10 



as night approaches and the surface of the earth begins to cool, 

 the air in contact with it begins to cool also, and, like the current 

 on the mountain top, to give up a portion of its watery burden. 

 This water descends in particles infinitely minute, which collect 

 on every leaf and hang on every blade of grass in drops of glit- 

 tering dew. " Mark here," says Professor Johnston, to whom I 

 am indebted for the material of this illustration, " a beautiful 

 adaptation. Different substances are endowed with the property 

 of radiating their heat, and of thus becoming cool with different 

 degrees of rapidity, and those substances which in the air become 

 cool first, also attract first and most abundantly the particles of 

 falling dew. Thus in the cool of the evening the grass plot is 

 wet while the gravel walk is dry, and the thirsty pasture and 

 every green leaf are drinking in the descending moisture, while 

 the naked land and the barren highway are still unconscious of 

 its fall." 



I shall have occasion, in a moment, to observe how the practice 

 of deep and subsoil ploughing proceeds upon and takes for granted 

 this agency of water in the production and growth of vegetable 

 life. 



To subdue the earth and to replenish it ; in this first command- 

 ment lies the epitome of our art. 



To subdue the earth and to replenish it is to fit it for the abode 

 of cultivated, developed man. 



In redeeming the bog meadow of which I spoke, what has the 

 farmer accomplished ? If prudently done, at times of relief from 

 other work, he has added greatly to the value of his estate. He 

 has given beauty, softness and finish to the landscape. Every 

 traveller that passes that way has cause to bless him. He has 

 sweetened the air, made his own and his neighbor's abode 

 healthier, and given a ruddier tint to the rose upon his daughter's 

 cheek. He has increased the capacity of the earth for the very 

 end for which it was made. That portion which was before 

 worse than useless, now affords means of sustenance and support 

 for a human beini];. 



Look at the same thing on a larger scale. In 1780 the island 

 of Great Britain contained about nine millions of inhabitants. 

 In seventy years the population doubled, and the quantity of food 



