Nikola Tesla U.S. Patent 514,169 - Reciprocating Engine Patent Wrapper Page 16

4 The main supply pipe L for steam or compressed air leads in to this chamber, and the two pipes that lead to the cylinder A run from the said chamber, oil cups M being con ve ni ent ly arranged to deliver oil into the said pipes for lubricating the piston. In the particular form of engine shown, the jacket K which ort a ins the cylinder I is provided with a flange N by which it is screwed to the end of the cylinder A. A small chamber O is thus formed which has air vents P in its sides and drip pipes a leading out from it through which the oil which collects in it is carried off. P To explain now the operat ion of the device above. described. In the position of the parts shown, or when the piston is at the middle point of its stroke, the plunger J is at the center of the cylinder I and the air on both sides of the same is at the normal pressure of the outside atmosphere. If a source of steam or compressed air be then connected to the inlet ports C C of the cylinder A and a movement be imparted to the piston as by a sudden blow, the latter is caused to reciprocate in a manner well un derstoo d. The movement of the piston in either direction ceases when the force tending to impel it and the momentum which it has acquired are cainterbalanced by the in creasing pressure of the steam or compressed air in that end of the cylinder towards which it is moving and as in 61