220 SEASONS. [Lesson 



t>ut, on the contrary, it always keeps very nearly 

 in a parallel position, or points always towards 

 the same part of the heavens. 2. The axis of the 

 earth is inclined to the plane of the earth's orbit, 

 which may be conceived by supposing a spindle 

 put 'through a ball, with one end of it touching 

 the ground, oj table; then by moving the ball 

 directly forwards whilst the one end of the ,pindl<e 

 continues to touch the ground, or table, and 

 the other points towards ihe heavens, a tolerable 

 conception of the inclination of the earth's axis to 

 her orbit may be obtained. 



The most easy method of acquiring a right idea 

 of the varieties of the Seasons, and the different 

 lengths of days and nights will be by an experi- 

 ment xwhioh I shall now endeavour >to describe. 

 Let two large circular hoops nearly of q<ual 

 size be procured : let one of these be fixed in an 

 horizontal position, and let the other be fixed 

 within it in such a manner as to cross it in an 

 angle of 23k. degrees, having one half above the 

 horizontal hoop, and the other half below. 

 When night is arrived, the flame of a candle must 

 be fixed -exactly >in the centre of the hoops, and a 

 small terrestrial globe must be taken from its ap- 

 pendages, having a string tied to its north pole, 

 from which string the globe may be suspended. 

 In this experiment, the candle flame must be sup- 

 posed to represent the sun, and the inclined hoop 

 the earth's orbit: just on the inside of this hoop, 

 the globe suspended from the string must be car- 

 tied gently round in a direction from west to east ; 



then 



