MR. JUSTICE SWAYNE delivered the opinion of the court. This is a case in equity. The bill is founded upon two patents. One of them is reissue No. 3570. It bears date on the 27th of July, 1869. The original of this reissue-No. 81,010bore date on the 11th of August, 1868. The other patent is dated June 21, 1870. It is numbered 104,585, and was issued to the appellees as the assignees of Hardy and Wood, the alleged inventors.

The bill was dismissed, as to this latter patent, at the hearing, and no appeal was taken. It may, therefore, be laid out of view, and will not be again adverted to. The other original patent and the reissue are for improvements in cases for rotary blowers.

The bill charges infringement, and prays for an injunction and a decree for profits and damages. The answer denies the novelty of the alleged invention; denies that the reissue is for the same thing as the original patent; denies that the complainants were joint inventors, if inventors at all; and denies infringement.

Such were the issues made by the appellant in the court

below. That court found all of them in favor of the appellees, and decreed accordingly.

Here the same points have been insisted upon.

In relation to all of them, except the one last mentioned, we deem it sufficient to say that we concur with the court below. We think the evidence leaves no room for a reasonable doubt as to either of them. The questions are questions of fact. No legal proposition is involved. To analyze the testimony in order to vindicate our conclusions would serve no useful purpose. Our further remarks will be confined to the subject of infringement. That is the hinge of the controversy between the parties.

It is difficult to convey clear ideas of complex machinery by any description that can be given. Drawings are more effectual, and models are still more so. If the model be full and accurate, it is, indeed, the thing itself in miniature.

The appellees, as the case is before us, confine their claims to improvements in the shell or case of blowers. The internal mechanism is in no wise in question. They say the objects of their invention were to avoid the necessity of boring out the interior concave surfaces of the case, and of facing off or planing the head-plates, and to render it practicable to cast the entire outside casing in one piece. They describe two modes of making the blower-heads true. One is to form them into planes at right angles to the shafts of the abutments, parallel with each other, equidistant from each other in all their parts, by giving to the inner surface of each plate a coating of plaster of Paris, hydraulic cement, or other material, having like plastic properties. This is suited to blowers of the smaller sizes. When this method is used, the plaster of Paris may be put on while in a plastic condition, by means of a sweep made to turn in the boxes of the blower-shafts, so that it will shape the linings of the ends as may be desired.

The second method is to use inside or secondary metal plates made in their outlines to conform to the interior of the case, and to face or plane them off so as to make them perfectly true. A space is left between these secondary plates and the ends of the case, which is filled with plaster of Paris of the proper consistency. After the plaster has set, the plates are secured

in their places in any suitable manner. In making the inner surface of the arcs of the case true, the usual way of the patentees is to work from the centre of the shaft-journals as fixed points.

They give the inner part of the concaves a coating of plaster of Paris, and work it into the proper shape and proportions while it is setting, by means of a sweep attached to a shaft turning in the journal-boxes of the blower, as in the case of the head-plates when plaster is applied to them. While the plaster or other similar material is becoming set, they slowly move the sweep, so as to give the coating exactly the required shape and thickness. Sometimes, instead of using the sweep, they use a cylinder of a diameter corresponding with the sweep or the circles to be described by the pistons. The cylinder is hung on a central shaft resting in the journal-boxes. The plaster is then poured into the intervening space between the cylinder and the case and the "metal guards,”— which are small projections on the inner surface of the case, intended to support the coating. When the plaster is set the cylinder is removed, and leaves the required arcs of a circle.

They do not cast very large blowers in a single piece. Those ordinarily used by blacksmiths and medium-sized foundry blowers are so cast.

If the case of a rotary blower be cast in one piece, it is necessary that the concave arcs of the case should be of such dimensions, and so placed on one side of the plane of the axis of the shafts, as to allow the removal of enough of the head-plates of the case to afford a sufficient opening for the introduction or removal of the abutments without interfering with any part of the case otherwise than to remove or replace the boxing which holds the shafts. By making the concave arcs a little more than a quarter of a circle, and placing them chiefly on one side of the plane of the shafts, the opening on the opposite side of the plane is correspondingly increased, allowing ample room for putting in and taking out the abutments, and also allowing the reduction of the end-plates on the open side of the plane, where they would otherwise interfere. If the concave arcs were materially increased and divided near equally on the

two sides of the plane of the shafts, the abutments of a case so made could not be taken out or replaced without taking the case apart, and the case would need to be made accordingly.

The claims are,

1. A rotary blower-case, the interior of which is made true by means of plaster of Paris, or its equivalent, applied as described.

2. Such a blower-case, the ends of which are made true by the application of plaster, or a like material, as described.

3. Such a blower-case, the concaves of which are made true by the use of such material, applied as described.

4. Such a blower-case, having the concave arcs in combination with the end-plates, so arranged as to admit of the abutments being introduced or removed without requiring the case to be taken apart, as described.

5. A rotary blower-case, the ends of which are made true by the use of secondary inside metal plates, as and for the purposes described.

6. The metal guards in the inside of the concaves, as described.

The specification sets forth in strong terms the great value of the invention claimed.

There is a marked difference between a fan blower and a rotary blower. They operate on different principles. The former makes from one hundred to three hundred revolutions per minute; the latter, from three thousand to six thousand in the same time. The appellees are the original inventors of the rotary blower. Such is their proof, and there is none to the contrary. Its value in the useful arts is evinced by its tested capabilities, and the ardor of this litigation. No patent of the appellees is in any wise involved in this controversy but the one we have analyzed.

The appellant has a patent also. It bears date on the 9th of August, 1870, and is No. 106,165. It covers both the shell or case and the inner machinery. The claims are for,—

"1. The blower-case A, made to support the abutting pistons, the circle or sweep of which in the surrounding case is lined with a cement of beeswax and resin or brimstone, retained