falls low enough to freeze it.] In our Northern States, irregular as is the climate, the first autumnal snows pretty constantly fall before the ground is frozen at all, or when the frost extends at most to the depth of only a few inches. [Footnote: The hard autumnal frosts are usually preceded by heavy rains which thoroughly moisten the soil, and it is a common saying in the North that "the ground will not freeze till the swamps are full."] In the woods, especially those situated upon the elevated ridges which supply the natural irrigation of the soil and feed the perennial fountains and streams, the ground remains covered with snow during the winter; for the trees protect the snow from blowing from the general surface into the depressions, and new accessions are received before the covering deposited by the first fall is melted. Snow is of a color unfavorable for radiation, but, even when it is of considerable thickness, it is not wholly impervious to the rays of the sun, and for this reason, as well as from the warmth of lower strata, the frozen crust of the soil, if one has been formed, is soon thawed, and does not again fall below the freezing-point during the winter. [Footnote: Dr. Williams, of Vermont, made some observations on the comparative temperature of the soil in open and in wooded ground In the years 1789 and 1791, but they generally belonged to the warmer months, and I do not know that any extensive series of comparisons between the temperature of the ground in the woods and in the fields has been attempted in America. Dr. Williams's thermometer was sunk to the depth of ten inches, and gave the following results: ---- | Temperature | Temperature | Time. | of ground in| of ground in| Difference. | pasture. | woods. | ---- May 23......................| 52 | 46 | 6 " 28......................| 57 | 48 | 9 June 15......................| 64 | 51 | 13 " 27......................| 62 | 51 | 11 July 16......................| 62 | 51 | 11 " 30......................| 65 1/2 | 55 1/2 | 10 Aug. 15......................| 68 | 58 | 10 " 31......................| 59 1/2 | 55 | 4 1/2 Sept.15......................| 59 1/2 | 55 | 4 1/2 Oct. 1......................| 59 1/2 | 55 | 4 1/2 " 15......................| 49 | 49 | 0 Nov. 1......................| 43 | 43 | 0 " 16......................| 43 1/2 | 43 1/2 | 0