122 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Mich.; Madison, Wis.; San Francisco, Calif.; San Juan, P. R. ; 

 and Washington, D. C. The observations are made twice daily at 

 the six kite stations and at Key West, Fla., and Washington, D. C, 

 and once each day at the remaining stations, and the computed wind 

 conditions at various heights are telegraphed to district forecast 

 centers at Washington, D. C. ; Chicago, 111. ; and San Francisco, 

 Calif. ; where they form the basis for " flying weather " forecasts 

 issued to the military, naval, and postal aviation services. 



Special observations have been made, when requested, for use in 

 connection with long-distance flights, free-balloon races, etc. 



Observations with two theodolites have been continued, whenever 

 opportunity afforded, in order to check the accuracy of the formula 

 for rate of ascent of balloons and the behavior of the balloons them- 

 selves at high altitudes. These observations have shown that the 

 revised rate of ascent formula gives extremely reliable results, except 

 ■when there are pronounced vertical movements in the atmosphere. 

 Even then the error is appreciable only in the lower layers. 



Cooperation. — Effective cooperation with the Army and Navy 

 meteorological services has been continued throughout the year. 

 Each of these services maintains a number of pilot-balloon stations, 

 whose primary purpose is to furnish data of immediate local in- 

 terest to aviators at flying fields. These observations are also tele- 

 graphed to district forecast centers of the Weather Bureau for use 

 in issuing " flying weather " forecasts. They thus supplement, in 

 a very helpful way, the observations made at Weather Bureau aero- 

 logical stations. In addition to the stations in the United States 

 proper the Navy maintains one at Santo Domingo, Dominican Re- 

 public, and one at Coco Solo, Canal Zone, which, together with 

 those of the Weather Bureau ai San Juan, P. R., and Key West, 

 Fla., furnish information of value in connection with the de- 

 velopment and movement of hurricanes. A much larger number 

 of stations is necessary, however, to make this service as effective as 

 it should be. 



In cooperation with representatives of the United States Air 

 Service, the air-mail flight records for one year were analyzed and 

 studied in connection with the Weather Bureau's kite and balloon 

 data, and the results of this investigation were published under the 

 title " The Wind Factor in Flight : An Analysis of One Year's 

 Record of the Air Mail." 



The official in charge of aerological investigation is the Weather 

 Bureau representative on a sectional committee that is preparing 

 an aeronautical safety code. The committee is composed of repre- 

 sentatives of the Departments of War, Navy, Commerce, and Post 

 Office, the Society of Automotive Engineers, the National Aeronaut- 

 ical Association, and aircraft manufacturers. The code, when com- 

 pleted, will provide regulations for the design and manufacture of 

 aircraft, qualifications of pilots, establishment of airdromes and air- 

 ways, and dissemination of meteorological forecasts and warnings, 

 etc. 



Central Office. — All observations made at kite and balloon sta- 

 tions by the Army and Navy, as well as by the Weather Bureau, are 

 forwarded to the central office of the Weather Bureau for final 

 reduction and study. Data based upon these observations are fur- 

 nished in answer to numerous inquiries, not only from other Gov- 



