Page:Federal Reporter, 1st Series, Volume 4.djvu/467

 STEBBINS, ETC., KLEVATOB MANUF'g CO. ». 8TEBBIK3. 453 �As the piston, G, rises in the hoUow rod or cylinder,/, the dead-water resting in the pipe below the cock enter s through the valve, g, and opening, g\ into and fills the cylinder,/. Let ub suppose the elevator has reached the thlrd floor of the build- ing and some additional weight is added to the load, and the main piston, D, is unable to rise further, water is admitted through the opening, a', and under the piston, P. This piston then rises, and as the valve, g, closes and prevents the escape of the water from under the piston. G, the piston, F, carries •with it the piston, G, and piston rod, I, and an additional power is thus added to the piston, D, to aid in raising the elevator. By this construction it is evident that I am able to bring the auxiliary piston, F, into immediate action when needed. It remains in position to receive the hydraulic press- ure, while the piston, G, and rod, I, move up with the piston, D, and, practically, become an elongated rod to the piston, F, ready to catch the pressure and come to the aid of piston, D, whenever additional aid is required." �An examination of this specification in connection with the specification in patent No. 132,111 shows that the views of the defendant's export must prevail over those of ' the plaintiff's expert, and ihat the doctrine of mechanical equiv- alents cannot be successfully invoked in this case in favor of the plaintiff. The specification of patent No. 132,111 admits that two cylinders had before been used to elevate the load, and that the pressure in both cylinders was appliedin ail cases. Of course both cylinders were always in operative connection with the device to be driven by the pistons. The only new idea in common in patent No. 132,111 and patent No. 172,896, is the idea of employing the power of either one or two cylinders so as to economize water. One patent does it by one mode of construction and operation, and the other by another, cylinders and pistons in hydraulic elevators being old, to the extent just indicated. �It is not alleged that the defendant has infringed the second claim of patent No. 132,111, and it foUows from the foregoing considerations that he has not infringed the first claim of ����