Page:The Kinematics of Machinery.djvu/387

 RAMELLI, BE ALE. 365

Ilamelli, described by him in 1588.* It is a combination of four reduced turning blocks, in which d is the driver, the coupler b is omitted and the block c force-closed. Its formula is therefore

$$ 4 \left \lbrace \left ( C''_3 P^{\bot} \right )^{\frac{a}{d}}-b-\frac{c}{2} \right \rbrace $$

The springs shown in the figure have often been used for the force- closure. Eamelli himself, however, placed the machine with the centre of the inner drum d above that of the chamber, and contented himself with such closure as he could obtain from the weight of the blocks. The chamber a is made a hollow cylinder, and there is higher pairing between it and the blocks. There have been repeated re-inventions of this pump, among others I may mention the steam-engine of Borrief which had four blocks and springs, and Caméré's pump, which lias only two pistons, but in which the closure is still effected by springs.^

Fig. 4, PL XIX represents a machine very similar to that of Ramelli. It has been proposed in England as a steam-engine or pump by Jones and Shirreff (1856) and in America as a steam- engine by Ortlieb and White (1867). It is a treble chain (CgP- 1 -)* reduced by b. The higher pairing between a and c rendered necessary by the omission of the coupler is quite correctly made. The first- named inventors leave the cylinder 2 free to revolve, in order to diminish as far as possible the friction between it and the blocks.

Fig. 1, PL XX., shows another arrangement of the same me- chanism designed by Beale for a steam-engine || and actually applied by him to the propulsion of a vessel. Dalgety and Ledier used it for a pump in 1854.1T Here the blocks c are made com- pletely cylindrical and left entirely free to roll. That the machine was unsuccessful cannot be wondered at, for the higher pairing used at all the joints rendered it impossible that they should remain steam-tight.


 * Ramelli, Artefidose Machine (1588), pp. 58 and 167.

t Bataille et Jullien, Mack, d Fapeur, 1847, i., p. 445, pi. xi.

Propagation Industrielle, vol. iv., 1869, p. 337.

Newton, London Journal of Arts, &c., new series, vol. vi., 1857, p. 9. Schweizerische Polytcchn. Zcitschrift, vol. ii., 1857, p. 8.

Engine, p. 392. Beale appears to have employed centrifugal force-closure between the pistons c and the chamber.
 * Bataille et Jullien, Machine a Vapeur, vol. i., 1847, p. 444. Bourne, Steam


 * [ Propagation Industrielle^ vol. iv., 1869, p. 84.