Improvements in Electric Switches.
Year: 1898

page_text: Date of Application, 13th Dec., 1898-Accepted, 18th Feb., 1899
DI PUITICALIUN.
Improvements in Electric Switches.
We, WILLIAM JOHN FERGUSON, Engineer, and WILLIAM GILPIN HARRISON
STUMP, Manager, both of the Equitable Building in the City of Baltimore, State
of Maryland, United States of America, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:―
This invention relates to a switch for making and breaking an electric current.
The object of the invention is to produce a switch that shall combine the
terminals of an electric circuit; and mercury which shall be mechanically shifted
from one position to another, so that the mercury by contacting with said ter-
minals will complete the circuit.
The invention is illustrated in the accompanying drawings in which:-
Figure 1 is a front view of the switch.
Figure 2 is a section view of same on line 2-2 of Figure 3,--the front plate
being removed and showing the interior of mercury chamber.
Figure 3 is a diametrical section of the switch.
Figure 4 is a cross-section on the line 4-4 in Figure 2 and shows the terminals.
The case, A, may be of any desired shape but must have an interior circular
or part circular chamber, b. The walls of this chamber must be made of or lined
with insulating material. This chamber b, is preferable narrow and is occupied
by a non-conducting segment-plate, C, and mercury, d, as a conductor which
together fill it. The segment-plate, C, of non-conducting material is half-circular
and snugly fits so as to turn in the chamber, d. This plate has a half-collar, e,
and a central hole into which the shank, f¹, of the thumb or key, f, fits. This
key-shank turns loosely in a hole in the front-plate; g, of the case. An index
or pointer, h, is attached to the key and projects along the front plate at the same
side where the segment-plate, C, is attached; on the front plate at one side may
be the word " on,
indicating that when the index, h, points here the circuit
is complete and the current is on. At the opposite side the plate may have the
word off," when the index points to this latter word it will indicate that the
circuit is broken and the current is off.
"
The innermost or back wall, I, is made of insulating material, and is secured
in position by screws, j, or otherwise; the narrow chamber, b, is between the front
plate, g, and the back wall, I. Two binding posts, k, k, have their ends entered
through the back wall and these ends are exposed in the chamber and constitute
the terminals, 7, of an electric circuit.
When the mercury, d, in the chamber is in one position it will cover both
terminals, 1, and thereby will complete the electric-circuit through the two
binding posts, k, and the wires attached to them; but when the key, f, is turned
and the non-conducting plate, C, makes a half revolution within the chamber
it will take position across the exposed ends of the terminals, l, and the mercury
will be forced from the terminals to the opposite side of the chamber, thus
breaking the circuit.

page_text: By this combination comprising the terminals of an electric circuit, mercury
to contact with the terminals and complete the circuit, and a rotary non-con-
ducting plate which shifts the mercury from one position to another, an efficient
device is provided which will make and break the electric circuit.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. An electric switch having in combination a case with a stationary circular
chamber; the terminals of an electric-circuit exposed in said chamber; a segment-
shaped non-conducting plate in the chamber pivoted so as to turn therein like
a rotary key; and mercury in said stationary chamber which shall be shifted
by turning said segment-shaped plate.
2. An electric switch having in combination a case with an interior chamber;
the terminals of an electric-circuit exposed in said chamber; mercury in said
chamber which in one position covers the said terminals and completes the circuit;
and a non-conducting plate in the chamber and pivoted so as to shift the mercury
and cause it to take either the make or the break position..
3. An electric switch having in combination a case with an interior chamber;
the terminals of an electric-circuit exposed in said chamber; mercury in said
chamber which in one position covers the said terminals and completes the circuit;
a non-conducting plate in the chamber and pivoted so as to shift the mercury
and cause it to take either the make or break position, and a thumb-piece on the
outside of the case and attached to the pivoted non-conducting plate.
Dated this 21st day of November 1898.
WILLIAM JOHN FERGUSON.
WILLIAM GILPIN HARRISON STUMP.