14 THE BALANCE OF FORCES. 



gyroscope, we can determine, as with the pendulum, the 

 motion of the earth around its axis ; and we learn why, 

 during its movement around the sun, its axis is tmde- 

 viatingly pointed towards one point in space, marked in 

 our Heavens as the Polar Star. 



In addition to these great rotations, the earth is sub- 

 jected to other motions, as the precession of the equi- 

 noxes and the nutation of its axis. Rocking regularly 

 upon a point round which it rapidly revolves, whilst it 

 progresses onward in its orbit, like some huge top in 

 tremulous gyration upon the deck of a vast aerial ship 

 gliding rapidly through space, is the earth performing 

 its part in the great law of motion. 



The rapidity of these impulses, supposing the powers 

 of the physical forces were for a moment suspended, 

 would be sufficient to scatter the mass of our planet 

 over space as a mere star-dust. 



Limiting, as much as possible, the view which opens 

 upon the mind as we contemplate the adjustments by 

 which this great machine, our system, is preserved in all 

 its order and beauty, let us forget the great movement 

 of the whole through space, and endeavour to consider 

 the effect of those motions which are directly related to 

 the earth, as a member of one small group of worlds. 



We cannot for a moment doubt, although we have not 

 any experimental proof of the fact, that the proper 

 motions of the earth materially influence the conditions 

 cf the matter of which it is formed. Every pair of 

 atoms is, like a balance, delicately suspended, under 

 the constant struggle which arises from the tendency to 

 fly asunder, induced by one order of forces centrifugal 

 force and the efforts of others, gravitation and cohe- 

 sion, to chain them together. The spring is brought to 

 the highest state of tension one tremor more, and it 

 would be destroyed. 



We cannot, by any comparison with the labours of 

 the most skilful human artisan, convey an idea of the 



