BROADNA.X ». CBNXEAIi STOOK YARD ft TRANSIT 00. 217 �according to the model and specifitJatioHS filed, it "will operate BuccessfuUy^ as a practical and ueeful thing, the inventer h&e satisôed the law, and hîs patent is valid. He is not bound by law to eonstruot it, in order to preserve bis patent. " �In our investigation into the design and aim of the patent "we are favored with the testimony of the patentee himself, who is also eomplainant in the case, and who ought to, be a competent authority on the question of what the inventer intended to embrace. He saye, at folio 552 of the record, that "the essential principle of my [his] invention consista of a tank enclosed in a hot chamber, by which the beat can be kept in the material without danger of burning it, and of an instrument introduced into the tank by •which the material can be continually stirred or agitated in such manner as to continually present new particles of the material under treat- ment to the drying surface of the tank, and to the free beat contained in the tank." �Accepting this as an accurate description of the complain- ant's patent, the remaining questions are: (1) does the de- fendant corporation infringe the combination? and (2,) if they are infringers, is the combination of the eomplainant new ? The defendants disclose, in their answer and by their testimony, the mechanism which they employ in rendering the fat and drying the refuse. They allege that upright boilers are used in one portion of their factory, separate and apart from the place where the scraps or residuum are dried. "In these boilers," it is further stated, "the animal matter is placed, and steam is injeoted therein in the ordinary way until the lard or tallow is boiled out. The lard or tallow is then drawn off from above the water contained in the boiler through any ordinary stop-cock in the side of the boiler. Tho water isthen drawn off, and the refuse animal matter isdumped into a tank underneath, from which it is taken and put into an ordinary screw-press, for the purpose of expelling the ex- cess of water. The scrap or residuum is then taken to another part of the factory and placed in an ordinary hori- zontal steam-jacketed boiler. In this boiler there is a hori- zontal shaf t with radial arms. The steam ia the« let into the ����
