in this first great canvass which you have sketched.  In no case, perhaps, does habit attach our choice or judgment more than in climate.  The Canadian glows with delight in his sleigh and snow, the very idea of which gives me the shivers.  The comparison of climate between Europe and North America, taking together its corresponding parts, hangs chiefly on three great points. 1.  The changes between heat and cold in America are greater and more frequent, and the extremes comprehend a greater scale on the thermometer in America than in Europe.  Habit, however, prevents these from affecting us more than the smaller changes of Europe affect the European.  But he is greatly affected by ours. 2.  Our sky is always clear; that of Europe always cloudy.  Hence a greater accumulation of heat here than there, in the same parallel. 3.  The changes between wet and dry are much more frequent and sudden in Europe than in America.  Though we have double the rain, it falls in half the time.  Taking all these together, I prefer much the climate of the United States to that of Europe.  I think it a more cheerful one.  It is our cloudless sky which has eradicated from our constitutions all disposition to hang ourselves, which we might otherwise have inherited from our English ancestors.  During a residence of between six and seven years in Paris, I never but once saw the sun shine through a whole day, without being obscured by a cloud in any part of it:  and I never saw the moment, in which, viewing the sky through its whole hemisphere, I could say there was not the smallest speck of a cloud in it.  I arrived at Monticello, on my return from France, in January, and during only two months’ stay there, I observed to my daughters, who had been with me to France, that twenty odd times within that term, there was not a speck of a cloud in the whole hemisphere.  Still I do not wonder that an European should prefer his grey to our azure sky.  Habit decides our taste in this, as in most other cases.

The account you give of the yellow fever, is entirely agreeable to what we then knew of it.  Further experience has developed more and more its peculiar character.  Facts appear to have established, that it is originated here by a local atmosphere, which is never generated but in the lower, closer, and dirtier parts of our large cities, in the neighborhood of the water; and that, to catch the disease, you must enter the local atmosphere.  Persons having taken the disease in the infected quarter, and going into the country, are nursed and buried by their friends, without an example of communicating it.  A vessel going from the infected quarter, and carrying its atmosphere in its hold into another State, has given the disease to every person who there entered her.  These have died in the arms of their families, without a single communication of the disease.  It is certainly, therefore, an epidemic, not a contagious disease; and calls on the chemists for some mode of purifying the vessel by a decomposition of its atmosphere,