THOMSON-HOUSTON ELECTRIC C0. *11. WESTERN ELECTRIC C0. 77
ments when all three segments and their corresponding armature coils a1·e
simultaneously in direct contact with the collecting brushes correspond to
the times when either of the collecting brushes, C, C’, is over a slot between
any two segments. At this moment a transfer of the current takes place
from the coil and segment, leaving the commutator brush to the succeed-
ing coil and segment coming into contact therewith, which transfer is re-
peated at every slot ln the commutator. Thi  transfer occupies an appreci-
able time, and the current produced is due to the resultant action between
the coils in their maximum position operating in conjunction with coils that
have either passed, or have not attained, that position, when in circuit with
the collectors, C, C’.
"We have hereinbefore described our method of regulating the strength
of the current traversing the circuit by a movement of the commutator col-
lecting brushes, so that whatever be the number of lamps in the circuit, up
to the maximum, the normal current strength may be obtained; but as,
in practice, the lamps are generally at a distance from the dynamo-electric
machine furnishing the current, and as the switching out of circuit of one
or more of the lamps would necessitate an adjustment of the commuta-
tor-brushes, as before described, we prefer to effect said adjustment auto-
matically, and without the introduction of resistance coils, and maintain,
notwithstanding changes in the number of lamps used upon the circuit, a
practically uniform current strength without requiring the attendance of
the operator. We find in practice, moreover, that we obtain with this auto-
matic regulation of the current strength an independence of speed varia-
tions in the machine, it being only necessary to so adjust the speed of
running that when the speed is at its lowest the machine shall yet be sutli-
cient in power to maintain the number of lights placed in its circuit. We
are therefore able to operate successfully under conditions of motive-power
variations that have hitherto been recognized as fatal to steadiness of light
"obtained. ’
"In United States patent N0. 223,659 (January 20, 1880) before referred to,
we have described a means of automatically adjusting the commutator col-
lectors of dynamo-electric machines, which method is adaptable to the pres-
ent case of current regulation. When a single pair of commutator col-
lectors, C, C’, a1·e employed with an inclined or angularly slotted commu-
tator, as hereinbefore mentioned, the current of the machine is caused to
traverse an electro-magnet, the variations in the power of which current
and magnet either directly or indirectly serve to effect the adjustment of
the commutator collecto1·s, with or without centrifugal regulation, in a simi-
lar way to that shown and described in patent No. 223,659, before referred
to. The regulation of the current strength is readily obtained by causing
the main current of the machine, or a shunted portion thereof, to traverse
an electro-magnetic controlling device, operating to throw into or out of
action an electro-magnet or equivalent motor device, which, in turn, im-
parts motion to the commutator collecting brushes. As in our former in-
vention, already referred to, they motor device used may be adapted to move
by the current, or by the motive power, or by suitable clockwork, or other
mechanism adapted to be thrown in or out of action by an electro—magnet,
and constitutes, as before, a minor feature of our present system. Our
present method of operating, therefore, so far as it relates to automatic
regulation, is based upon the same principles of operation as our previous
invention; and it consists in an improved construction and mode of use of
the apparatus employed in patent No. 223,659.
i "In Fig. 2 the direct current of the machine is conveyed through the coils
-of the electro-magnet, D, placed in the circuit of the machine at any con-
venient point. `Its armature, E, is suitably supported so as to be movable
to and from the electro—magnet, as by the lever, F, and held away from the
magnet by an adjustable spring, Z. Two contact pieces, p, q, are pro-
vided, adapted to be closed or opened by movements of the lever, F, due
to variations in the power of the electro-magnet, D, following changes in
the current. V The contact pieces, p, q, serve as a shunt of small resistance
or short circuit around an electro-magnetic coil, G, provided with a mova-
ble core, H, suitably supported in the axis of the coil. Thecore, H, ls