162 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



hurricane velocity, while at other times the mountain top will be 

 shrouded by a coverinfr of cloud and rain — conditions that baffle any 

 attempt to launch a kite successfully. In the past twelve months 

 there were nine occasions when a kite flight or a balloon ascension 

 could not be made on account of stress of weather or because of other 

 hindering conditions, such as lack of hydrogen gas in winter. 



For the first few years flights at Mount Weather were made on 

 week days and holidays, but not on Sundays. The omission of Sun- 

 day flights was largely because of the general rule of the institution 

 to suspend activities on the seventh day in order that its employees 

 might get needed rest and recreation. Following a different arrange- 

 ment of the force and the addition of a storage battery, Sunday 

 flights began on July 18, 1909, and have continued regularly since, 

 except when prevented by adverse weather conditions. 



Progress in the exj^loration of the upper air must of necessity be 

 slow : First, the records obtained are not uniform, either as to the 

 altitude attained or the time of day the ascension is made; second, 

 owing to the varied character of weather conditions met with in the 

 course of a year it is not possible to distribute the flights in such a 

 way that a fair average of each set of conditions will be obtained. 

 In fact, many important changes occur of which no record is pos- 

 sible. Fortunately, the number of clays on which adverse weather 

 conditions prevent a kite flight or balloon ascension are few, there 

 having been, as before stated, but nine during the last year. But, 

 on the other hand, there were 10 days on which the altitude attained 

 was only 1,000 meters, or less, above sea level ; 97 days when the alti- 

 tude reached was between 1,000 and 2,000 meters;" il2 days when it 

 was between 2,000 and 3,000 meters; 74 days with a record of between 

 3,000 and 4,000 meters; 45 days with 4,000 to 5,000 meters, and 16 

 days when a height of more than 5,000 meters was attained. Thus 

 it will be seen that the material for study is composed of many 

 flights up to between 3,000 and 4,000 meters and a much smaller 

 number, about 17 per cent of the whole, above that height. It is 

 obvious that a direct comparison of atmospheric conditions, one day 

 with another, is not possible, except when daily records of approxi- 

 mately the same altitude are at hand. 



Since the weather conditions, especially those in an area of low 

 pressure, often preclude the sending up of a kite or captive balloon, 

 and since onl}^ that portion of the atmosphere up to about 10,000 feet 

 can be profitably investigated by their use, recourse must be had to 

 free small rubber balloons for sending instruments to greater heights. 

 The small balloons are filled with hj'^drogen gas, and may be sent up 

 singly or in tandem. When sent up singly a parachute is attached 

 so that when the balloon bursts the instrument will be brought safely 

 to the ground. Sounding balloons, as they are called, were used in 

 Europe as early as 1893. Their first use in this country was at St. 

 Louis in 1904 by Rotch. Their first use simultaneously at Uvo sta- 

 tions in this country was by the Mount Weather Research Observa- 

 tory in September and October, 1909, at Fort Omaha, Nebr., and 

 Indianapolis, Ind. The party at Fort Omaha obtained hydrogen 

 gas from the Signal Corps plant at that place. The party at In- 



« 1,000 iiieters=3,2Sl feet. 



