the boiler to heat more readily, a portion of the rear end vertical plate of said stove is removed, so as to uncover the upper portion of the rear-end vertical flues, and the front of the boiler is attached to the rear of said flues, in the manner shown and described in my reissued patent of July 24, 1866. Between the inner side of the boiler, B, and the rear end vertical flues, K, and L, L', a plate may be employed, indicated by dotted line, w, w. The object of this plate is as follows: It has been ascertained by experience that when during the use of the oven for baking purposes, a large quantity of cold water is suddenly poured into the reservoir, and there is nothing between the front of the boiler and gases of combustion passing through the rear end vertical flues, the heat of the said gases will be so much absorbed by the reservoir as to sensibly cool the oven and interfere with the process of baking. To obviate this I employ the thin plate, w, w, placed between the front of the reservoir and the said rear end vertical flues, and which, while it allows sufficient heat to pass through it to aid in heating the boiler, protects the front thereof from the direct impact of the gases of combustion, and preserves an equable heat in the oven. In case the said plate is dispensed with the inner side, J, of the said boiler will form a part of the lateral rear casing of the said rear end vertical flues, and will be heated by direct contact with the gases of combustion as they pass down and up the same. M is the fire-box, and N and R the top and bottom flues of said stove. The operation of my said invention is as follows: A fire being kindled in the fire-box, M, and the damper, Q, at the top of the oven being open, so as to allow of a direct draft, the gases of cumbustion from the said fire-box will pass down the middle vertical flue, K, through the exit-passage, F, and exit-flue, E, E', to the smoke-pipe I, heating the contents of the reservoir in its passage through the exit-flue, as aforesaid. By this mode of construction I am enabled to obviate what has been heretofore the greatest objection to reservoir-stoves of this class, namely, that the reservoirs would not heat with a direct draft. It will also be observed that, by this device of constructing the exit-passage below the top of the oven, I can at the same time, by a direct draft, heat the rear side of the oven and the reservoir, instead of wasting the heat by carrying it directly to the chimney. When the damper, Q, is closed, for the purpose of heating the oven, the gases of combustion will pass down the side vertical flues, L, L', and under the bottom of the oven, returning through a central horizontal flue to the central vertical flue, K, from which they pass through the exit-flue, E, E', as aforesaid. I am aware that cooking-stoves have been in use in which the reservoir has been incased or inclosed on all sides except the top by a kind of expanded flue, through which the gases of combustion are made to pass. The advantages of my plan over this device are twofold: First, it is much more economical, requiring far less material and labor to construct it; and, second, by confining the heat and gases of combustion to a small space at the bottom and rear of the reservoir, the contents thereof will be much more effectually heated than where the products of combustion are admitted to an extensive flue-space and permitted to rise and expend their heat at or near the top of the reservoir."

The claims of the patent, the first four only of which are alleged to have been infringed, are as follows: "(1) A diving-flue cooking-stove with the exitflue so constructed as to inclose on the sides and bottom the culinary boiler or hot-water reservoir, B; (2) a diving-flue cooking-stove with the exit-flue constructed across the bottom and up the rear upright side of the culinary boiler or hot-water reservoir, B; (3) a diving-flue cooking-stove constructed with an exit-passage, F, below the top of the oven, and an exit-flue, E, E', in combination with an uncased reservoir, B, attached to the rear of the stove, and placed just above such exit passage, and so arranged that the gases of combustion, in passing through such exit-flue, will impinge upon or come in direct contact with said reservoir, substantially as and for the purposes hereinbefore specified; (4) an exit-passage, F, constructed in the rear of a diving

flue cooking-stove and below the top' of the oven, in combination with an uncased reservoir, B, attached to the rear of the stove, the bottom of which reservoir is also below the top of the oven, and so arranged that the gases of combustion will come in contact with and heat such reservoir by a direct draft from the fire-box to the smoke-pipe; (5) in a cooking-stove wherein the rear-end vertical plate, or a portion of the same, has been removed for the purpose of heating a reservoir placed in the rear thereof, the shield-plate, w, w, in combination with the uncased reservoir, B, and the rear-end vertical flues, K, L, and L', substantially as and for the purposes hereinbefore described and specified."

The defendant's stove has three flues and an exit passage below the top of the oven, and a reservoir, the bottom of which is below the top of the oven; but no part of the rear-end vertical plate is removed so as to allow the gases of combustion to come into direct contact with the front of the reservoir, nor is any such plate employed as the plate, w, w, of the patent, but there is a dead air-space between the rear plate of the flue and the front of the reservoir. The exit-flue is not a narrow one, carried across the middle of the bottom of the reservoir, as in the patent, but the products of combustion, on leaving the flue-space, pass into a chamber beneath the reservoir, the area of which is co-extensive with the entire surface of the bottom of the reservoir; and the vertical passage out of such chamber is not one outside of the rear of the reservoir, but is one in and through the body of the reservoir, and removable with it. In view of the earlier patents put in evidence, we are of opinion that the four claims in question must be limited to a structure in which the front of the reservoir has no air-space in front of it, and in which the exit-flue does not expand into a chamber at the bottom of the reservoir, and in which the vertical part of the exit-flue does not pass up through the reservoir. Under this construction there is no infringement of No. 3,815.

