320 THE EXPLORATION OF THE FREE AIR. 



tious. Some of the kites stand nearly 9 feet high and have 64 square 

 feet of lifting surface. A very efficient but complex form is Lamson's 

 aero-curve folding kite which has the sustaining surfaces of its forward 

 cell curved like a bird's wing, while the rear cell, with triangular super- 

 posed planes, acts as a tail or rudder. Figure 1 shows this kite in position 

 to rise from the ground. In the bridle or hanger of the Blue Hill kites 

 an elastic cord has been inserted which stretches when the wind pres- 

 sure increases beyoud a safe amount, causing the kite to fly more nearly 

 horizontal while the gust lasts. These kites may be started in a wind 

 which blows more than 12 miles an hour, and they continue to fly in 

 gales of 50 miles per hour. On Blue Hill the average velocity of the 

 wind for the year is 18 miles an hour, consequently there are few days 

 when kites can not be flown there. The flying cords are fastened into 

 a ring at the end of the wire, where the meteorograph is hung. The main 

 line is steel " music wire," capable of withstanding a pull of 300 pounds, 

 and weighing 15 pounds per mile. Several miles of this wire are spliced 

 together with the greatest care, special pains being taken that no sharp 

 bends occur which would cause it to break. To manipulate this wire 

 the deep-sea sounding apparatus, driven by steam, has been modified 

 by Mr. Fergusson to pull obliquely downwards. The wire from the 

 kites passes over a swiveling pulley which follows the direction of the 

 wire and registers on a dial the exact length of wire unreeled. Next 

 the wire bears against a pulley carried by a strong sj)iral spring, by 

 which the pull upon the wire at all times is graphically recorded on a 

 paper-covered drum turned by clockwork. The wire then passes several 

 times around the strain pulley and is finally coiled under slight tensions 

 upon a large storage drum. When the kites are to be pulled down, 

 the strain pulley is driven by a belt from a 2-horsepower Shipman auto- 

 matic steam engine. When they are rising, the belt is disconnected 

 and the pull of the kites is sufficient to unreel the wire. The usual rate 

 of speed at which the wire is drawn in is from 3 to 6 miles an hour. 

 Figure 2 shows the steam windlass and its constructor. In order to lift 

 the increasing weight of wire it is customary to attach kites at various 

 points on the wire, according to the pull upon it, so that nearly the 

 same angular elevation may be maintained. This is done by screwing 

 on the wire aluminum clamj)S to which the flying lines of the kites are 

 tied or connected by toggles. The meteorograph, made in Paris, is 

 contained in an aluminum cage of about a foot cube and weighs com- 

 plete less than 3 pounds. The cage contains a barometer, a thermom- 

 eter, and a hygrometer which all record their readings automatically on 

 one cylinder turned by clockwork in twelve hours. It is only necessary 

 to screen the thermometer from the sun's rays to obtain the true air 

 temj)erature, since the wind insures the circulation of air. A kite 

 meteorograph just constructed by Mr. Fergusson contains an anemom- 

 ter, barometer, thermometer, and hygrometer, and yet weighs but 3 

 pounds. Figure 3 shows this instrument in the air supported by two 

 of the largest Hargrave kites. 



