AGRICULTURAL METEOROLOGY. 117 
ef the degrees of moisture, heat, &c., which different cultivated pro- 
ductions require under different climates, they will have no difficulty in 
judging of the conditions of new climates. It is thus, also, that the 
network of the War Department will be doubly useful in protecting 
their harvests from atmospheric disturbances, when the normal state of 
the latter shall be known. They will learn exactly the degree of re- 
sistance which they must oppose to these disturbances. By-and-by, 
when the vital perturbations shall be better ascertained, we shall be 
able to predict atmospheric disturbances, and vice versa. By the delay 
or advance of different physiological functions of the plant—for example, 
of the leafing, or spring-flowering, or, further, of the leaf-fall in antumn— 
it will be easy to predict whether winters will be vigorous or mild. 
Already, in Europe, when the dandelion (Leontodon taraxacum) expands 
its golden flowers, we are sure that the cold will return no more. So it 
is that in the vital, and even in the moral state, everything being in- 
timately connected, the sciences aid each other mutually. We conceive 
now why the meteorological observations for any application to agricul- 
ture can be made only by agriculturists, or by observers especially in 
charge of this study. I therefore appeal to farmers to take these facts 
into immediate consideration, for it is already time to begin, and, as 
one man, undertake the task in the interest, particular and general, of 
agricultural science. | 
We conceive now how, by a judicious combination of the indications 
that are furnished by the meteoro-telegraphic observations, combined 
with the knowledge of atmospheric influences on plants, which follow 
from the first two propositions, the farmers will obtain an almost in- 
credible degree of certitude in all their agricultural operations. 
3. An experimental field should be established in the Department of 
Agriculture, where all the physical and chemical agents of the soil and 
atmosphere, which exert any influence on vegetation, could be submitted 
to profound study and repeated experiments, with the view of discover- 
ing the laws regulating vegetable organization. 
There still remain a considerable number of questions to resolve and 
verify concerning the action of different physical agents on a plant; or, 
more properly speaking, concerning the intimate relation which exists 
between its physical functions and its agricultural productions. If we 
consider, for example, the temperature, we are ignorant whether the 
progress of vegetation isin relation to the simple arithmetical sum of the 
thermometrical degrees, as Reaumur and others think; or, as Quetelet 
proposes, to the square of the degrees; or, again, as Babinet supposes, 
to the square root. If we examine light, the question is not yet settled 
_ as to the different actions which the luminous, calorific, and chemical 
rays exercise upon germination, upon the decomposition of carbonic 
acid from the leaves, the fixation of carbon, the formation of chlorophyl, 
&e. In electricity we are still more ignorant as to its pernicious or 
favorable influence on plants, whether static or dynamic. All these 
undetermined questions, and many others, were pointed out in my first 
report, and the same ignorance exists as to the cause and action of 
frost. No wonder that the distinguished horticulturist, Professor Lind- 
ley, should conclude, after forty years of experience, “that the fatal 
effect of frost upon plants is a more complicated action than has been 
supposed;” and,the only conclusion he’ has arrived at is, ‘that the 
power of plants to resist frost is the consequence of specific vitality,” of 
which he knows nothing more. Now, all these important questions, 
and many cthers which spring up daily in the course ot investigation, 
should be submitted to a new test in the proposed experimental field, 
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