I thank you, Sir, for your pamphlet on the climate of the West, and have read it with great satisfaction. altho’ it does not yet establish a satisfactory theory, it is an additional step towards it. mine was perhaps the first attempt, not to form a theory, but to bring together the few facts then known and suggest them to public attention. they were written between 40. & 50. years ago, before the close of the revolutionary war, when the Western country was a wilderness untrodden but by the foot of the savage or the hunter. it is now flourishing in population and science, and after a few years more of observation & collection of facts they will doubtless furnish a theory of solid foundation. years are requisite for this, steady attention to the thermometer, to the plants growing there, the times of their leafing & flowering it’s animal inhabitants, beasts, birds, reptiles & insects, it’s prevalent winds, quantities of rain and snow, temperature of fountains and other indexes of climate. we want this indeed for all the states, and the work should be repeated once or twice in a century to shew the effect of clearing and culture towards changes of climate. my Notes give a very imperfect idea of what our climate was, half a century ago, at this place, which being nearly central to the state may be taken for it’s medium. latterly after seven years of close & exact observations I have prepared an estimate of what it is now, which may some day be added to the former work; and I hope something like this is doing in the other states, which, when all shall be brought together, may produce theories meriting confidence. I trust that yourself will not be inattentive to this service, and that to that of the present epoch you may be able to add a second at the distance of another half century. with this wish accept the assurance of my respectful consideration.

Th: Jefferson