22 THE ATMOSPHERE AND THE FORCES IN IT. 



A child properly managed, and left to spend a good 

 many hours every day in sunshine, has more color, more 

 strength, more activity, more health, and better spirits, 

 in consequence. A child kept away from the sunlight is 

 pale, weak, dull, delicate, and sad, and is liable, when 

 this exclusion from the sun s light is long continued, to 

 many forms of fearful disease. 



71. The sun, and, with it, the air, are constantly acting, 

 with great power, upon the soil. 



The heat of the sun swells or expands the particles, 

 and thus makes room for the entrance of the air ; and the 

 oxygen of the air and the other gases which float in the 

 air combine with some of the elements of the soil, and 

 render them fit to aid in the growth of plants. Other 

 beneficial effects are produced, of which more will be 

 said hereafter. All these are increased by the frequent 

 stirring of the soil. 



Hence it is that when trees are to be planted, it is 

 important to dig the holes some time beforehand, in order 

 that the fresh earth in the holes may be acted upon by 

 the sun and the air as long as possible. 



72. The atmosphere produces many other different 

 effects upon animals, upon plants, and upon the soil, 

 varying with the direction and force of the winds, heat 

 and cold, the weight and the moisture of the air, rains 

 and droughts, dews, clouds, and fogs, mists and storms. 



73. What is Electricity? We know it only by its 

 effects. If we rub a rod of amber, or scaling wax, with 

 a piece of woollen cloth, the amber or wax is immediately 

 excited, and draws towards itself, or attracts, light bodies, 

 such as bits of thread, or of elder-pith hung to a thread. 

 The cause of this attraction was called electricity, from 



