Page:Notes on the State of Virginia (1802).djvu/117

ſame paralel of latitude weſtwardly, the climate becomes colder in like manner as when you proceed northwardly. This continues to be the caſe till you attain the ſummit of the Alleghaney, which is the higheſt land between the ocean and the Miſſiſippi. From thence, deſcending in the ſame latitude to the Miſſiſippi, the change reverſes; and, if we may believe travellers, it becomes warmer there than it is in the ſame latitude on the ſea ſide. Their teſtimony is ſtrengthened by the vegetables and animals which ſubſiſt and multiply there naturally, and do not on our ſea-coaſt. Thus catalpas grow ſpontaneouſly on the Miſſiſippi, as far as the latitude of 37°, and reeds as far as 38°. Perroquets even winter on the Scioto, in the 39th degree of latitude. In the ſummer of 1779, when the thermometer was at 90° at Monticello, and 96 at Williamſburg, it was 110°. at Kaſkaſkia. Perhaps the mountain, which overhangs this village on the north ſide, may, by its reflection, have contributed ſomewhat to produce this heat. The difference of temperature of the air at the ſea-coaſt, or on the Cheſapeak bay, and at the Alleghaney, has not been aſcertained: but cotemporary obſervations, made at Williamſburgh, or in its neighborhood, and at Monticello, which is on the moſt eaſtern ridge of the mountains, called the South weſt, where they are interſected by the Rivanna, have furniſhed a ratio by which that difference may in ſome degree be conjectured. Theſe obſervations make the difference between Williamſburg and the neareſt mountains, at the poſition before-mentioned, to be on an average 61/8 degrees of Farenheit's thermometer. Some allowance, however, is to be made for the difference of latitude