Page:Federal Reporter, 1st Series, Volume 5.djvu/465

 WILT V. GMEB. 453 �eomplish the same result in the elevation of the staok of trays, from a point in or on the lowermost tray thereof, so as to permit the insertion of a fresh tray at the bottom ? Thie question can be best answered by referring to the opinions of the courts npon the meaning of the term "mechanical equiv- alents." Thus, in Carter y. Baker, 4 Pisher's Pat. Cases, 404, Mr. Justice Sawyer says : "When, in mechanics, onc device does a. partieular thing, or accomplishes a partieulai resuit, every other device known and med in mechanics, which skilled and experienced workmen know will produce the same resuit, or do the same partieular thing, is a known mechan- ical substitute for the first device mentioned for doing the same thing, or accomplishing the same resuit, although the first device may never have been detached from its work and the second one put in its place. It is sufficient to constitute known mechanical substitutes, that when a skilful mechanic sees one device doing a partieular thing, that he knows the other devices, whose uses he ia acquainted with, will do the same thing." �Mr. Justice Curtis, a high authorifcy upon the subject of patent law, in Poster v. Moore, 1 Curtis, 279, holds that "the doctrine of mechanical equivalents * * * is not confined by the patent law to those elements which are strictly known as such in the science of mechanics, but that.it embracea those substitutions which, as a matter of judgment in con- struction, may be employed to accomplish the same end." See, also, as illustrating the principle of mechanical equiva- lents, the opinion of Alderson, B., in Mffrgan v. Seaward, Web. Pat. Cas. 170. �We are now in a condition to make the further and final inquiry, whether the defendant bas infringed the rights se- cured to the complainant by bis patent No. 190,368. �The two machines, as will be manifest upon referenco to the specifications and drawings in the respective patents, are alike in principle, having a staek in each case composed of sections of trays, fitting upon and into each other, the outer wall of which makes up and forms the exterior of said stack ûr drying-house ; and they are also alike in their purpose and ����