336 THE POPULAR SCIENCE MONTHLY. 



ginia. The value of the work can be judged by Jefferson's state- 

 ments 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 gen- 

 eral and distinct ideas, I have taken five years' observations, to 

 wit from 1772 to 1777, made in Williamsburg and its neighbor- 

 hood, 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 north- 

 east 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 fre- 

 quent when the thermometer is at 47 and have killed young 

 plants of Indian corn at 48, and have even been known at 54. 

 Black frost and even ice have been produced at .38|^." 



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 mem- 

 ory 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 inhahitant : 



" 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 at- 

 tention 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 



