32 FEDERAL REPORTER.
relay at each station upon a duplex telegraph line. Of course a du-
plex telegraph implies a line with a receiving and transmitting sta-
tion at each end of it. The drawings of the patent show only one
end of such a line, and the specification of the original describes the
apparatus in detail, including a condenser, a battery, and a branch
circuit or compensating line with a rheostat in it at that end of the
line shown in the drawing. It may fairly be assumed that the claim
was expressed in the terms used in order to exclude any implication
that the invention consisted in employing the condenser at one end
of the line or at one station only. The real invention of Stearns did
not require his condenser to be employed in combination with the
rest of the apparatus at both ends of the line. If a condenser were
used with the apparatus at one station only, the static effect of in-
duction would be neutralized at that end of the line only. The com-
, bination would be operative and advantageous to this extent; but it
would be less so than if it were used in the apparatus at each station.
If condensers were placed at both stations in the required combina-
tion, signals at both could be more rapidly and perfectly received.
It admits of fair argument whether it would not have been a fair
construction of the claim of the original to interpret it as meaning
the combination of a condenser with the two relays of the duplex
system. It would have been the duty of a. court to construe the
claim in such a way as to protect the real invention unless the lan-
guage of the specification and theclaim would preclude such a con-
-struction. The case does not turn solely on this point, however,
because within 11 months from the granting of the original patent
it was surrendered, and a reissue granted, which contained this
claim:
"C1aim 2. In an apparatus for double transmission, the combination of a
condenser with a branch or compensating circuit, whereby the effect of static
induction upon the receiving relay or instrument is countcracted, substan-
tially as and for the purpose herein specified."
The specification was amended by inserting as follows:
"As the apparatus at each terminal station is similar, the diagram repre-
·sents the apparatus at one station only."
In this claim every unnecessary element of the combination is elim-
inated. It covers the invention in the broadest form in which it can
be stated. Limited, as its terms must be, by the descriptive matter
of the specification, and read in view of the prior state of the art,
the claim was not too broad. It does not require a condenser at each
station as a constituent. In other respects, as is argued for the de-
fendant, the claim is narrower in terms than that in the original, be-
cause it restricts the combination to one in which the condenser is
employed with "a branch or compensating circuit." If this claim
included as one of its constituents, by fair interpretation, "a con-
denser having its terminals, respectively, connected with said artifi-