Page:Popular Science Monthly Volume 53.djvu/70
THE POPULAR SCIENCE MONTHLY.
pended from four Hargrave cells to a height of forty-two feet above New York Bay.
The later instance referred to is thoroughly verified and reliable. It is the ascent made by Mr. Charles H. Tamson, near Portland, Maine, on June ]9, 1897, to an elevation of fifty feet with a single kite of the form devised by him. In most other exploits of this kind the aëronaut has been drawn up by a pulley to kites already well
poised aloft; but Mr. Tamson started with his kite, running along on the ground as it was drawn forward, and going up with it when the initial impulse had been gained. The Lamson kite is constructed on an original idea, though it is a combination of the flat and the cellular types. The gain in height of ascent by kites since experiments began at Blue Hill has been at the rate of about one thousand feet each year. The highest ascent previous to 1897 was made by a six-foot kite of the Malay or Eddy pattern, on October 8, 1896. The elevation attained was 9,400 feet above tide-water, 9,300 feet above the surrounding country, and 8,770 feet above the top of Blue Hill, which is 635 feet above the sea—in full view from its summit. The meteorological instruments made records up to a height of 9,375 feet.
A higher ascent was made early in the autumn of 1897 at Blue Hill, when the leader of a tandem, a Lamson kite, reached an elevation of 11,060 feet (two and a tenth miles), where it was broken by the strong wind. The observatory people now hope that, with the Lamson kite as a leader, they will be able to send their instruments to a much greater height.
The elevation of the kites is determined by the same means used for mountains—the pressure of the atmosphere as recorded in the barometer, and calculations with the angle the kites make with the extremities of a base line. The string has too much indeterminate sag to furnish an accurate measurement.
It has been found that with an increase of altitude a constantly lowering temperature is encountered, except rarely, when there is an overlying warm stratum, ushering in a spell of unseasonably warm weather. At the approach of these warm tides, when the