Popular Science Montldy 



545 



of the great Jutland Battle has been fought 

 out on this game-board. 



On the board the home fleet is shown by 

 light-colored ships, and the enemy's by 

 dark-colored ones. When the game begins 

 on the board the scouts are shown in contact. 

 Behind their screen the supporting ships close 

 up, and behind them the big battleships 

 maneuver for the opening of fire action. 



The war game as practiced now by all 

 armies and navies w^as first devised by 

 Von Moltke, who, when elevated to the 

 post of Chief of Staff in 1857, introduced 

 it into the German army. The United 

 States army works out its problems on 

 maps scaled twelve inches to the mile, at 

 the Leavenworth Army School of the Line. 

 The Coast Artillery has its own game, in 

 which the advance of a hostile fleet is 

 opposed by mines and gun fire. The 

 artillerists are taught to identify at a 

 glance every type of foreign vessel. 



AIR DRAWN TO INTAKE 

 MANIFOLD BY MOTOR, 

 CAUSING VACUUM IN 

 BRAKE CYLINDER. 

 UWYE OPEN, BRAKES, 

 ON. 



Stopping the Automobile with a 

 Vacuum Brake 



AXEW brake has been invented for 

 automobiles — a vacuum brake, which, 

 as its name implies, operates not by the 

 force of compressed air but by means 

 of a vacuum created by the engine, operating rod. 

 The mechanism of the new device 

 consists of a cylinder containing a 

 piston faced with leather, a lever 

 that connects with the brake rod, a 

 small controlling valve 

 and sufficient copper 

 tubing to connect the 

 intake manifold with 

 the valve and the 

 vacuum cylinder. 



When the engine is in 

 operation a vacuum is 

 created within the in- 

 take manifold which 

 amounts to a suction of 

 about ten pounds to the 

 square inch. This suction 

 is employed to move for- 

 ward the piston in the 

 cylinder. By leverage this 

 suction pull may be de- 

 veloped to a thousand 

 pounds pressure at the rear 

 wheels. The pressure of a 

 finger on a lever at the steer- 

 ing post is sufficient to apply 

 this tremendous force to the 

 brakes. 



The vacuum brake with its thousand 

 pounds pressure serves to counteract any 

 inequality of brake adjustment. Thus if 

 one brake requires three hundred pounds 

 pressure to make it effective, while the other 

 responds to not less than five hundred 

 pounds pressure, it will be evident that one 

 thousand pounds applied between them will 

 be ample for both. This makes brake 

 operation more certain and is an important 

 safety factor. 



The engine must be running in order to 

 make the vacuum brake operative, but the 

 ver>^ slowest movement of the motor is 

 sufficient to get results. Even with the 

 gear lever in neutral and the engine at rest, 

 the application of the electric starter is 

 sufficient, or the cranking of the engine by 

 hand will accomplish the same result. A 

 slight leak in the copper tubing will not 

 interfere with the action of the vacuum 

 brake. 



W'hile acting as a service brake, this new 

 "self-starter" is not designed to replace the 

 hand or emergency brake which holds the 

 car on a grade while the engine is idle. The 

 cylinder is only four inches long and has a 

 diameter of seven and three-eighths inches. 

 It is braced in position by attaching it to 

 cross members of the frame. 

 The controlling valve may be 

 attached to the lower part of the 

 dash or the engine base. 



When the engine is in operation a vacuum is created within 

 the intake manifold which amounts to a suction pull of ten 

 pounds to the square inch. This is magnified by leverage 



