24 ANNUAL OF SCIENTIFIC DISCOVERY. 



tensive practical experience it is found to answer, the economy which 

 it secures will probably be most advantageously felt in the case of ma- 

 rine engines, the space required for the stowage of fuel in steam-ves- 

 sels being at present so very large. Mr. J. Gooch, of the South- 

 western Railway, has tested Mr. Wright's patent, and the result 

 corresponds exactly with that obtained on Saturday, when 56 pounds 

 of coal evaporated 720 pounds of water in the space of an hour and 

 12 minutes. 



DISK ENGINE. 



. THE improved disk engine which has been fitted up for the purpose 

 of driving the printing presses of the London Times occupies the 

 wonderfully small space of seven feet in length by four in width, and 

 its highest part is but three feet above the floor of the room. The 

 peculiarity of the engine is, that it gives direct motion to a crank on 

 the engine shaft, and exerts a perfectly uniform force on it during the 

 whole revolution. When driven by gearing without a fly-wheel there 

 is no " back lash" in the wheels. The steam can be cut off at a 

 very early part of the stroke without affecting the regularity of the 

 driving force, and although the speed of the piston or the disk rings 

 is but 200 feet per minute, the engine makes three times as many re- 

 volutions in that time as the common engine. It is suggested that this 

 principle could be applied to driving the screw-propeller direct, as it is 

 only necessary that the engine shaft should be extended through the 

 vessel, and have the propeller attached to it. Could this be effected, 

 those vessels which cannot spare much room could advantageously 

 adopt the screw-propeller. 



INVENTION FOR STOPPING STEAM-ENGINES. 



A CORRESPONDENT of a London journal gives an account of his visit 

 to a manufactory in Southgate, where he saw in operation a machine 

 for the almost instantaneous stopping of steam-engines. He says, 

 " We were taken to the end of the spinning-room, when the whole 

 machinery, driven by an engine of 30 horse-power, was in full opera- 

 tion. At a signal, a valve was opened that admitted the atmospheric 

 air, which instantly choked the condenser of the engine, shut off the 

 throttle and water valves, and opened the blow-valves. After this 

 was done, the fly wheel made only one revolution and a quarter, 

 while ordinarily it makes five before it can be brought to a stand. 

 Notwithstanding the suddenness of the stoppage not a single thread 

 was broken. This piece of machinery, which may be called a safety- 

 valve, may be put at any distance, and by means of pipes, it will op- 

 erate in the same manner as if it were close at hand. The value of 

 this must be seen when we consider the frequent cases where persons 

 are caught in the mill-straps and drawn up over the shaft, whereby 

 they are destroyed ; but by this invention the whole machinery may 

 be stopped before they could come in contact with the shaft." The 

 expense of putting up the -apparatus amounts to about three dollars for 

 each horse-power. 



