CHAPTER LVIT. 



THE MAGIC TOP THE GYROSCOPF AND SCIENTIFIC GAMES 



WE will not do our readers the injustice to suppose that they are not 

 familiar with the ordinary top, the delight of all school-boys and young 

 people, of which, therefore, we forbear giving any description ; but we now 

 desire to give some details of the construction of the wonderful magic top. 

 It is composed of a large disc, with an axis turning on two pivots connected 

 with a circle of iron. When in repose, this plaything exhibits nothing of a 

 remarkable character ; it is completely inert, obeying, like all other bodies, 

 the laws of gravity. But when we come to give the disc a movement of 

 rapid rotation, this inert instrument seems to assume a vitality of its own 

 if we attempt to move it ; it resists, and seems to thrust back the hand, and 

 executes movements even in a contrary direction. Besides this, it appears 

 to be freed, in a certain measure, from the laws of gravity ; if we place it 

 on its pivot, instead of falling, as it would when the disc is motionless, it 

 preserves the upright or inclined position in which we place it, the upper 

 extremity of the axis slowly describing a horizontal circle round the fulcrum 

 of the other extremity. 



Few persons are sufficiently familiar with the theory of mechanics to 

 understand these phenomena, and it often happens that such a top purchased 

 to amuse a child becomes an object of wonder and interest to his seniors. 

 W T e do not pretend here to explain mathematically the reason of the facts 

 iDefore us, but the mechanical principle on which this top is constructed is 

 of such great scientific importance, that we will, in a few words, explain it 

 to our readers. It is sufficient to have a little knowledge of mechanics to 

 be aware that a body in motion, subjected to the action of a force tending 

 to give it a directly contrary motion, will follow a movement in a third 

 direction, which is termed the resultant of the two others; and this resultant 

 approaches nearer to one of the original directions, in proportion as the 

 corresponding movement is more rapid in relation to the other. If, for 

 example, you strike a billiard ball, which is rolling past you, in such a 

 manner that you drive it regularly along in the same direction, it appears 

 only to obey a part of the given impulsion, and continues its course in an 

 oblique direction, the speed with which it commenced rolling combining 

 with the impulsion to produce a resultant movement. If it is rolling very 



