56 KITE WORK OF THE WEATHER BUREAU 



recording instruments attached to kites. Independent observations 

 at single stations had Ijeen made previously by private individuals, 

 notal>ly those under tlie direction of Mr A. Jv. 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 i)0.ssible to con- 

 struct daily synchronous cliarts 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 tlie 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. 



Tlie 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 da3\s ascensions were imi>ossible, 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. 



