Page:Popular Science Monthly Volume 45.djvu/352

336. The value of the work can be judged by Jefferson's statements under Query 7 in his Notes on Virginia:

"Journals of observations on the quantity of rain and degree of heat being lengthy, confused, and too minute to produce general and distinct ideas, I have taken five years' observations, to wit from 1772 to 1777, made in Williamsburg and its neighborhood, have reduced them to an average for every month in the year, and stated those averages in the following table, adding an analytical view of the winds for the same period."

Then follows quite a long table of average temperatures and wind directions of great interest to the meteorologist. Thinking that some noteworthy differences might exist between the northeast and northwest winds at the two stations, a second table was constructed by reducing observations at the two places for nine months to the "four points perpendicular to and parallel to the coast. It may be seen that the southwest wind prevails equally at both places, that the northeast is next to this the principal wind toward the seacoast, and the northwest is the predominant wind toward the mountains; . . . the northeast wind is loaded with vapor insomuch that the salt-makers have found that their crystals would not shoot while that blows; it brings a distressing chill, and is heavy and oppressive to the spirits; the northwest is dry, cooling, elastic, and animating."

Even our valuable Crop Bulletin was foreshadowed by these early workers. We find it recorded that "white frosts are frequent when the thermometer is at 47º and have killed young plants of Indian corn at 48º, and have even been known at 54. Black frost and even ice have been produced at 38º."

Finally, that much-discussed matter, change in climate, did not escape their notice. "A change in climate," they claim, "is taking place very sensibly." This was written in 1781. "Both heats and colds are becoming much more moderate within memory even of the middle-aged. Snows are less frequent and less deep. They do not often lie below the mountains more than one, two, or three days, and very rarely a week."

And then follows a very evident reference to that even then well-known personage, the oldest inhabitant:

"The snows are remembered to have been formerly frequent, deep, and of long continuance. The elderly inform me that the earth used to be covered with snow about three months in every year."

From snows and winds these meteorologists turned their attention to rainbows, and from rainbows to water vapor and steam. Curiously enough, it is in a letter to Jefferson, mostly about the rainbow, that Madison gives the latest information about a boat to be propelled by steam and which "General W