236 POPULAR LECTURES AND ADDRESSES. 



The experiment thus described by Guiot of 

 Provence is familiar to the present generation, being 

 taught by Peter Parley, The Boy's Own Book, 

 and other eminent scientific instructors of the 

 young : and any reader of Good Words, having 

 access to a little bar magnet such as that used for 

 attracting magnetic swans, may make it for himself. 

 Guiot says " this is an art that cannot deceive," but 

 I doubt whether any one repeating the experiment 

 carefully will agree with him. The mode of 

 support is not satisfactory. Water in an open 

 basin scarcely ever has its surface free enough from 

 dust or other impurities to allow a straw floating 

 on it to turn with perfect freedom ; and it will be 

 found that the needle will sometimes stick in 

 positions sensibly inclined to one definite line 

 towards which it tends, or at best that it will come 

 very sluggishly into its proper position. A pretty 

 and instructive experiment may, however, be made 

 by deviating a little from the ordinary way of 

 floating the needle. Instead of placing it length- 

 wise on a straw, stick it transversely through one 

 end of a small round wooden bar. The smooth 



