and with some of
the parts broken away.
The liquid level indicator consists of the combination of a source of light such
for instance as a lamp A; a shield or screen B in whose opening is a condensing
lens C; a containing tube D of glass which may be considered as having liquid or
pipe connections E with a boiler or tank F; a float G made of opaque material
such as colored glass, sheet metal or of cork, or piece of wood, said float being
within the tube, and a piece of selenium H upon the opposite side of the tube
from the lamp and in the same horizontal line with the flame of the lamp; the
Belenium being in an electric circuit of constant and preadjusted resistance and
including an electric bell.
A funnel or ray collector I, is provided opposite the lens C.
In the normal condition, the water J in the tube is of such depth that the float
cuts off the rays K of light from falling upon the selenium, so that the circuit
remains practically of uniform resistance. But when the water sinks, the float
also sinks and the rays fall upon the selenium diminishing the resistance so much
•

page_text: that the current in the circuit becomes strong enough to ring the bell, or to
operate any similar translating device.
The invention is not limited to the precise construction herein before described
and shown as it is evident that many modifications may be made therein without
departing from the spirit of the invention.
In the place of selenium may be placed a substance whose electrical resistance is
influenced by heat, as heat rays always accompany light rays. The resistance of
carbon and metals thus varies but only slightly, while as stated in Sprague's
"Electricity, its sources and applications" page 10, the resistance of a piece of
selenium varied through 400 megohms in being taken from a dark room into a gas
lighted room.
Having now stated the object of the said invention; having described its
practical realization by reference to the accompanying drawing; having parti-
cularly ascertained the manner in which the same operates to accomplish the said
object; I declare that what I claim is ;-
First. The combination of a selenium cell with a translucent liquid containing
vessel, and a source of light substantially as described.
Second. In an automatic liquid level indicator, the combination of a source of
light; a liquid translucent containing vessel; an opaque float therein; and a piece
of selenium forming part of an electric circuit containing a translating device such
as an electric signal; said float being normally between said source of light and
said selenium.
Third. In an automatic liquid level indicator, the combination of a source of
light; a condensing lensa liquid translucent containing vessel; an opaque float
in said vessel; a piece of selenium; and an electric circuit including a translating
device such as an electric signal; said source of light, lens, float, and selenium
lying normally in an approximately straight line.
Fourth. In a liquid level indicator, the combination of a lamp; a double convex
lens attached thereto; a liquid containing vessel; a funnel shaped mouth fixed
upon the side of said vessel; an opaque float of glass in said vessel; a piece of
selenium; and an electric circuit containing an electric bell; said lamp, lens,
'funnel, float and selenium being normally in an approximately straight line, as
and for the purposes described.
Dated the 20th day of November 1986