EXPERIMENTS ON CENTRE OF GRAVITY. 



2 9 



from its balance. The vertical line of the centre of gravity passes through 

 the point of support, and the forks oscillate with the cork, which serves as 

 their support, thus forming a movable structure, but much more stable than 

 one is inclined to suppose. This curious experiment is often performed by 

 conjurors, who inform their audience that they will undertake to empty the 

 bottle without disturbing the cork. If a woodcock has been served for 

 dinner, or any other bird with a long beak, take off the head at the extreme 

 end of the neck ; then split a cork so that you can insert into it the neck of 

 the bird, which must be tightly clipped to keep it in place ; two forks are 

 then fixed into the cork, exactly as in the preceding example, and into the 



Fig. 22. Another experiment on the same subject. 



bottom of the cork a pin is inserted. This little contrivance is next placed 

 on a piece of money, which has been put on the opening of the neck of the 

 bottle, and when it is fairly balanced, we give it a rotatory movement, by 

 pushing one of the forks as rapidly as we please, but as much as possible 

 without any jerk (fig. 22). We then see the two forks, and the cork 

 surmounted by the woodcock's head, turning on the slender pivot of a pin. 

 Nothing can be more comical than to witness the long beak of the bird 

 turning round and round, successively facing all the company assembled 

 round the table, sometimes with a little oscillation, which gives it an almost 

 lifelike appearance. This rotatory movement will last some time, and wagers 

 are often laid as to which of the company the beak will point at when it 