Claim 1, in requiring that the exit-flue shall "inclose on the sides and bottom" the reservoir, requires, in the language of the text of the specification, that it shall extend "down the front, under the bottom and up the rear" of the reservoir; and it does not admit of an air-space in front of the reservoir; nor is it limited to what is called a low-down boiler or reservoir. The Getz patent of 1840 shows an exit-flue passing under the bottom and up the rear side of a reservoir. The Spaulding or Paris patent of 1858 shows a divingflue inclosing the bottom and one of the sides of a reservoir.

Claim 2 is not limited to a low-down boiler or reservoir. If a stove with an exit-flue constructed across the bottom and up the rear upright side of a boiler or reservoir existed before, there was nothing patentable in applying such construction to a diving-flue stove. The combination of exit-flue and reservoir with which claim 2 is concerned has no patentable relation to the arrangement of the internal flues of the stove. The Getz patent of 1840 shows an exit-flue extending across the bottom and up the rear upright side of a boiler. In the Stewart patent of 1859 the products of combustion enter a chamber under the reservoir and thence pass off by a pipe embraced within the walls of the reservoir. The exit-flue of claim 2 must, therefore, be limited to one which passes under the bottom of the reservoir without expanding into a chamber substantially co-extensive with the area of the bottom of the reservoir, as in the defendant's stove and in the Stewart patent of 1859; and also to one in which the escape-pipe is outside of the rear wall of the reservoir and not within the reservoir, as in the defendant's stove and in the Stewart patent of 1859.

Claim 3 adds to claim 2 only the feature of having the exit-passage or exitorifice into the exit-flue below the top of the oven. There is no patentable relation between the combination of exit-flue and reservoir and the location of the exit-passage with reference to the oven, in view of the state of the art In the Stewart patent of 1859 the exit-opening was on a level with the top of

the oven and led into a chamber under the reservoir. In the Spaulding or Paris patent of 1858, and in the Bussey patent of 1865, the bottom of the reservoir was below the top of the oven. There was no invention in causing the gases to act on a low-down reservoir in the same way in which they had acted before on an elevated reservoir; and no invention in lowering the exit opening to correspond with the depression of the reservoir, even though the incidental effect was to heat by a direct draft, at the same time, the reservoir and the rear side of the oven.

Claim 4 adds to claim 3 only the feature of heating the reservoir by a direct draft from the fire-box to the smoke-pipe. This, however, is only a statement of the effect produced in a structure made according to the first three claims. In the Getz patent of 1840, and in the Stewart patent of 1859, the exit-pipe was in the rear of the reservoir, and the gases were brought into contact with the bottom of the reservoir, and it was heated by a direct draft. There is really nothing in claim 4 beyond what is found in claim 3.

* *

The specification of No. 142,933 is as follows: "Our invention relates to that class of cooking-stoves in which a water reservoir is situated at the rear end of the stove; and it consists in the arrangement of the reservoir upon an extended support at the rear of the stove, so that an air-chamber, opening at its top into the air of the room, is left between the back-plate of the stove and the front of the reservoir, thereby protecting the front of the same from becoming burned out by being in direct contact with the heat from the fire. It also consists in a broad sheet-flue arranged under the reservoir, the heated air for which enters through a small passage in the back plate of the stove, and, after circulating in said flue, passes out through the small opening in the rear thereof, all as more fully hereinafter set forth. * Figure 1 is a longitudinal vertical section of our stove; figure 2 is a transverse vertical section of the same through the water-reservoir; figure 3 is a plan view of the reservoir; and figure 4 is a front view of the sheet-flue under the bottom of the reservoir. A represents the top plate of the stove. B is the oven; C, the water-reservoir; D, the center one of the three flues of the stove; and E, the exit-flue, located in the rear of the reservoir, C. This reservoir is located upon a support therefor, which extends rearward from a point about half-way between the top and bottom plates of the stove, and which may either be attached to or form part of the stove, and a sheet-flue, G, is provided in the same under the bottom of the reservoir, C. The heat, entering this flue, passes through the small center passage, a, in the stove-back, I. It is there spread and retained under the reservoir until it gradually ascends through the small passage or exit-flue, E. By this construction the rapid exit of the heated air from under the reservoir is prevented, and the heat, being retained under the bottom of the reservoir, causes the water in the same to become hot in a short time. The reservoir, C, is so arranged with respect to the backplate, I, of the stove that an air-space, b, communicating with the air of the room at the top, is left between the front of the reservoir and the back-plate. By this means the outside air will pass down between the back-plate and front of the reservoir and prevent the front of the reservoir from burning out, which would be the case if the parts were in direct contact, especially when the water in the reservoir becomes low. In the ordinary method the flame is made to strike directly upon the front surface of the reservoir, thereby rendering it liable to crack while replenishing with cold water upon the heated plates. The opening, a, in the back-plate, I, of the stove is of the same width as the center-flue, D, and the products of combustion pass through said opening into the sheet-flue, G, which thus has a contracted entrance and a contracted exit. When using the direct draft the damper, d, of the center flue, D, is turned downward and rests against the back-oven plate, as shown by the dotted lines in figure 1. At such times the heat passes down the center-flus, D, of the back, through the opening, a, in the back-plate, I, into the sheet-flue, G, under

