34 A FEDERAL REPORTER. c
sel is that it substitutes "an artiucial line" in place of a “branch cir·
cuit" or compensating circuit. lt is entirely clear that these terms
are used synonymous1y in the electrical art. The compensating cir-
cuit is commonly termed the artificial line. The specidcation states
that the branch circuit "is technically called the artificial line in order
to distinguish it from the main line." There is no merit in the crit-
icism.
It thus appears that the claim of the second reissue now in con-
troversy is not only no broader than claim 2 of the hrst reissue, but
it is specifically narrower in terms, although not so in effect when
` the specific elements required by construction to be incorporated were
read into that claim; and it also appears that the second claim of the
first reissue was no broader than was warranted by the invention. `
The claim in controversy is good, notwithstanding other claims of
‘ the reissue expand the claim of the original patent, or any claims
which the patentee might have lawfully made. As to this claim the
second reissue is valid if it is invalid as to the other claims. Gage
v. Herring, 107 U. S. 640; S. C. 2 Sup. Ct. Rep. 819. It protects
the complainant if the first reissue was lawful, and so much of the
invention as was not claimed in the original was not abandoned to the
public when that reissue was obtained. There has been no abandon-
ment since the first reissue was granted.
The case, then, hinges upon the validity of that reissue. Was it a
lawful exercise of authority on the part of the commissioner? Was
the patentee entitled to reclaim so much of his invention as he had
not claimed in the original? The test is found in the rule enunciated, '
among other cases, in Maha v. Harwood, 112 U. S. 354; S. G. 5 Sup.
Gt. Rep. 174. That decision covers two propositions applicable here. ~~
The first is that a patent cannot be lawfully reissued for the mere pur-
pose of enlarging the claim, unless there has been a clear mistake, in-
advertently committed in the wording ofthe claim, and the application
for reissue is made within a reasonably short time. The second is that
the question whether there has been such an inadvertent mistake
is, in general, a matter of fact for the commissioner to decide; but
, whether the application is made in reasonable time is matter of law
which the court may determine by comparing the reissued patents
with the original, and, if necessary, with the records in the patent-oh
lice when presented by the record. It was further decided in that case
that no invariable rule can be laid down as to what is a reasonable
time within which the patentee must seek for the correction of a claim
which he considers too narrow; that it is for the court to judge
in each case, and it will exercise proper liberality towards the pat-
entee; but as the law charges him with notice of what his patent
" contains, he will be held to reasonable diligence. In Coon v. Wilson,
113 U. S. 268, S. C. 5 Sup. Ct. Rep. 537, the reissue was applied for
only a little over three months after the date of the original patent, but
it was held to be invalid, because apparently made to enlarge the scope