# Du Bois v. Kirk

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United States Supreme Court
158 U.S. 58
Du Bois v. Kirk
This was a bill in equity for the infringement of letters patent No. 268,411, issued December 5, 1882, to Arthur Kirk, for a new and useful improvement in movable dams.
As stated in his specification, the invention 'relates to improvements in the construction of movable dams and locks, whereby they are stronger, safer, more durable, and more easily operated than those heretofore in use.' The specification sets forth an improvement in the style of dam known as the 'bear-trap dam,' in several different particulars, the fifth one of which consisted of 'an open sluice, waterway, or tail race, so arranged relatively to the dam that the water which is not required to support the leaves will escape, and so relieve the dam of all unnecessary pressure.'
The following drawings exhii t the device:
In relation to this portion of the patent the patentee states: 'In the end wall of the dam I make an open sluice, waterway, or tail race, 38, Fig. 2, at such height as will permit all water which is not required to sustain the gates to escape from under them. When the gates are down, as in the position shown in Fig. 1, the water is admitted by the wickets under them. This raises and floats them up until they reach the position shown by Fig. 2. By that time the water, having reached the sluice, 38, which passes through the wall around the end of the gate, will flow freely through, sustaining the gates at that level.
'A modified construction of the sluice, 38, is shown by Fig. 4, where the outlet, 39, in the wall is below the level of the water, the latter passing through the outlet, 39, into a forebay or well, 40, and thence over the bridge, 41. If desired, the discharge opening may be controlled by a valve operated by a float.
'It is apparent that the form, place, and details of construction of the sluice for relieving the gates from excessive pressure below can be varied by the skilled constructor; but in all cases an open channel will be necessary when the water has reached a certain height or pressure under the gates.'
The sixth claim, the only one alleged to be infringed, is as follows:
'(6) A bear-trap dam, having a relieving or open sluice extending from under the gates, so as to relieve them from unnecessary pressure, substantially as and for the purposes described.'
Three grounds of defense were set up and insisted upon by the defendant: First, that the alleged invention was not useful; second, that the device was in use by the defendant before the date of the alleged invention by the patentee; and, third, that the defendant had not infringed.
Upon a hearing upon pleadings and proofs the circuit court found in favor of the plaintiff upon all these issues (33 Fed. 252), and subsequently entered a final decree in his favor for an injunction, with nominal damages (46 Fed. 486). The defendant thereupon appealed to this court.
Mr. Justice Field dissenting.
G. A. Jenks, for appellant.
W. Bakewell and Thos.
W. Bakewell, for appellee.
Mr. Justice BROWN, after stating the facts in the foregoing language, delivered the opinion of the court.

## Notes

This work is in the public domain in the United States because it is a work of the United States federal government (see 17 U.S.C. 105).
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