WESTERN UNION TEL. oo. ·v. BALTIMORE & 0. TEL. oo. ~31
original inventor of a very valuable improvement in duplex telegraphy,
which obviated a serious practical difficulty in duplex transmission.
over long lines, caused by the interference of the return charge aris-
ing from static induction with the operation of the receiving instru-
ment at the transmitting end. He did this by a new combination of
old instrumentalities. He added to the existing duplex telegraph a .
condenser, so placed that it would receive a charge from the battery
equivalent to the charge which the line at the same time received, l
and would discharge thatcharge around one coil of the relay at the
same time the line discharged its charge around the other coil, so that
the armature between the two coils would not be moved by the dis-
charge from the line. As is stated in the affidavit of one of the de-
fendants’ experts, "no one before Stearns had endeavored to obviate
the effects of the return current due to the static induction upon the
receiving instrument in duplex telegraphy with the exception of Var-
ley; and the device used by Varley was not a condenser, nor was it
in any sense the known equivalent of a condenser. "
The invention thus made by Stearns was fully and clearly described
in the specification of the original patent. The claim of that patent
upon one construction may be deemed to have been narrower than
the real invention. This, however, would affect only the question of
infringement. A new and valuable invention was described and
claimed. ’
It is not necessary, in considering the hrst objection to the validity
of the patent, to inquire into the prior state of the art. The defend-
ants’ expert says: "The claim does not appear to cover any more
than the patentee had a right to claim in view of the state of the art
at that date. " This concession renders such an inquiry unnecessary,
but the concession is abundantly fortified by the facts as they appear
upon this motion.
The real question in the case would seem to be whether the reissue,
so far as it affects the claim infringed, is void. The claim involved
is as follows:
"The combination, in a duplex telegraph, substantially as hereinbefore set
forth, of a battery, a main line, and artificial or compensating line, a rheo- ·
stat in said artificial line, and a condenser having its terminals, respectively,
connected with said artificial lines and the earth."
The claim of the original patent reads as follows: ,
"In tele rraph apparatus for double transmission, the combination, with the
relay at each station, of a condenser, for the purpose of neutralizing the effect
of the return current due to the static induction of the line, as set forth."
If the case turned solely upon the question whether the claim of
the reissue is broader than that of _the original, a sufficient doubt
would be suggested to require a motion for an injunction to be de-·
nied, because a fair doubt is sufiicient to defeat such a motion.
The claim of the original may fairly be construed as limited to a
combination in which a condenser is employed in connection with the
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