National Geographic : 1900 Feb
56 KITE WORK OF THE WEATHER BUREA U recording instruments attached to kites. Independent observations at single stations had been made previously by private individuals, notably those under the direction of Mr A. L. Rotch at Blue Hill Observatory, Mass.; but observations from a single station, while ex tremely valuable in themselves, are useless when comparative results are sought. It was the hope of the Chief of the Weather Bureau in establishing a chain of kite stations that it would be possible to con struct daily synchronous charts of pressure, temperature, and wind velocity from the data thus obtained for different elevations up to at least 5,000 feet, and that from a study of these charts a marked ad vance could be made in the present system of weather forecasting. An immense amount of time, labor, and experimentation was neces sary before the kite apparatus could be brought to a high state of efficiency, the observers properly instructed, and the stations estab lished, and it was not until the spring of the year 1898 that the work was fairly launched. In all seventeen stations were established, mostly in the great river valleys and the Upper Lake region. The standard kite used was constructed largely after the Hargrave model, with various improvements suggested by actual trial and ex periment. At some stations the kite contained 68 square feet of surface, at others a smaller kite of 45 square feet was used, and at still others a slightly larger one of 72 square feet of surface was occasionally used. The meteorograph, an instrument for recording automatically the pressure, temperature, and relative humidity of the air, was devised by Prof. C. F. Marvin of the Weather Bureau. The mechanisms were inclosed in a light aluminum case, the whole being suspended within the framework of the kite. It was soon discovered that the hope of a daily synchronous chart of the conditions existing at high altitudes could not be realized. On many days ascensions were impossible, owing to the absence of suffi cient wind to sustain the kites. Neither could they be flown in stormy weather. There were made only 46 per cent of the total number of ascensions which would have been possible had wind and weather conditions been favorable. The percentage varied from 75 at Dodge City, Kans., to 12 at Knoxville, Tenn. When by chance ascensions were made at a majority of the stations on any one day, varying wind conditions necessitated their being made at different hours, thereby * Summarized from Vertical Gradients of Temperature, Pressure, and Wind Direction: Weather Bureau Bulletin F, U. S. Department of Agriculture.