Still another device employed by meteorologists is the pilot-balloon. This is also a free balloon, but carries no meteorological instruments. Its motion in the air is followed by means of a theodolite, and it serves to show the speed and direction of the wind at different levels. During the winter of 1912-13 a pilot-balloon sent up from Godhavn, Greenland, by a Danish exploring expedition reached the unprecedented altitude of more than 24 miles.
PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION
ILLUSTRATION FOR THE MENTOR, VOL. 4, No. 10, SERIAL No. 110
COPYRIGHT, 1916, BY THE MENTOR ASSOCIATION, INC.
THE EFFECTS OF SNOW AND ICE—THE CAMPUS, PRINCETON UNIVERSITY
OUR WINTERS
Monograph Number Six in The Mentor Reading Course
In the year 1781 Thomas Jefferson wrote in his "Notes on Virginia": "A change of climate is taking place very sensibly. *** 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. 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."
Probably long before the white man came to America the patriarchs of the Indian tribes regaled the young men and maidens gathered about the campfire with reminiscences of the deep snows that prevailed in a previous generation.