Fig. 552.
THE PULSOMETER.
The original pulsometer was an instrument called by that name for measuring the force and frequency of the pulse; it was invented in 1626 by Santovio of Padua, Italy. The term has been largely applied to a form of vacuum pump, soon hereafter to be described; this has a pulsative action—like a heart beat. The pulsometer, the aqua-thruster, the pulsator, and other regular double acting two oval reservoirs (one filling while the other is discharging) automatic condensing steam vacuum pumps are all patterned after the Thomas Savery pump shown in Fig. [552]; this was patented in England in 1698. It is thus described:
“The upper end of the suction pipe shown at the mouth of the pit consists of two branches, which are connected to similar branches on the lower part of the forcing pipe N. The suction valves are at B A and the forcing ones at E F, all opening upwards. Between these valves two short curved tubes connect the bottoms of the receiver I M with the branches, as represented, and two other bent tubes, P Q, unite the top of the receivers with the boiler H. On top of this boiler, and forming a part of it, is a stout round plate, having two openings of the same size as the bore of the tubes last mentioned. In these openings the two steam tubes P Q terminate. Between the openings, and on the under side of the plate, is a movable disk, which by a short arm is connected to an axle and moved by the long lever shown on the top of the boiler; so that by moving this lever the disk can be made to open or close either opening, so as to admit or exclude steam from the receivers, and answering every purpose of a three-way cock.
Fig. 553.
“The face of the disk is ground smooth, so as to fit close to the under side of the plate, against which it is pressed by the steam. The perpendicular axle by which the disk is turned passes through the plate, and the opening is made tight by a stuffing-box. (The plate and movable disk are represented in the small figure at the top, one of the openings, Q, being covered by the disk and the other, P, exposed.) A small cistern, U, is placed over the receivers, and kept supplied with cold water from the forcing pipe by means of a ball cock, viz.: a cock that is opened and shut by a ball floating in the cistern. From the bottom of this cistern a short pipe, T, proceeds; and to it is connected, by a swivel joint or stuffing-box, another one at right angles. This pipe furnishes water to condense the steam in the receivers, over both of which it can be moved by the rod attached to the plug of the cock as shown in the figure. The upper cistern denotes the place where the water raised by the engine is to be discharged.