604 FBDEBAL BEPOBTSB. �circuit for each signal. The System of Thomas S. Hall, which was used on the Harlem Eailroad in 1871, moved the signais by stationary batteries, and required two batteries to operate each signal. �The object of the System which Pope patented was to operate automatically a series of signais, in definite and pre- determined succession, by the passage of a train, making use of a single battery. The patentee says in his specification : "My invention consists in a peculiar arrangement of electric circuits, in combination with a battery, and with two or more circuit closers, operated by moving trains or otherwise, whereby a series of two or more visual or audible signais, eituated at intervais along the line of a railroad, may be operated by currents of eleotricity derived from a single bat- tery, thereby obviating the inconvenience and expense of employing, as heretofore, one or more separate batteries, situated at or near each signal, for the purpose of actuating the same." The record shows that the invention was a new combination of old devices whereby a novel and useful resuit was produced, and was patentable. It is assumed that the same invention was placed on the Eastern Eailroad of Mas- sachusetts by the defendant, a corporation which has been engaged in the manufacture and erection, upon different roads, of signaling apparatus constructed in accordance with various patents of Thomas S. Hall, and that the change which was made, whereby the earth was used as a part of the circuit, was not a material change or modification of the invention. Letters patent to Hall & Snow, No. 165,570, dated July 13, 1875, describe the defendant's method of electric circuits. �Upon this assumption the main question in the case is that of priority of invention, for it wUl be manifest that Pope and Hall were each independent inventors of the one -battery Sys- tem, and that each mentally conceived of the same plan, in substance, in the summer and fall of 1872. Hall is the father of the plan of electric railroad signaling apparatus, which is in use in this country, and in 1872 was actively engaged in studies and experimenta, and in the praotical ��� �
