find that the four positions of the earth referred to ah'eady, are 

 evidently important ones. If the shape of the orbit is constant, 

 if the locahties of these positions are permanent and taken up at 

 exactly the same time every year, —then the climatic conditions are 

 unchangeable too. One other point however has to be borne in 

 mind, viz., the position of the earth's axis. The axis does not 

 stand upright as we might say, if it did there would be no seasons. 

 At present it is inclined to the plane of the orbit at an angle of 

 about 23f degrees, and it is the inclination of the north pole iu the 

 direction of the sun that brings on our SLUiimer, this, as already 

 stated, being the case while the ear*-h is at its greater distance 

 from the sun, and travelling round the larger curve ot its orbit. If 

 this position of the axis is invariable, then along with the other 

 conditions mentio'icd, we shall have a general permanency of 

 climate. But the very title of our subject impUes great change of 

 climate, and here we enter upon its explanation. Though there 

 is stability in the Solar System as a whole, there is everlasting 

 change going on among the units that compose it. Rest, there is 

 none in the whole Universe of God. The physicist tells tells us 

 that in every block of the finest steel, each invisible particle or 

 molecule is in constant movement with a rapidity ultra-micro- 

 scopic and altogether inconceivable, yet no molecule escapes, and 

 the mass of granite and the block of steel preserve their size, 

 shape and weight. So the astronomer also teaches us, that suu 

 and plant and satellite, meteor and asteroid, are in movement of 

 inconceivable swiftness ; the sun with all its attendants rushing 

 forward through space, whence and whither no one can tell; each 

 planet meanwhile whirling round the sun, not in the smooth linear 

 orbit we draw in our diagrams, but sometimes outside it, sometimes 

 inside, yet always keeping true to its main direction ; rotating on 

 its axis, the axis like itself never preserving exactly the same 

 direction ; the orbit of the planet, like an elastic ring expanding 

 and contracting — now elliptical and now nearly circular, but always 

 restrained within certain defined limits ; the equinoxes to which we 

 have referred never occurring in the same spot, but they and the 

 perihelion travelling round in opposite ways ; thus as it has been 

 eloquently said, " mutation and change are everywhere found; all 

 is in motion, orbits expanding or contracting, their planes rocking 

 up or down, their perihelia and nodes sweeping round the sun in 

 opposite directions, but the limits of all these changes are fixed ; 

 these limits can never be passed, and at the end of a vast period, 

 amounting to many millions of years, the entire range of fluctuation 

 will have been accomplished, the entire system, planets, orbits, 

 inclinations and nodes will have regained their original values and 

 places, and the great bell of eternity will have then sounded One." 



