616 



MECHANICAL IMPROVEMENTS AND INVENTIONS. 



might be employed in mechanics. He shows 

 that a column of fluid, with valves, is perfectly 

 analogous to a ratchet-gear. 



Among the many methods devised of late 

 for propelling street-cars by other power than 

 that of horses, the invention of M. M6karski, 

 which was put into practical use this last year 

 in Paris, deserves special notice. The motive 

 power is compressed air, which must be sup- 

 plied from reservoirs at the end of the line, 

 filled by expansive condensing engines, which 

 work compressing pumps with a power of 

 compressing air to a pressure of 25 or 30 

 atmospheres. The air is heated as used by 

 passing through a column of hot water, which, 

 when injected into the heater, has a tempera- 

 ture of 170 to 180 0., and thus becomes 

 saturated with steam at a high temperature : 

 70 or 80 litres of water are sufficient for 1,500 

 litres of air. As the pressure in the reservoirs 

 is not constant in degree, a special apparatus 

 regulates the supply to the cylinders. The 

 mingled air and steam passes from the heater 

 through a clack valve, which closes over the 

 discharge vent, and which is kept open by a 

 certain degree of pressure upon a piston con- 

 nected with it ; and by the discharge the press- 

 ure upon the piston is reversed, and a force 

 is exerted upon the valve which tends to close 

 it. The pressure upon the piston is equal to 

 the pressure of the compressed air in the regu- 

 lator ; and the pressure of the air and steam 

 in the cylinders is thus regulated automatically 

 to a certain point. It is, furthermore, regulated 

 by a small plunger, which the driver works 

 with a hand-wheel. The running-gear is similar 

 to that of a locomotive-engine. Air saturated 

 with steam is highly expansive, and allows of 

 a long run with a small quantity of air: about 

 11 cubic feet of compressed air per mile, at the 

 pressure of 25 atmospheres, has been found 

 sufficient. The steam does not exhaust, but, 

 condensing in the cylinders, restores to the air 

 its latent heat. After each course the reser- 

 voirs, of which there are several, situated un- 

 der the floor of the car and connected by 

 copper pipes, are pumped full of compressed 

 air, and the water in the heater is reheated by 

 steam conducted through a flexible hose. The 

 management of this tram-car is much more 

 perfect than that of a horse-car ; the speed 

 may be increased or slackened, the car stopped 

 or reversed, almost instantly, at the will of the 

 driver. 



Steam tram-cars upon the model of the ones 

 which were first introduced by the Merry- 

 weathers, of London, have been in use in Paris 

 for some time. Their construction is light, and 

 their working safe and economical ; but the es- 

 cape of smoke and steam would be a serious 

 objection in most cities. An engine invented 

 by Mr. Hughes, in England, is noiseless, and 

 the steam is condensed into a tank, which can 

 be emptied after each completed course. 



Another new method for driving street-cars 

 has been invented by M. L. Rousseau, of Brus- 



sels. The motive agent is compressed water, 

 whose elasticity, by the aid of an hydraulic 

 capstan, or the numerous similar apparatus, or 

 any other mechanism which is employed to 

 convert hydraulic pressure into motion, is 

 brought to bear on the running-gear of the 

 cars. The water under pressure is supplied by 

 a powerful engine to a reservoir connected 

 with a pipe, which is laid under the track for 

 its entire length, with taps at intervals for sup- 

 plying the cars with the compressed water. 

 The still greater elasticity of air is utilized in 

 connection with the compressed water. Con- 

 necting with the cylinders containing the water, 

 either directly or through a piston, is a receiver 

 containing air, which, when the cylinders are 

 charged, has a pressure of 20 to 30 atmospheres. 

 It is the water which comes in contact with 

 the machinery of the car. 



The automatic railway-signal, invented by 

 David Rousseau, has been in use for some time 

 on the New York Central road, and has re- 

 cently been adopted by other railroads in this 

 country. The weight of a train when passing 

 a signal-station is made to act upon an electri- 

 cal closing-key placed under one of the rails. 

 By a telegraph-wire and an electro-mechani- 

 cal signal-apparatus the signal at the last sta- 

 tion passed is set at "danger; " and upon pass- 

 ing the next station this is restored to " clear," 

 and the next one moved to " danger." Upon 

 single-track lines the system can be applied to 

 blocking ahead as well as in the rear. 



George Westinghouse, Jr., inventor of the 

 well-known air-brake which bears his name, 

 has recently developed an instrument by which 

 the speed of a railroad-train at any moment is 

 accurately indicated, and also the diminutions 

 and fluctuations of speed, so that, when experi- 

 menting with railroad-brakes, diagrams can be 

 made showing the exact effect of the brake for 

 each instant. The principle of this speed-in- 

 dicator consists in controlling by the action of 

 centrifugal force ;the escape of water under 

 pressure. The higher the rate of speed, the 

 greater the pressure exerted upon an escape- 

 valve by certain revolving weights ; and the 

 greater the pressure upon the valve, the greater 

 the pressure upon the surface of the chamber 

 by the water detained. This pressure is mi- 

 nutely indicated by a. pressure-gauge. This 

 principle is entirely novel in its application, 

 and, although very simple, much study and 

 ingenuity were required to perfect the instru- 

 ment. 



A process of manufacturing car- wheels by 

 twisting a long flat plate of metal about one 

 of its ends upon a mandril, then heating it in 

 a furnace and welding it under pressure, has 

 been patented by Herr Krupp. the Prussian 

 engineer. The skelp is grooved below with a 

 rib above, and is wide at both ends which 

 make the hub and rim of the wheel. The prod- 

 uct, apart from the facility of its manufact- 

 ure, is superior to other sorts of wheels in hav- 

 ing the fibres of the metal arranged in the di- 



