52 
AMERICAN PROVINCES—SCIENTIFIC OBSERVATION. 
constituting the United States and the British American prov¬ 
inces had other things to do than to tabulate barometrical and 
thermometrical readings, but there remain some interesting 
physical records from the early days of the colonies,* and there 
is still an immense extent of North American soil where the 
industry and the folly of man have as yet produced little 
appreciable change. Here, too, with the present increased 
facilities for scientific observation, the future effects, direct and 
contingent, of man’s labors, can be measured, and such precau¬ 
tions taken in those rural processes which we call improve¬ 
ments, as to mitigate evils, perhaps, in some degree, insep¬ 
arable from every attempt to control the action of natural 
laws. 
In order to arrive at safe conclusions, we must first obtain 
a more exact knowledge of the topography, and of the present 
superficial and climatic condition of countries where the nat¬ 
ural surface is as yet more or less unbroken. This can only be 
accomplished by accurate surveys, and by a great multiplica¬ 
tion of the points of meteorological registry,f already so 
* The Travels of Dr. Dwight, president of Yale College, which embody 
the results of his personal observations, and of his inquiries among the 
early settlers, in his vacation excursions in the Northern States of the 
American Union, though presenting few instrumental measurements or 
tabulated results, are of value for the powers of observation they exhibit, 
and for the sound common sense with which many natural phenomena, 
such for instance as the formation of the river meadows, called “inter¬ 
vales,” in New England, are explained. They present a true and interest¬ 
ing picture of physical conditions, many of which have long ceased to 
exist in the theatre of his researches, and of which few other records are 
extant. 
t The general law of temperature is that it decreases as we ascend. 
But, in hilly regions, the law is reversed in cold, still weather, the cold air 
descending, by reason of its greater gravity, into the valleys. If there be 
wind enough, however, to produce a disturbance and intermixture of 
higher and lower atmospheric strata, this exception to the general law 
does not take place. These facts have long been familiar to the common 
people of Switzerland and of New England, but their importance has not 
been sufficiently taken into account in the discussion of meteorological 
observations. The descent of the cold air and the rise of the warm affect 
