454 



SCIENTIFIC RECREATIONS. 



Two glass balls, B B', are connected by two. tubes ; one straight and of rather 

 large diameter, the other extremely slender, and winding in and out in a 

 more or less complicated manner. The large tube passes 

 into ball B', and forms a slender point, J, at the orifice of 

 the narrow tube. At the lower end of the ball is a 

 bulb, which is closed with a cork, and contains a 

 coloured liquid. The apparatus is fixed to a board with 

 a ring at each end, by which it can be hung on the wall. 

 When commencing the experiment, it should be hung so 

 that the ball B 7 is uppermost. The liquid then flows through 

 into the ball B, without presenting any particular phenomenon. 

 The apparatus is then turned, and the liquid descends 

 again with great speed, shoots through the opening, J, and 

 rises into the twisted tube. The air displaced from ball 

 B r also rises, however, and mingles with the liquid, and it 

 can be seen circulating through the winding tube in a num- 

 ber of air-bubbles, mingled with drops of liquid, gradually 

 transmitting the pressure of the column contained in the 

 upper ball and straight tube ; so that by means of a similar 

 phenomenon to that of the fountain of Nero, the liquid rises 

 higher than the level of the reservoir, a part falling into 

 ball B, which causes the experiment to be a little prolonged. 

 This circulation of air-bubbles and coloured drops through 

 the twisted tube of the apparatus has a very pretty effect 



THE PNEUMATIC PENCIL. 



This ingenious invention is productive of results 

 Fig. 482. circulating similar to Edison's electric pen. It is the invention of 

 an American gentleman, Mr. J. W. Brickenridge, of 

 Lafayette, Indiana. The illustration (fig. 483) explains the mechanism of 

 the pneumatic pencil. The whole apparatus is figured on the left side 

 of the picture, while the longitudinal section of the pencil is shown 

 on the right, the small cut at the top being a vertical section of a portion 

 of the motive power. Compressed air furnishes the power of pressure, 

 which is accomplished by means of a perforating needle. 



If the treadle is put in motion, a backward and forward movement is 

 imparted to a flexible diaphragm, as in the upper section in the centre of the 

 illustration. By this movement the air is permitted to enter, and is com- 

 pressed by the diaphragm into the flexible tube with which the diaphragm 

 is connected. The air is thus brought into contact with another diaphragm 

 at the end of the tube and presses on it. The pencil is fixed to the latter. 

 When it is desired to use the pencil the apparatus is set in motion, and by 

 a series of sharp, quick perforations, any writing can be traced, as by the 

 electric pen., This indentation can be copied over and over again in a press, 



