Year: 1892

page_text: Date of Application, 12th Sept., 1892-Accepted, 22nd Apr., 1893
material in place.
In these views let the reference numeral 1 designate a block of insulating material
through the centre of which passes a metal stem 2 provided with an insulating
button or knob 3.
At the bottom of plate 1 stem 2 is passed through a stationary metal arm 4
and secured in place by a nut 5 and is designed to be rotated by taking hold of
button 3.
To a screw 6 passing through arm 4 is attached one of the circuit wires 7.
Secured to stem 2 and adapted to engage the upper surface of block 1 is an
arm 8. The outer extremity of this arm engages small metal pieces or plates 9
secured to block 1 by screws 10 passing through the block, the heads being located
underneath.
Plates 9 are distinct and separate from one another and form either a circle or
an arc of a circle around stem 2.
Supported upon plate 1 and extending around the stem 2 on the outside of
plates 9 and forming either a circle or arc thereof as may be desired, is a section 12
of carbon or other suitable resistance material preferably circular in cross section.
The carbon 12 is connected with screws 10 and therefore with plates 9 by
wires 13 extending from the head of the screws up through the block 1 to clamps 14
surrounding the carbon and secured at the top by screws 25.
It will thus be seen that these clamps may be adjusted to correspond with the
condition of the carbon with reference to the change produced therein by a
difference in temperature producing expansion and contraction. Each wire 13 is
distinct and separate from every other wire 13.
As before stated one circuit wire 7 leads to or is connected with arm 4 secured
to stem 2. The other circuit wire 15 is connected with the head of a screw 10
located at one extremity of the arc in which the screws are arranged.
Now it will be seen that the circuit in which the lanp to be controlled lies is
completed from wire 7 through arm 4, stem 2, arm 8, plate 9 and screw 10 to the
other wire 15, provided the lamp is turned clear on and the current does not
have to pass through any portion of the carbon 12, which is the case when the
outer extremity of arm 4 is directly above the screw 10 with which wire 15 is
electrically connected.

page_text: When, however, it is desired to turn down the lamp or regulate the brilliancy,
stem 2 is turned to the left over plates 9 or away from the screw 10 with which
wire 15 is connected, thus compelling the current to travel through a greater or
less resistance according to the strength of light required. It will thus be seen
that the light may be nicely regulated and controlled by the use of my improved
device.
The last plate 9 to the left or the one farthest from the one with which wire 15
is connected, should not be connected with the carbon. Hence when ȧrm 8 reaches
this plate the light is extinguished.
The device is provided with two plates 16 and 17, one secured to the base
of plate 1 and the other connected with stem 2, and both connected with wire
cloth 18, thus forming a shield for the parts and at the same time permitting free
circulation of the air for the purpose of keeping the mechanism at a sufficiently
low temperature.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
FirstA rheostat consisting of an insulating block 1 provided with a number
of metal plates 9 arranged in a segment, each being separately secured to the
block, a resistance carbon supported upon plate 1 and electrically connected with
each plate 9 by a separate wire, a rotating stem passing through block 1 and
provided with a metal arm adapted to engage plates 9, and a circuit the wires of
which are electrically connected respectively with the post and the plate 9 at one
extremity of the arc formed by the series of plates, substantially as and for the
purpose set forth.
Second A rheostat consisting of an insulating block 1 provided with a series
of plates 9 insulated from each other, metal screws 10 passing up through the
block into said plates, a carbon resistance supported upon block 1 and provided
with clamps 14 surrounding the carbon and secured by adjusting screws 25, a wire
connecting each screw 10 with a screw 25, a rotating metal stem 2 secured to
plate 1 and provided with a metal arm adapted to engage plates 9, and a circuit
the wires of which are electrically connected respectively with stem 2 and the
plate 9 at one extremity of the series of plates, substantially as and for the purpose
set forth.
Third: A rheostat consisting of a block 1 provided with a series of metal
plates 9 arranged in a segment and separated from one another, metal screws 10
passing up through block 1 and into these plates, a carbon resistance supported
upon plate and surrounded by adjustable clamps, a separate wire connecting
each clamp with a screw 10, one plate 9 being disconnected from the carbon and
lying without the circuit, a rotating metal stem provided with a metal arm
adapted to engage plates 9 and a circuit the wires of which are electrically con-
nected respectively with the stem and with a plate 9 at one extremity of the series,
substantially as and for the purpose set forth.
Fourth A rheostat consisting of an insulating block 1 provided with a series
of metal plates 9 arranged thereon in the form of a segment and insulated from
one another, metal screws 10 passing up through block into said plates, a carbon
resistance provided with adjustable clamps, wires connecting said clamps with
screws 10, a rotating metal stem 2 passing through block and provided with a
metal arm adapted to engage plates 9, a circuit the wires of which are electrically
connected respectively with stem 2 and the plate 9 at one extremity of the series,
and a casing enclosing the mechanism and provided with foraminated sides, substan-
tially as and for the purpose set forth.
Datel this 21st day of August A.D. 1892.
HENRY WALLACE LAWRENCE.