332 7EPSBAL BEFOBTEB. �stea,m exeris a pressure upon the whole area; upon the front aide of the piston the steam exerts a force upon the whole area, less the area of the piston-rod, upon -which small area is only exerted the pressure of the atmosphere. Therefore, steam of greater than atmospheric pressure would assist in driving the piston forward, and expelling the lubricant hy this small difference." �There is, however, some slight assistance by the force of steam. It will be observed that the specification acknowl- edges steam as one of the propelling forces. �This is the state of the facts : The patentee had invented a lubricator, the efficient agent in which was the pressure of steam, as he supposed. The device was patented as for a lubricator acting by steam pressure. Subsequent investiga- tions led him to the conclusion that although steam rendered slight assistance, hydrostatic pressure was the active agent. He made a new arrangment of parts in which the latter prin- oiple only was used, and the second device was patented. The patentee now seeks, by a re-issue of the first patent, to obtain a pp,tent from 1869 which shall cover the method of feeding a lubricant by means of hydrostatic pressure alone, operating through devices substantially as shown. �It is not contended that the patentee bas not a right to introduee in bis re-issue the vertical pipe which had been left out of the drawings, and to claim that arrangement of ail . the parts of bis device which he actually invented, whereby the lubricant was fed by hydrostatic pressure or steam press- ure, or both ; in other words, the first claim of the re-issue. But it is insisted that an introduction into the claims of mat- ter which discards steam pressure, with the piston, as an agent for feeding the oil, and thus changes the nature of the invention which was originaUy applied for, is an introduc- tion of new matter. I am of opinion that the last two claims, if construed in any other way than by such limita- tions as shall confine them to the mechanism specified in the first claim, substantially as described, are, under the recent decisions of the supreme court, an undue enlargement of the original patent. ����
