C. B. WARRING. 195 



On causing the latter to rotate with very moderate 

 speed about the axis X, the end A will rise to a vertical. 

 There is neither mystery nor paradox about it. But, 

 first, I will explain my diagram. It represents two 

 "gyrostats" (or rather the same one in two positions). 

 M and n are standards, five or six inches high, to sup- 

 port the instruments. They rest on the turn-table. 

 The ring is the ring of my gyroscope. The dotted lines 

 are merely to show the case which, to make a gyrostat, 

 is placed, instead of the ring, around the wheel. 



The rationale is easily made out. Suppose our tee- 

 square to be held horizontally, the leg coinciding with 

 the part of the axis extending towards A, and the two 

 arms to be a section through the centre of the wheel. As 

 the table turns in the direction of the large arrow, the 

 wheel turning in the direction of the little elliptical ar- 

 rows, the arm towards m will move to the left of its 

 present position (the direction is indicated by the small 

 straight arrows). While this arm of our tee (or section) 

 is going down to a vertical it retains that motion, and 

 therefore still moves towards the left. For a like 

 reason the other arm of our tee (now comes to the top) 

 moves to the right ; hence, the end, A, of the axle is 

 moved upwards, and, as this process continues, the axle 

 soon becomes vertical. If the centre of our turn-table 

 could be placed at the north pole the axle would become 

 parallel to the axis of the earth. 



If the gyroscope were carried from the pole (supposing 

 that we now have for our purpose that impossible thing, 

 a perfect instrument) its axis will remain parallel to the 

 earth's. Hence, as it goes south, it will show less and 

 less elevation, until, at the equator, the axle will be 

 horizontal. Still going south, the other end will begin 

 to go down, until, at the south pole, the axle will again 

 be vertical. 



Place the gyroscope so that the axle points east and 



179 



