296 FEDERAL REPORTER. �cation between the two is had by an angular passage, into an enlarged continuation of which is tapped the upper and longer leg of an inverted siphon tube, whose short leg terminates near the top of the cup and close to the sides thereof usually observed. The cup itself is a glass cylinder, and has no external indicator. One of the claims of the patent (the third) is : "In a displacement lubricator, suhstantially as described, the combination, with the elevated water reservoir and suspended cil cup, of the inverted siphon tube, through which the water passes into the said oil cup, suhstantially as described and shown." There is no separate claim in this patent for the inverted siphon tube. The advantage of having the tube in the form of an inverted siphon is thus set forth in the specifications of this Een- chard patent : "If the tube were straight, the water in its descent would press up the oil, which is of less specifie gravity, and the water and the oil would thus gradually change places ; but by making it in the shape of an inverted siphon, and being always full of water, the oil cannot force its way down through the short leg, and hence takes another outlet. " In other words, it effectually prevents the escape of oil by ascent through the tube into the condensing chamber, and forces it through the duct prepared for it into the steam-pijpe or machine to be lubricated. �As early as January 2, 1872, a patent for an improvement in lubricators, No. 122,3I>1, was granted to William A. Clark, Westville, Connecticut, which consisted of a metallic condensing chamber, super- imposed upon a glass oil cup, connected by means of a straight tube, depending perpendicularly, to convey the water into the oil cup to a point very near its bottom, below the water level. Between the two chambers was the arm or trunk, by which the lubricator was attached to the steam-pipe, and by means of a single passage through which steam was admitted to the condenser, and the oil, forced upward from the oil cup, flowed into the steam-pipe, Subsequently, March 6, 1877, but still prior to the date of the Parshall or complainant's pat- ent, there was issued to Clark an additional patent. No. 187,964, for an improvement in lubricators. In this he substituted for the glass oil cup one made of metal, with a glass indicator, external to it, but freely communicating with it at both extremities. The water tube, which in his previous instrument passes vertically and directly from the condenser to oil cup, was now made to pass by a right angle hor- izontally through the intervening trunk towards the gauged tube or indicator, where it terminated by opening upwards into a small chamber, in which was sealed a light check-valve. From this cham- ��� �
