U.S. Supreme Court
Miller v. Eagle Mfg. Co., 151 U.S. 186 (1894)
Miller v. Eagle Manufacturing Company
Argued December 11-12, 1893
Decided January 8, 1894
151 U.S. 186
No patent can issue for an invention actually covered by a former patent, especially to the same patentee, although the terms of the claims may differ.
The second patent, in such case, although containing a claim broader and more generical in its character than the specific claims contained in the prior patent, is also void.
But where the second patent covers matter described in the prior patent essentially distinct and separable, and distinct from the invention covered thereby and claims made thereunder, its validity may be sustained.
A single invention may include both the machine and the manufacture it creates, and in such case, if the inventions are separable, the inventor may be entitled to a monopoly of each.
A second patent may be granted to an inventor for an improvement on the invention protected by the first, but this can be done only when the new invention is distinct from and independent of the former one.
It is only when an invention is broad and primary in its character and the mechanical functions performed by the machine are as a whole entirely new that courts are disposed to make the range of equivalents correspondingly broad.
The invention claimed and protected by the letters patent issued June 7, 1881, to Edgar A. Wright for new and useful improvements in wheeled cultivators was anticipated by the claim in letters patent No. 222,767, granted to him December 16, 1879, for improvements in wheeled cultivators.
The first claim in the said letters patent of June 7, 1881, was anticipated by letters patent No.190,816, issued May 15, 1877, to W. P. Brown for an improved coupling for cultivators. chanroblesvirtualawlibrary
The said letters patent of December 16, 1879, in view of the state of the art at that time, are to be limited and restricted, if they have any validity, to the specific spring therein described, and as thus restricted, they are not infringed by the sale of cultivators manufactured by P. P. Mast & Co. in accordance with various letters patent owned by them.
In equity for the infringement of letters patent. The case is stated in the opinion.