APPLIED MECHANICS LECORNU. 281 



that, in case of need, it may be driven with steam coming direct 

 from the boiler. The su])ply is automatically received in case of a 

 deficiency from the accumulator. At Middlesljorough (England) 

 the installation of two low-pressure turbines allowed the ])atting 

 out of service of 28 furnaces, thus saving 120 tons of coal per day. 



VI. MISCELLANEOUS MATTERS. 



In the Keview for 1909 I noted a device for diminishing the rolling 

 of ships, based upon the lateral displacement of a heavy mass in a 

 viscous fluid. The stability producer of Frahm depends upon a 

 similar principle. Two reservoirs of water are placed symmetrically 

 upon the opposite sides of a ship and communicate by a tube which 

 can be closed at will. This opening is controlled, according to the 

 oscillation period of the water passing alternately from one reservoir 

 to the other, so as to control the oscillations of the ship itself. Experi- 

 ments made at Hamburg showed that the rolling could be reduced 

 from 11° to 2.5°. I may add that smce 1883, Sir Watts tried the 

 same device upon the gunboat Injlexihle, and in France, in 1885, 

 Bertin proposed it for the cruiser Jeanne-d'Arc. 



In the Review for 1909, some mention was made of speed gears 

 which have the purpose of varying at will or reversing the speed of 

 rotation of a shaft driven by another shaft which must run at constant 

 speed and in a constant direction. Since then a new and very inter- 

 esting solution has been made by Williams and Janney. The trans- 

 mission of the power is hydraulic. The driving shaft carries a crown 

 of cylinders whose axes are parallel with that of the shaft and each 

 contains a piston jointed to a rod. The end of each piston rod is in 

 turn jointed to a point of a ring which can oscillate about an axis at 

 right angles to the shaft of the motor. Further, this ring incloses a 

 concentric j)late which does not partake of tiie movement of the 

 shaft but may be fixed iu a poi^ition more or less inclined to that of 

 the shaft. It is apparent, then, that according to the inclination 

 given to the i)late the travel of the ])iston rods will be more or less 

 great; it is zero when the ])late is jjer])endicular to the shaft. The 

 movement of the pistons is used for j)umping oil, and it is evident 

 that the quantity pumped at each turn of the shaft de])ends on the 

 position of the plate. Further, the driven shaft is provided with 

 similar devices except that its jilate is rigidly fixed. The whole is 

 assembled and inclosed in a tight box. Its method of working is as 

 follows: The oil punij^ed during the rotation of the driving shaft is 

 sent to the cylinders of the driven shaft, causing their pistons to work. 

 The displacement of these pistons causes the rotation of the driven 

 shaft and its velocity of rotation is ])ro]3ortional to the volume of air 

 l)umped in a unit of time; this volume is varied by inclining more or 

 less the i)late of the driving shaft. 



