The flats bordering upon the Genesee River are amongst the richest lands that are to be met with in North America, to the east of the Ohio. Wheat, as I told you in a former letter, will not grow upon them; and it is not found that the soil is impoverished by the successive crops of Indian corn and hemp that are raised upon them year after year. The great fertility of these flats is to be ascribed to the regular annual overflowing of the Genesee River, whose waters are extremely muddy, and leave no small quantity of slime behind them before they return to their natural channel. That river empties itself into Lake Ontario: it is somewhat more than one hundred miles in length, but only navigable for the last forty miles of its course, except at the time of the inundations; and even then the navigation is not uninterrupted the whole way down to the lake, there being three considerable falls in the river about ten miles above its mouth: the greatest of these falls is said to be ninety feet in perpendicular height. The high lands in the neighbourhood of the Genesee River are stony, and are not distinguished for their fertility, but the valleys are all extremely fruitful, and abound with rich timber. The summers in this part of the country are by no means so hot as towards the Atlantic, and the winters are moderate; it is seldom, indeed, that the snow lies on the ground much longer than six or seven weeks; but notwithstanding this circumstance, and that the face of the country is so much diversified with rising grounds, yet the whole of it is dreadfully unhealthy; scarcely a family escapes the baneful effects of the fevers that rage here during the autumn season. I was informed by the inhabitants, that much fewer persons had been attacked by the fever the last season than during former years, and of these few a very small number died, the fever having proved much less malignant than it was ever known to be before. This circumstance led the inhabitants to hope, that as the country became more cleared it would become much more healthy. It is well known, indeed, that many parts of the country, which were extremely healthy while they remained covered with wood, and which also proved healthy after they had been generally cleared and settled, were very much otherwise when the trees were first cut down: this has been imputed to the vapours arising from the newly cleared lands on their being first exposed to the burning rays of the sun, and which, whilst the newly cleared spots remain surrounded by woods, there is not a sufficient circulation of air to dispel. The unhealthiness of the country at present does not deter numbers of people from coming to settle here every year, and few parts of North America can boast of a more rapid improvement than the Genesee country during the last four years. [Sidenote: SMALL TOWNS.]