The winds in fair weather in the spring, and in warm weather in the summer, blow from the south-west and from west-north-west. The _raw_ air before-mentioned comes from the north-east. The south-west winds likewise usually bring with them those showers of rain in the spring and summer which refresh the earth. They moreover moderate the heat of the weather, provided they are succeeded by a north-west wind. Now and then showers of rain come from the west-north-west. There is a common fact connected with the account of the usual winds in Pennsylvania, which it may not be improper to mention in this place. While the clouds are seen flying from the south-west, the _scud_, as it is called, or a light vapour, is seen at the same time flying below the clouds from the north-east. The moisture of the air is much greater than formerly, occasioned probably by the exhalations which in former years fell in the form of snow, now descending in the form of rain. The depth of the snow is sometimes between two and three feet, but in general seldom exceeds between six and nine inches. Hail frequently descends with snow in winter. Once in four or five years large and heavy showers of hail fall in the spring and summer. They generally run in narrow veins (as they are called) of thirty or forty miles in length, and two or three miles in breadth. The heaviest shower of hail that is remembered in Philadelphia, did not extend in breadth more than half a mile north and south. Some of the stones weighed half an ounce. The windows of many houses were broken by them. This shower fell in May, 1783. From sudden changes in the air, rain and snow often fall together, forming what is commonly called _sleet_. In the uncultivated parts of the state, the snow sometimes lies on the ground till the first week in April. The backwardness of the spring has been ascribed to the passage of the air over the undissolved beds of snow and ice which usually remain, after the winter months are past, on the north-west grounds and waters of the state, and of the adjacent country. The dissolution of the ice and snow in the spring is sometimes so sudden as to swell the creeks and rivers in every part of the state to such a degree, as not only to lay waste the hopes of the husbandman from the produce of his lands, but in some instances to sweep his barns, stables, and even his dwelling house into their currents[32]. The wind, during a general thaw, comes from the south-west or south-east. [32] The following account of the thaw of the river Susquehannah, in the spring of 1784, was published by the author in the Columbian Magazine, for November, 1786. It may serve to illustrate a fact related formerly in the history of the winters in Pennsylvania, as well as to exhibit an extraordinary instance of the destructive effects of a sudden thaw.