C. B. WARRING. 135 



This gives what, for lack of a better name, I may call an 

 abnormal downward impulse, whose action and effect 

 are such as were seen when we flashed off the weight. 



It would be easy to multiply experiments, and to pro- 

 duce some curious results, but if I have succeeded in 

 making clear the principles involved in those already 

 considered, the others will offer no great difficulty. 



For myself, I have found nothing so helpful as to 

 follow the movements of a tee-square falling freely, and 

 to note what it does when rotated quickly — instantly, 

 would be better — from a vertical to a horizontal position, 

 then to a reversal, and again back to its first position. 

 This mode of treatment I have applied from beginning 

 to end of these papers. 



Of course, in a gyroscope there is no break in the con- 

 tinuity of movement. Every section goes gradually 

 from one position to another ; but we may, without detri- 

 ment, consider all the effect as concentrated into certain 

 portions of the time so occupied. 



THE RISING OF THE GYROSCOPE. 



Two familiar principles have sufficed to explain all the 

 phenomena of this instrument thus far. But now we 

 come to another paradoxical movement, and for that 

 shall require a third principle — the law of reaction. 

 Every action is accompanied by an equal and opposite 

 reaction. I push the table, the table pushes me. A 

 man standing on the deck of a boat propels it along by 

 pushing against the immovable bottom of the stream. 

 It is reaction of the fixed rail against the yielding wheel 

 that sends the locomotive along the iron road. 



The gyroscope, under certain conditions, pushes itself 

 up. How it does so, I now shall try to show. 



In all our operations thus far there has been no actual 

 rise of the centre of gravity. But sometimes such a rise 



119 



