[1] A tail will prevent any kite from turning over, or "diving," because its weight keeps the lower end down while the pressure of the wind on the tail also pulls the lower end backward and maintains the necessary angle of the kite to the wind, the most efficient angle being about 22 degrees. Bending back the ends of the cross-stick gives stability to a kite because, when, on account of the eddies in the wind, a stronger pressure is exerted on one side of the kite, this side is driven backward, thereby presenting less effective surface to the wind, while as the other side comes forward more nearly at right angles to the wind, it receives greater pressure than before. In this way the equilibrium about the central stick is automatically maintained, the required inclination to the wind being secured by the greater surface presented to the wind below the point of attachment of the bridle. In 1891 Mr. Eddy lifted a minimum thermometer by several of these kites flown tandem, and proposed to obtain in this way data to forecast the weather. In the _Proceedings of the Aeronautical Conference_, held in connection with the Chicago Exposition, Prof. M. W. Harrington, then Chief of the U. S. Weather Bureau, quoted Mr. Eddy's estimate of the cost of exploring the air by means of kites flown in series, and advocated their use. Up to this time it does not appear that self-recording instruments--that is to say, those which make continuous graphic records--had been raised by kites. In the days of the early experimenters such instruments were too heavy and cumbersome to be lifted by the more or less unmanageable kites, but within the past few years M. Richard of Paris has made the simple and light recording instruments described in connection with balloons, which can be attached to kites. In this way it is possible to obtain simultaneous records at the kite and at a station on the ground, and from them to study the differences of temperature and humidity, and this seems to have been done first at Blue Hill Observatory. In August 1894 Mr. Eddy brought his kites to Blue Hill and with them lifted a Richard thermograph, which had been partly reconstructed of aluminium by Mr. Fergusson so that it weighed but 1-1/4 lbs., to the height of 1500 feet, and so the earliest automatic record of temperature was obtained by a kite. During the next summer, Mr. Eddy assisted again in the experiments at Blue Hill, and secured photographs of the Observatory and the hill by a camera carried between his kites to the height of a hundred feet or more.