EECEEATIVE SCIENCE. 



33 



finite amusement. Your conquest completed, 

 you will find many a sweet little song impro- 

 vised for you, and warbled sotto voce from 

 the windows of their habitation. Mind and 

 listen attentively to it. Approach lovingly, 

 and bend your head forward. Then present 

 one of your fingers. It will be gently pecked 

 at. Next, your lip. That will be welcomed 

 by a "chaste salute." The bird's affection 

 cannot go beyond this. Such a mode of 

 salutation seems to be the only natural way 

 of expressing the deep feelings of an affec- 

 tionate heart. It rules throughout all Nature. 

 Let us honour it, and ever rate it at its real 

 value. Soni soit qui mal y pense ! 



One word more. When you have won 

 your bird's heart, mind and keep possession 

 of it. The heart of a confiding little bird 

 must not be trifled with. It is not like the 

 human heart — pliable and elastic as India- 

 rubber. No ; while one bends, the other 

 breaks. We mortals have the oddest pos- 

 sible ideas about " love." We can love one, 

 twenty, or fifty ! Little birds want only 

 "one" love. In this they live ; in this they 

 die — happy. Surely, if only for variety's 

 sake, it is well to possess — The Key to a 



Bird's Heart (?). 



William Kidd. 



THE GYEOSCOPE. 



"What is a gyroscope?" is a question that 

 many persons have asked, and many more 

 have found some difficulty in answering. 

 To furnish a reply to those who have made 

 the inquiry, and to excite the attention of 

 those to whom the remarkable phenomena 

 exhibited by the gyroscope are unknown, is 

 the object of this paper. 



The instrument in question is the Inven- 

 tion of a French philosopher, M. Poucault, 

 to whom we are indebted for the celebrated 

 demonstration of the earth's axial rota- 

 tion, by means of a pendulum. It consists 



of a wheel, carefully attached to an axis, 

 having the mass of metal composing it dis- 

 posed around its edge, in order that, when it 

 is put into rapid rotation, it may revolve for 

 a longer time than it otherwise would. The 

 axis of this wheel is himg within a ring, 

 which latter is suspended to the end of a 

 semicircular arm, and this, by means of a 

 spindle attached to the middle of its outer 

 edge, is placed on the top of a pillar, rising 

 out of the foot that supports the entire in- 

 strument. 



: The apparatus may, therefore, be de- 

 scribed as consisting of a heavy foot, a, 

 from which rises a hoUow piUar, b, support- 

 ing, by means of the spindle before alluded 

 to, the semicircular arm, c, with its two 

 ends upwards, the spindle being a vertical 

 axis, on which this arm can rotate. The 

 ring, D, is attached to the end of this arm by 

 two pivots, which form a horizontal axis, on 

 which the ring can move ; and through the 

 edge of the ring, at right angles to the pivots 

 by which it is suspended, two screws, e, f, 

 are inserted, and these support the axis of 

 the wheel, a. These arrangements enable 

 the wheel, by means of a cord wound round 

 its axis and quickly drawn off, to have com- 

 municated to it a rapid rotatory motion, the 

 plane of such motion being capable of varia- 

 tion, from the vertical to the horizontal, or 

 any intermediate position, by moving tho 

 ring on the pivots which form its axis; 

 while the spindle attached to the semicir- 

 cular arm, enables the entire system of 

 wheel, ring, and arm to rotate horizontally. 

 ■j The following, among other experimentOi, 

 can be performed with the gyroscope, illus- 

 trating the following principles : — 



That inertia is a property of matter in 

 motion, as well as of matter at rest. 



That the power possessed by Armstrong's 

 and similarly formed guns, of resisting the 

 influence of gravity, is due to the gyratoiy 

 motion given to the ball as it leaves the 

 muzzle of the gun. 



