Page:Handbook of Meteorology.djvu/141



The floating dust of the air has a marked effect upon its temperature. Benjamin Franklin noted this fact. During several months in 1783, the air was filled with floating volcanic dust. “The sun’s rays were indeed rendered so faint in passing through it that, when collected in the focus of a burning glass, they would scarcely kindle brown paper.” The heating power of the sun was so feeble that freezing temperatures began nearly a month before their normal occurrence. “Delaware River was closed in November and remained ice-bound until late in March.”

The years 1812-1816 were years of great volcanic activity, and the air was loaded with floating dust. As a result, the year 18 16 has gone into history as the “year without any summer”—the year of “eighteen hundred and froze-to-death.” In Vermont snow fell and frosts occurred every month of that year. On the 8th of June, snow on the uplands was 5 or 6 inches deep.

Humphreys has shown that, with a blanket of volcanic