566 SCIENCE PROGRESS 



to the right is a movement in a direction at right angles to the 

 tendency, and the far end rises. There are two directions at 

 right angles to this tendenc}", one upward and one downward. 

 It is puzzling sometimes to know which right angle will be 

 followed. In the present case it is easy to tell by reference to 

 the known movement of a top. Consider the axis of the spool 

 to be the axis of the top and the far end to be the support of 

 the top, or point on which it is spinning in an anti-clockwise 

 direction, the direction of gravity being supposed for the 

 moment aw^ay from 3'ou. The action of the string tending to 

 turn the far end to the right or the near end to the left corre- 

 sponds to the action of gravity on the top when it is leaning to 

 the left, tending to make it fall more to the left. It does not do 

 so, but moves sideways in the direction of the spin, i.e. actually 

 towards the earth ; or, in other words, the other end, or far end, 

 is raised. If the spin is left-handed of course the result is 

 reversed, and so it is a pity when learning and acquiring the 

 habit to base it upon a consideration which must be reversed 

 when the direction of spin is reversed. The better instruction 

 to follow is to jerk the business hand toward the high side — 

 it being understood, of course, that the business hand is the one 

 w^hich, by its upward jerk, imparts the spin. With such a rule 

 as the early guide the instinct, which is quicker than the recol- 

 lection and application of any rule, is from the first directed 

 aright, and no conscious effort of reversal is needed whether the 

 direction of spin is right or left handed or the near or the far 

 end is falling. 



In order not to be tied to the crab-like method of pla3'ing 

 sideways, which is so often seen, it is well to practise pla^'ing 

 with a right or left spin indifferently. If playing alone, the 

 change may be brought about b^^ moving round to the side of 

 the spool which is moving upwards and catching the spool on 

 the stick held by the passive hand, then in running the spool 

 down on to the string it will be found to be reversed in direction 

 as seen b}?- the player, but not as regards the points of the 

 compass. This catching on the passive stick is more easily 

 effected, at first, at any rate, by catching on the active stick 

 first and then catching it on the passive stick. The direction 

 of spin may also be reversed by throwing the spool up and 

 turning half round before catching it on the string. Quite a 

 moderate amount of practice, reversing ever}- time b}' one or 



