Ives v. Hamilton - 92 U.S. 426 (1875)
U.S. Supreme Court
Ives v. Hamilton, 92 U.S. 426 (1875)
Ives v. Hamilton
92 U.S. 426
1. Where an improvement in saw mills, for which letters patent were issued consists of the combination of the saw with a pair of curved guides at the upper end of the saw and a lever, connecting rod or pitman, straight guides, pivoted cross-head, and slides or blocks and crank-pin, or their equivalents, at the opposite end, whereby the toothed edge of the saw is caused to move unequally forward and backward at its two ends while cutting. The claim is,
"giving to the saw in its downward movement a rocking or rolling motion by means of the combination of the cross-head working in the curved guides at the upper end of the saw, the lower end of which is attached to a cross-head, working in straight guides and pivoted to the pitman below the saw, with the crank-pin substantially as described,"
the use by another party of guides consisting of two straight lines representing two consecutive cords of the curve of the guides of the patentee, and arranged in other respects in the same manner as this curve, is clearly the employment of a mechanical equivalent, and is an infringement of the patent.
2. It is not a change in principle to pivot the lower end of the saw to the pitman below the cross-head, and, by a reverse motion of the crank or driving wheel, produce the same motion of the saw as when the pitman is pivoted above the cross-head.
3. The description in a patent for an improvement is sufficient if a practical mechanic, acquainted with the construction of the old machine in which
improvement is made, can, with the patent and diagram before him, adopt such improvement.
4. The essence of the improvement does not consist in the precise position in which any part is placed, but in a combination of mechanical means for producing a certain result.
The facts are stated in the opinion of the Court