The opinion of the court was delivered by: Matthews, J.
G. G. Symes, Geo. Harding, and F. T. Chambers, for plaintiffs in error.
B. F. Thurston, Thos. Macon, E. T. Wells, R. T. McNeal, and Whit. M. Grant, for defendants in error.
This was an action at law to recover damages for an alleged infringement of letters patent No. 121,385, issued November 28, 1871, to the plaintiffs, for an improvement in furnaces for smelting lead and other ores. There were several defenses set up by way of pleas, but the two chiefly relied on were that 'the plaintiffs' pretended invention' had been described 'in a certain printed publication entitled 'System der Mettallurgie,' von Dr. J. B. Karsten, published at Berlin, Prussia, in 1831-32, in 5 volumes, with an atlas of plates, I., at pages 315, 316, 317, 318, 319, 320, 321, and 322, of volume 3, and pages 150 to 166, both inclusive, and 166 to 180, both inclusive, of volume 5, and figures 479, 480, 481, 482, 483, 484, 473, 474, 475, on plate XXI., and figures 850 to 868, both inclusive, of plate XLI. of the atlas accompanying said work;' and, secondly, that, in view of the state of the art at the date of the alleged invention, the improvement was not patentable, as not requiring the exercise of invention. The issues came on for trial before a jury, and there was a verdict for the defendants, and judgment thereon, to reverse which this writ of error is brought.
It appears from the bill of exceptions that the plaintiffs read in evidence the patent sued on, the substantial part of the specifications attached to which was as follows: 'The object of this invention is to provide a novel, simple, and improved method of tapping or withdrawing lead and other metals, when in a molten state, from the bottom of a smelting furnace, so that the metal may be obtained therefrom in a clean state, and also that the formation of hard matters or incrustations on the sides and bottom of the furnace may be avoided. The nature of this invention consist in the use or employment of a basin of suitable dimensions, located a short distance from one side of the furnace, and at a suitable elevation above the bottom of the furnace; which said basin is connected with the furnace by means of a tube which extends from the bottom of the basin to the bottom of the furnace. As the molten metal fills the lower part of the furnace it rises to the same level in the tube until it reaches the basin, from whence it may be removed as clean metal. To enable others skilled in the art to make and use our invention, we will proceed more particularly to describe the same: The figure represents a sectional elevation of a portion of a smelting furnace with our improvements. A represents the furnace, which may be of ordinary or common construction. B is a basin of suitable dimensions, located at the top of an extension built on one side of the furnance, and at a suitable elevation above the bottom of the furnace. The basin may be constructed of any material suitable for receiving and holding the molten metal. Extending from the bottom of the basin, B, to the bottom of the furnance, A, through the above mentioned extension, is a tube, C, which connects the basin with the furnace, and which may be made of iron, clay, or other material suitable for the purpose. The metal as it melts falls to the bottom of the furnace. As the surface of the molten metal rises within the furnace it rises to the same level in the bube, C, until it reaches the basin, B, from which it may be removed with a ladle. The advantages of this invention are obvious, as by this means the metal is tapped or withdrawn from the furnance free from impurities; and it will also be seen that the difficulties arising from the formation of hard matter or incrustations on the bottom or sides of the furnace, occasioned by the usual method of drawing off a large quantity of molten metal at one time, are obviated. Having thus described our invention, what we claim as new, and desire to secure by letters patent of the United States, is the method of tapping or withdrawing molten lead or other metals from a smelting furnace by means of the basin, B, and tube or connection, C, in combination with the furnace, substantially as shown and described.'
