SECRETARY'S REPORT. 159 



III. — Meteorology. 



The science of meteorology is closely allied to agriciiltnre, relat- 

 ing, as it does, to those forces in nature which contribute to the 

 growth and perfection of the vegetable productions of the earth. 

 Light, heat, atmospheric air, electricity, rain, snow, frost and dew, 

 each have an influence upon the growth of all cultivated plants. 

 Therefore, an acquaintance with the laws of nature by which these 

 agencies are controlled, furnishes a direct aid to the husbandman, and 

 no study is more useful or interesting. Dr. Reynolds, in his able 

 report on the agriculture of Middlesex county, before alluded to, 

 makes the following remarks in his introduction to that branch of 

 tlie subject now under consideration : 



"As all plants are made up chiefly of elements previously exist- 

 ing in the atmosphere, its composition and the changes which 

 occur among its elements, cannot fail to be an interesting and 

 important study. The atmosphere is composed of nitrogen, Qxy- 

 gen, water in the form of vapor, carbonic acid, and a minute 

 amount of aflamonia, and nitric acid. When a plant is exposed to 

 the free action of the atmosphere and the rays of the sun, it is 

 found to increase in size and weight. This increase is owing to 

 the carbon which the plant receives from the atmosphere. Carbon, 

 in the form of carbonic acid, or carbon united with oxygen, is 

 absorbed by the leaves and green coverings of the growing 

 branches, and in their vessels is decomposed by the power of the 

 sun's rays. The carbon is appropriated to its own use by the 

 plant, and the oxygen is thrown ofi' into the atmosphere. The 

 rays of the sun produce at least three distinct effects, or communi- 

 cate three distinct impulses, viz : the lighting, the heating, and the 

 chemical impulse. It is the latter impulse that causes the decom- 

 position of the carbonic acid in the vessels of plants. But in 

 order that this impulse may produce its full eflect, the heating 

 impulse must be present also ; and to render the plant capable of 

 being acted upon, moisture must be contained in the air. By a 

 proper understanding of these facts, we are able to produce an 

 artificial climate that may enable us to repeat in a northern zone 

 the growths of the tropics." 



The soil and climate of a country have considerable influence 

 upon its agricultural capacities, and there are also several other 



