WEATHER BUREAU. 51 



STORM-WARNING SERVICE. 



The work of improving the storm-warning service by the installa- 

 tion of the three-lantern system has gone forward, the installation on 

 the Great Lakes having been completed in the fall of 1916. Prelimi- 

 nary plans for the installation on the South Atlantic and Gulf coast 

 have been completed and material is either on the ground or en route. 

 Plans for the extension of the system to the North Atlantic coast 

 are well underwa}'. 



AEROLOGICAL INVESTIGATIONS. 



The work of obtaining free-air observations by means of kites 

 has been continued at the Drexel aerological station during the past 

 year. The data thus obtained include atmospheric pressure, tem- 

 perature, humidity, wind velocity and direction, electric potential, 

 and cloud altitude and movement. Flights were made on all but 11 

 days during the year, and a daily telegram giving the atmospheric 

 conditions at one or two selected levels in the free air has been sent 

 to the forecast centers of the Weather Bureau at Washington, D. C, 

 and Chicago, 111. In addition to the daily observations, series of 

 observations continuing for a period of 30 to 36 hours have been made 

 whenever conditions were favorable. The data thus obtained enable 

 the bureau to follow atmospheric changes in considerable detail. In 

 all, 516 observations have been made during the year — July 1, 1916, to 

 June 30, 1917. Of these 160 were made in 21 different diurnal series, 

 the remaining 356 being made as daily observations. 



Plans have been made for more practical application of the results 

 of free-air investigations to problems connected with aeronautics 

 and the firing of projectiles. With this end in view the bureau 

 furnished an exhibit at the Aeronautic Exposition held in Ne_w York 

 City February 8-15, 1917, 'and also participated in the discussion 

 held at that time under the auspices of the Aero Club of America. 

 A paper on "Aerology in Aid of Aeronautics " was presented at the 

 symposiimi on aeronautics before the American Philosophical So- 

 ciety in Philadelphia on April 13, 1917. This paper is to be published 

 by that society. 



Since February, 1917, considerable work has been done in the 

 preparation of a manual or handbook for aeronauts. It will include 

 a survey of the different parts of the United States, showing relative 

 suitability of various localities for the establishment of aeronautic 

 stations and will also contain a summary of free-air conditions most 

 likely to be met with under different types of pressure distribution 

 at the earth's surface. Copy for this book has been nearly completed 

 and will soon be ready for publication. Frequent conferences have 

 been held with officials of the aeronautic branches of the War and 

 Navy Departments with a view to establishing closer cooperation 

 between these services and this bureau. As a result of these confer- 

 ences, plans are being perfected for making free-air observations in 

 aid of aeronautics and the firing of projectiles at several of the 

 training camps, including those at San Diego, Cal., Pensacola, Fla., 

 Mineola, N. Y., Hampton, Ya., and others. Free-air wind data, 

 as observed at the Drexel aerological station, are furnished daily 