The drawing referred to is as follows:
[NOTE: MATERIAL SET AT THIS POINT IS NOT DISPLAYABLE (GRAPHIC OR TABULAR MATERIAL)]
Albert Arents, one of the plaintiffs, testified to his own qualifications as an expert in the art of smelting, and also 'that the obtaining of clean metal from the side of a furnace of ordinary construction, automatically, by the means described in the specifications in the patent, was novel and useful, and a great improvement over the old mthod of withdrawing clean metal from smelting furnaces; that the specifications were sufficiently full, clear, and precise to enable persons skilled in the art to which they appertained, to-wit, the art of smelting, to construct a furnace which would produce the useful result claimed by the patent, to-wit, the obtaining clean metal automatically from a smelting furnance, when in operation of ordinary construction; that a furnace of ordinary construction, as it existed at the date of plaintiffs' patent, as defined by the art of smelting, so far as is material to this case, consisted of an inner hearth, with an open breast or sump, into which the molten masses of the furnace, when fused, collected and settled according to their specific gravities; that the front of a smelting furnace was that part of the furnace where the slag ran and was handled by the smelter; that the back of the furnace was opposite to the front, and that those parts of the furnace to the right and left were known and called the 'sides;' that the slag ran off through a spout over the open breast of the furnace in front, and the clean metal was tapped periodically from a tap-hold at the bottom of and from the side of the furnace; that each part in the construction of the furnace had its particular functions, which were important, as understood and known and taught in the art of smelting at that time, to-wit: the front was the working door of the furnace, and was where the slag ran off and was handled; the back and sides where the tuyeres were situated, through which the blast was forced into the furnace, and the clean metal was periodically drawn or tapped from one side or other of the furnace.'
The plaintiff then introduced a model on the scale of one inch to the foot, in sections, showing what a furnace of ordinary construction was at the date of the patent, as knwon in the art of smelting, showing the improvement of the plaintiffs, and the old mode of tapping, of which the following are drawings:
[NOTE: MATERIAL SET AT THIS POINT IS NOT DISPLAYABLE (GRAPHIC OR TABULAR MATERIAL)] [NOTE: MATERIAL SET AT THIS POINT IS NOT DISPLAYABLE (GRAPHIC OR TABULAR MATERIAL)]
The plaintiffs then corroborated this testimony of Arents by that of numerous experts, and gave evidence tending to prove infringement by the defendants, and rested their case.
The defendants put in evidence certain extracts from the text and illustrative drawings of smelting furnaces of the treatise upon metallurgy by Dr. J. B. Karsten, published at Berlin in 1831-32, mentioned in the plea, translated as follows:
'(318) The forehearth is that part of the crucible projecting in front of the fire-walls of the furnace. Crucible furnaces are those shaft furnaces in which the curcible is entirely one the inside. They are divided into eye-crucible furnaces and tap-crucible furnaces. The former have an eye in the front wall from which the slag flows continuously, the metal and matter being tapped off at intervals into basins. The tap-crucibles furnaces are those in which the metal, matte, and slag are all tapped off from time to time. Sump furnaces are those shaft furnaces in which the crucible is partly in the furnace and partly in front of the furnace. The slag runs off continuously over the forehearth. The metal and matte are tapped off into receiving vessels or tap-basins. Sometimes the sump furnaces are not provided with tap-basins, and the metal in them is dipped with ladles direct from the forehearth. Spur or channel furnaces are shaft furnaces without a crucible. The molten contents flow through the eye directly from the furnace hearth into receiving vessels. These different furnaces can be more advantageously studied from drawings than from written descriptions.
'(319) In some countries the crucible furnace is preferred; in others the sump furnace. It is not advisable to use the channel furnace when clean metal is produced. With this furnace the metal is not protected from oxidation. It is used chiefly in smelting copper ores, with a view to producing copper matte. The drawings, figures 461 to 463, represent an eye-crucible furnace. The slag runs continuously through a hole in the front wall. The metal and matte are tapped off at intervals through a hole in the side of the crucible. The drawings, figures 464 to 466, represent an eye-crucible furnace, which differs from the former in that the tap-hole is in the front wall and at the bottom of the crucible. The drawings, figures 467 to 469, represent a tapcrucible furnace. The metal, matte, and slag are tapped off from time to time into receiving basins. The drawings, figures 470 to 472, represent an eye ...