would dive even when high in air. Once we kept the kite aloft from the forenoon until late at night, but that was something unusual.
Passing now over six years in which we had been busy measuring 
Electrical Potential of the Air. Small collector about fifteen feet from ground; kite about five hundred feet from ground. the electrification of the air under all conditions, and discovering, for example, that a snowstorm was almost identical with a thunderstorm in its tremendous electrical changes, we come to the year 1891, when we again flew kites for the purpose of electrically exploring the air. Our experiments at the top of the Washington Monument in 1885 and 1886 (especially those during severe thunderstorms, when we obtained potentials as high as three and four thousand volts just before the lightning),
Multiple Quadrant Electrometer, July, 1892. Blue Hill Observatory.
had given us an insight into the strains and stresses in the air, and taught us what to expect at such times. There was still little improvement in the kite, but much better electrical appa-
