Opinion of the Court.

from the generator shall act with additional force after it has lifted the valve from its seat at the ground joint, and so, by overcoming the rapidly increasing resistance of the spring or scales, insure the lifting of the valve still higher, thus affording so certain and free a passage for the steam to escape as effectually to prevent the bursting of the boiler or generator, even when the steam is shut off and the damper left open.

"To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation. To the head of the common safety-valve, indicated by all that portion of Fig. 2 lying within the second circle from the common centre, I add what is indicated by all that portion lying outside of the said circle, in about the proportion shown in the figure. A transverse vertical section of this added por

Opinion of the Court.

tion is indicated, in Fig. 4, by those portions of the figure lying outside of the dotted lines p.p, p p, while all that portion lying within the dotted lines pp, p p, indicates a transverse vertical section of the common safety-valve alone. This increased area may be made by adding to a safety-valve already in use, or by casting the whole entire. I terminate this addition to the head of the valve with a circular or annular flange or lip, c c, which projects beyond the valve-seat E E, Fig. 3, and extends slightly below its outer edge, fitting loosely around it, and forming the circular or annular chamber D D, whose transverse section, shown in the figure, may be of any desirable form or size. This flange or lip c c, fitting loosely around the valve-seat E E, is separated from it by about of an inch, for an ordinary spring or balance. For a strong spring or balance this space should be diminished, and for a weak spring or balance it should be increased, to regulate the escape of the steam, as required. Instead of having the flange or lip c c project beyond and extend below and around the outer edge of the valve-seat, as shown in Fig. 3, a similar result may be obtained by having the valve-seat itself project beyond the outer edge of the valvehead, and terminating it with a circular or annular flange or lip, extending slightly above, and fitting loosely around, the outer edge of the flange or lip c c of the valve-head; but I consider the construction shown in Fig. 3 preferable. With my improved safety-valve, constructed as now described, and attached to the generator in the usual way, the steam, escaping in the direction indicated by the arrows in Fig. 3, first lifts the valve from its seat at the ground joint FF, and then, passing into the annular chamber D D, acts against the increased surface of the valve-head, and by this means, together with its reaction produced by being thrown downwards upon the valveseat E E, it overcomes the rapidly increasing resistance of the spring or balance, lifts the valve still higher, and escapes freely into the open air, until the pressure in the generator is reduced to the degree desired, when the valve will be immediately closed by the tension of the spring or balance. The escape of the steam by means of this safety-valve is so certain and free, that the pressure of the steam in the generator or boiler will

VOL. CXII-11

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not increase beyond the point or degree at which the valve is set to blow off."

The claim of the patent is this: "What I claim as my improvement, and desire to secure by letters patent, is a safety. valve with the circular or annular flange or lip c'c, constructed in the manner, or substantially in the manner, shown, so as to operate as and for the purpose herein described."

On the 2d of June, 1879, the same plaintiff brought a suit in equity, in the same court, against the same defendant, for the infringement of letters patent No. 85,963, granted to the same George W. Richardson, January 19, 1869, for an improvement in safety-valves for steam boilers or generators. So much of the specification of the patent as is involved in this suit is as follows:

"Be it known, that I, George William Richardson, of Troy, in the State of New York, have invented certain new and useful improvements in safety-valves for steam boilers or generators; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings making part of this specification, in which Figure 1 is a vertical section of the safety-valve and its connections, taken in the plane of the axis of the valve-stem; Fig. 2, a horizontal section taken in the plane of the line A a of Fig. 1, and Fig. 3 another horizontal section at the line В b of Fig. 1. Fig. 4 is a vertical section taken in the plane of the axis of the valve, representing a modification of my said invention; and Fig. 5, a horizontal section thereof, taken in the plane of the line Cc of Fig. 4. My said invention relates to improvements in the invention described in letters patent granted to me, and bearing date the 25th day of September, 1866, which said patented invention relates to a means for providing a more free escape for the steam than could be obtained by safetyvalves as constructed prior thereto, and to insure the keeping of the valve open until the pressure of the steam in the boiler or generator falls below the pressure which was required to open it, the said means so patented consisting in forming the valve with a surface outside of the ground joint, for the escaping steam to act against, the said surface being surrounded by

escape for the steam when the valve is opened, but which, although of greater diameter than the valve-seat, by reason of

B

Opinion of the Court.

a projecting or overlapping lip, rim, or flange, leaving a narrow

Fig.3.B.b.

Fig.4.

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the said lap, presents a less area of opening for the escape of steam than is produced at the valve-seat, so that the steam which escapes through the area between the valve shall exert pressure against the said surrounding surface, and thereby not only open the valve completely, but hold it up until the pressure of the steam in the boiler falls below the pressure by which the valve was opened.

"One part of my present invention relates to a means for regulating or adjusting the area of the aperture for the escape of the steam after acting on the said surface outside of the valve-seat, so that the valve may be set to close at any desired pressure below the pressure which will open it; and this part of my invention consists in making the aperture or apertures for the escape of the steam, after it has acted on the said surface outside of the valve-seat, adjustable.

"I will first describe the preferred mode of application of my said invention, as represented in Figs. 1, 2, and 3 of the accompanying drawings. In the said figures, a represents the valveseat, which is to be attached to a steam boiler or generator in the usual or any other suitable manner, and which is formed, in the usual manner, with a bevelled seat from the valve b, fitted thereto by what is well known as a 'ground joint.'

"It is desirable, that, so soon as the pressure of the steam in the boiler or generator reaches the pressure at which it should be relieved, the safety-valve should open wide for the free escape of steam, and that the valve should remain open until the pressure in the boiler is reduced below the pressure by which the valve was opened, and that it should be so organized that the engineer may be able to adjust it so that it will close at any desired number of pounds pressure below the pressure at which it was opened. To accomplish these results was the main object of my said invention.

"To the upper surface of the valve I secure a cap-plate or annulus, m, formed with a downward-projecting flange, n, at its outer periphery, leaving an annular space, o, all around between the outer periphery of the valve and the inner periphery of the flange n of the said cap. And the upper surface of the valve-seat a is extended all around, a little beyond the outer