the bottom of the reservoir, and out of the exit-flue, E. When the indirect draft is used, the damper, d, occupies the position shown in figure 1, and at such times the heat passes down the usual side-flues and under the bottom of the oven to the front of the stove, where it turns into the center-flue, D, and passes back through the opening, a, to the sheet-flue, G, under the bottom of the reservoir and out of the exit-flue. With a stove thus constructed, the reservoir is heated almost entirely from the bottom, and the heat acts upon

the entire surface of the bottom of the reservoir, and when the reservoir is but partially filled there is no danger of the heat acting against, and burning out, the top part of the front side of the reservoir. We do not claim under this patent a flue-shell and rear central extension that is detachable from the stove-body by means of hooks on the one and catches or pins on the other, nor do we specifically claim a reservoir with a flue in its rear, as these ele ments of invention are the subject of a separate application for a patent, now pending; neither do we wish to be understood as claiming the arrangement

of the reservoir and flues for heating the same in front of the fire-box of the stove, as shown in our patent of May 6, 1873, No. 138,682."

The claims of No. 142,933 are two in number, as follows, and the infringement of both is admitted: "(1) The combination with the back-plate, I, of the cooking-stove, A, of the reservoir, C, arranged on a support about midway between the top and bottom plates of the stove, and the air-chamber, b, between the stove-back and reservoir-front, open at the top and communicating with the air in the room, substantially as and for the purposes set forth. (2) The combination, with the stove, A, and reservoir, C, of the small opening, a, the sheet-flue, G, under the entire bottom of the reservoir, and the small exit-passage or pipe, E, all substantially as and for the purposes herein set forth."

The point of invention in claim 1 is in so arranging the reservoir as to have an air space between the front plate of the reservoir and the back plate of the stove, to a sufficient extent to prevent the flame from striking against the upper part of the front plate of the reservoir, which it would do if the upper part of the back plate of the stove were cut away, and there were no such air-space. It is the upper part of the front side of the reservoir which, as the specification states, is liable to the burned out by the direct action of the flame, as the water in the reservoir is lowered. In the McDowell patent of 1871 all the upper part of the reservoir is protected by an air-space, open at the top, between the reservoir and the stove.

The point of invention in claim 2 is to take the gases through a small opening into a broad sheet-flue under the bottom of a reservoir and out through another small opening in the rear, so that they will circulate in the broad flue and act on the entire surface of the bottom of the reservoir. The Stewart patent of 1859 shows the same arrangement with an elevated reservoir, but there is no invention in applying it to a low-down reservoir. The Tiffany patent of 1869 shows the same arrangement with a low-down reservoir.

The specification of No. 142,934 says: "The nature of our invention consists in the construction and arrangement of a cooking-stove with a portable basepan or flue-shell, and the means for attaching the same, as will be hereinafter more fully set forth. * ** Figure 1 is a longitudinal vertical section of our improved cooking-stove; figure 2 is a side view of the rear end of the same; figure 3 is a plain view of a loose cover or plate for the base-pan; and figure 4 is a perspective view of the portable base-pan or flue-shell. A represents the main baking-oven of the stove; B is the top flue; B, B, the vertical and horizontal side flues; C is the center flue; D is the base-pan or flue-shell; E, the exit-flue passing up the rear side of the reservoir; F is the reservoir; G, the warming-closet; H, the damper; I, the fire-chamber; and J, the division-plate. When using the direct draft, the damper, H, occupies a line parallel with the back plate of the main oven, hanging down in the center flue of the back part of the stove. At such time the products of combustion pass from the fire chamber, I, along the top flue, B, and down the center flue, between the back oven-plate and the division-plate J, into the base-pan, D, and out of the exit-flue, E. When using the indirect draft the damper, H, occupies the position shown in figure 1. At such time the products of combustion pass over the top oven-plate flue, B, and down the vertical end-flues, B', into corresponding flues at the bottom, making the turn into the center flue of the bottom at C, through said bottom center flue, into and through the rear center flue, through the division-plate, J, into the base-pan flue, Ď, and out of exit-flue, E, so that, whether using the direct or indirect draft, the reservoir is heated only on its bottom surface. The base-pan, D, is made separate from the stove, and provided on each side with a hook-projection, a, to be fastened on a pin, b, projecting from the side of the stove. By this means the base-pan can readily be attached and detached; and when attached it fits in the upper end and forms the top of the warming-oven, G. K represents a