EXPERIMENTS ON CENTRIFUGAL FORCE. 135 



ibstance, which have the same size as the holes, are 

 placed in the holes, and the apparatus is worked at first 

 slowly, afterwards more and more rapidly. Even a 

 moderate speed is sufficient to start the bullets in the two 

 most distant holes. If they are both of equal size, 

 and the distance of the two holes from the centre of 

 the plate, and their . width, is precisely equal, they 

 are thrown out at the same instant. When the speed 

 increases, the next two bullets will roll off, and when 

 the velocity of rotation becomes still greater the two 

 nearest to the centre will fly off the plate. It requires, 

 obviously, the same force to start each bullet from its 

 place. Hence, when the two first bullets fly off, while 

 those nearer to the centre are still in their place, we 

 may conclude that, other circumstances being equal, the 

 centrifugal force is greater the greater the distance of 

 the rotating body from the centre of its path. Observ- 

 ing further that increased speed starts the bullets nearer 

 to the centre, it proves that the centrifugal force be- 

 comes greater the greater the velocity of rotation, or the 

 shorter the time required by the body for completing 

 a revolution. 



The disc is made of pasteboard, from 2 to 4 thick, with a radius 



i of 10 or ll cm ; a hole in the middle, 6 mm wide, allows the fixing 



i screw just to pass through the disc. The six holes for the bullets, all 



of the same width, are placed along a diameter, so that there are three 



( holes on each side of the centre, A cork- borer may be used for 



piercing the holes,but it will become very blunt by the operation ; it is 



better to use a kind of short hollow punch, expressly made for the 



purpose. Pasteboard which is not quite flat must be made moderately 



moist and pressed between two boards until it is dry again, 



A frame may be screwed upon the plate, of which fig. 

 98 shows the lower part : the whole frame is repre- 



