Curiosities of Science. 1 1 



ALL THE WOELD IN MOTION. 



HUMBOLDT, in his Cosmos* gives the following beautiful illus- 

 trative proofs of this phenomenon : 



If, for a moment, we imagine the acuteness of our senses preterna- 

 turally heightened to the extreme limits of telescopic vision, and bring 

 together events separated by wide intervals of time, the apparent re- 

 pose which reigns in space will suddenly vanish ; countless stars will be 

 seen moving in groups in various directions ; nebulae wandering, con- 

 densing, and dissolving like cosmical clouds ; the milky way breaking 

 up in parts, and its veil rent asunder. In every point of the celestial 

 vault we shall recognise the dominion of progressive movement, as on 

 the surface of the earth where vegetation is constantly putting forth its 

 leaves and buds, and unfolding its blossoms. The celebrated Spanish 

 botanist, Cavanilles, first conceived the possibility of " seeing grass 

 grow," by placing the horizontal micrometer wire of a telescope, with a 

 high magnifying power, at one time on the point of a bamboo shoot, and 

 at another on the rapidly unfolding flowering stem of an American aloe ; 

 preciselv as the astronomer places the cross of wires on a culminating 

 star. Throughout the whole life of physical nature in the organic as 

 in the sidereal world existence, preservation, production, and develop- 

 ment, are alike associated with motion as their essential condition. 



THE AXIS OF ROTATION. 



It is remarkable as a mechanical fact, that nothing is so per- 

 manent in nature as the Axis of Rotation of any thing which is 

 rapidly whirled. We have examples of this in every-day prac- 

 tice. The first is the motion of a boy's hoop. What keeps the 

 hoop from falling ? It is its rotation, which is one of the most 

 complicated subjects in mechanics. 



Another thing pertinent to this question is, the motion of a 

 quoit. Every body who ever threw a quoit knows that to make 

 it preserve its position as it goes through the air, it is necessary 

 to give it a whirling motion. It will be seen that while whirl- 

 ing, it preserves its plane, whatever the position of the plane 

 may be, and however it may be inclined to the direction in 

 which the quoit travels. Now, this has greater analogy with 

 the motion of the earth than any thing else. 



Another illustration is the motion of a spinning top. The 

 greatest mathematician of the last century, the celebrated 

 Euler, has written a whole book on the motion of a top, and 

 his Latin treatise De motu Turbinis is one of the most remark- 

 able books on mechanics. The motion of a top is a matter of 



* Bolm's edition. 



