Du Bois v. Kirk

• Citation: 15 S.Ct. 729,39 L.Ed. 895,158 U.S. 58
• Decision Date: 22 April 1895
• Docket Number: No. 240,240
• Parties: DU BOIS v. KIRK
• Court: United States Supreme Court

158 U.S. 58

15 S.Ct. 729

39 L.Ed. 895

DU BOIS

v KIRK.

No. 240.

April 22, 1895.

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 pres- sure 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.

Bear-trap dams are used in small streams for the purpose of creating a reservoir of water, in which logs may be collected, and over which they may be floated down the river when the dam is opened. These dams are movable, and consist of two leaves of neavy timbers, bolted together, rising and falling between two vertical side walls of masonry or timber work. These leaves are hinged at their outer edges to timbers in the bed of the stream, and, when the dam is down, the upper leaf overlaps the other to a certain extent. Parallel with the stream, at one or both sides of the dam, is a sluice, termed a 'forbay,' at each end of which is a gate or wicket, for the admission of water at its upper end from the pond, and its discharge at its lower end into the tail race. When it is desired to raise the dam, and create a reservoir of water, the wicket at the upper end of the forebay is opened, and that at the lower end is closed. The effect of this is to admit the water into the forebay, from which it flows through openings provided for the purpose under the leaves of the dam, and, by hydrostatic pressure, raises them gradually up to their full height, when they assume somewhat the shape of the letter A. When it is desired to lower the dam, and create what is known as a chute for the passage of logs, the wicket at the upper end of the forebay is closed, and that at the lower end is opened, the effect of which is to exhaust the water from the forebay and from beneath the dam. As the water runs out, the leaves of the dam fall to a horizonatal position, and the water from the reservoir pours out through the chute thus formed. If, however, the volumeo f water be so great as to raise the water in the forebay above the height of the dam, the pressure underneath the leaves may become so great as to tear the lower leaf from under the upper one, and thus wreck the dam, and, perhaps, create a serious flood below it. It is said that an average difference of three feet between the level of the water in the forbay and the leval in the chamber under the dam would exert upon leaves, each of which is 450 square feet in area, an upward pressure of 97,200 pounds. To resist this hydrostatic pressure the common practice was to limit the upward motion of the lower leaf by stops, cleats, or chains, or have a man constantly on watch to relieve the pressure by opening or closing the wickets in the forebay, as required.

The object of the invention in question was to do this automatically, by opening an overflow underneath the apex of the leaves of the dam, so that, when they reached their full height, any further pressure upon them would be relieved by the surplus of water running out through this overflow or waste weir into the tail race. An alternative device is shown in Fig. 4, by which, instead of permitting the water to run off through a waste way, located near the apex of the dam, it is allowed to run over the lower end wall of the forebay, which for that purpose is made a few inches lower than the apex of the dam. Under the laws of hydrostatic action, lowering the water in the forebay also lowers it in the chamber beneath the dam to precisely the same level, this chamber being connected with the foreday at the bottom.

Waste ways were a common and wellknown method of relieving the pressure of water, but had, before the Kirk invention, been generally, if not universally, used to draw off the water from the pond above the dam, when it reached a certain height, and thereby the pressure upon the dam was relieved. Indeed, the dam itself becomes a waste way as soon as the water in the pond reaches a higher level than the apex of the dam, and flows over it. It would appear that at the time of the Kirk invention there was no recognized method of relieving the pressure of the water underneath the leaves of a bear-trap dam, and that the dam was prevented from being carried away only by cleats or chains to brace the structure, and enable it to resist the pressure from beneath.

The invention seems to have occurred to Kirk upon the occasion of a visit of a delegation of the Pittsburgh chamber of commerce, on Christmas Day of 1879, to a bear-trap dam erected by John Du Bois, an uncle of the defendant, who had recently patented an overlapping third leaf, designed to hold down the other leaves. This improvement, as stated by one of the witnesses, 'consisted in adding a third leaf, which was hinged to the downstream end of the up-stream leaf in such a way that when the dam was raised the downstream leaf was supported and held in place by a third leaf.' Kirk was not satisfied with this...