L. MECHANICS AND ENGINEERING. 439 



operating without any increase of pressure upon pump or 

 hose line, the valve largely increases the efficiency of the en- 

 gine to which it is attached. 



SELF-WATEEING LOCOMOTIVES. 



One of the most practical improvements which is coming 

 into very extensive use in this country is the self-supplying 

 water-apparatus for locomotives. As the following descrip- 

 tion will show, the devices employed are at once simple and 

 efficient : A water-trouo:h from eis^ht hundred to twelve hun- 

 dred feet long is laid between the tracks of the railway, and 

 as the engine passes along at a velocity of, say, twenty miles an 

 hour over the trough, the fireman, by means of a lever, lowers 

 one end of a pipe, and the water is scooped up, as it were, into 

 the tender. In winter the water in the trough is prevented 

 from freezing by means of steam-pipes. The convenience of 

 this device is not its only meritorious feature, for, in addition 

 to this, it saves considerable time in stoppages at watering- 

 stations, thus permitting a more moderate rate of speed to 

 be maintained a practice which realizes material economy in 

 the running of trains. Z>, XXXII., 245. 



STATIONARY HYDRAULIC ENGINE FOR RAILWAYvS. 



The application of the hydraulic power to the movement 

 of a system of belts or bands in working stationary railroads, 

 especially in mines, forms the subject of a memoir, by Caval- 

 lero, lately communicated to the Academy of Sciences of Tu- 

 rin, in which he specially discusses the methods invented by 

 Aguido, and applied by him to several roads in Italy. The 

 theoretical investigation of Cavallero is supplemented by a 

 numerical application to the apparatus established on the in- 

 clined plane at Lauslebourg. Atti della Ji. Acad, della Sci- 

 enza. Twin., 1 8 7 5, L., 577. 



ELECTRO-CAPILLARY MOTOR. 



A curious little engine, termed an electro-capillary motor, 

 has been described by M. Lippmann. If a globule of mer- 

 cury be placed in a saucer, together with a little solution of 

 potassium dichromate, acidified with sulphuric acid, and it 

 be touched upon the side Avith a point of iron, it will at once 

 contract laterally, drawing itself away from the iron. This 



