BEARINGS OF METEOROLOGY ON AGRICULTURE, ETC. 241 



METEOROLOGY. 



IMPORTANT BEARINGS OF METEOROLOGY ON AGRICUL- 

 TURE AND HYGIENE. 



The recent publications of the French Observatory of Montsotiris (which 

 is under the enterprising directorate of the savant just named) are highly 

 instructive, as indicating some of the new directions in which meteorologists 

 are working; and we will here invite attention more especially to two of 

 these. The labors of Montsouris have elucidated the important bearings of 

 meteorology at once on agriculture and on hygiene. 



The proper object of agricultural meteorology is obviously to deter- 

 mine the influence of the various conditions of climate on vegetation. 

 Everybody knows that heat, light and water are indispensable to a plant; 

 but it is desirable to ascertain and define what part is played by each of 

 these elements individually in the development of each plant, in each of 

 its phases of vegetation, and in the formation of the various organic prin- 

 ciples — starch, sugar, gluten, etc. — -which it furnishes. On this problem the 

 ■observers at Montsouris are busily at work noting the phases of vegetation, 

 making "chemical analyses" of plants, taken j^eriodically, so as to compare 

 the progress of vegetation with the climatic conditions throughout the year, 

 and analj'zing the air and the rain with regard to the products the}^ furnish 

 to vegetation. This last point has excited no little interest lately. jSTitro- 

 gen, of course, forms a large proportion of our atmosphere; but in this free 

 state it does not appear capable of being assimilated by plants. It has to 

 be offered to them in a state of combination, as in manures. Now the air 

 often contains small quantities of natural manures of this character, viz., 

 nitrogen compounds, which are supplied by the air to the ground; such are 

 ammonia, nitrous acid and nitric acid. Whence they come seems still to be 

 doubtful. There is some reason to believe that the ammonia of the air 

 comes from the sea, and the traces of nitric and nitrous acid are said by M. 

 Thenard to arise from electric discharges which traverse the air either in a 

 silent and continuous manner, or in the form of sparks. Then M. Berthe- 

 lot has shown that under the influence of atmospheric electricity the nitro- 

 gen of the air may be fixed directly in organic compounds of the ground, 

 and that this fixation is favored by the development of certain microsco- 

 pic plants. There is evidently here a wide field for scientific research, from 

 which the art of agriculture may be expected to reap great benefit. The 

 rain, too, is an instructive teacher. At Montsouris it is carefully analyzed 

 from time to time, and (as an example of the results) it has been calculated 

 that during the year September, 1875 to September, 1876, a total quantity 



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