ABSTRACTS OF TECHNICAL ARTICLES 245 



preictically the entire world. The conference formulated a treaty, 

 known as the International Telecommunication Convention, to which 

 are attached Reg;ulations relating to (1) the allocation of frequency 

 bands for radio services, the reduction of radio interference and the 

 operation of marine radio service, (2) the transmission of telegrams over 

 international telegraph and cable circuits, and (3) the handling of 

 telephone calls over the European telephone system. 



Directional Studies of Atmospherics at High Frequencies.^ Karl G. 

 Jansky. a system for recording the direction of arrival and intensity 

 of static on short waves is described. The system consists of a rotating 

 directional antenna array, a double detection receiver and an energy 

 operated automatic recorder. The operation of the system is such 

 that the output of the receiver is kept constant regardless of the in- 

 tensity of the static. 



Data obtained with this system show the presence of three separate 

 groups of static: Group 1, static from local thunderstorms; Group 2, 

 static from distant thunderstorms, and Group 3, a steady hiss type 

 static of unknown origin. 



Curves are given showing the direction of arrival and intensity of 

 static of the first group plotted against time of day and for several 

 different thunderstorms. 



Static of the second group was found to correspond to that on long 

 waves in the direction of arrival and is heard only when the long wave 

 static is very strong. The static of this group comes most of the time 

 from directions lying between southeast and southwest as does the long 

 wave static. 



Curves are given showing the direction of arrival of static of group 

 three plotted against time of day. The direction varies gradually 

 throughout the day going almost completely around the compass in 

 24 hours. The evidence indicates that the source of this static is 

 somehow associated with the sun. 



A Note on an Automatic Field Strength and Static Recorder. W. W. 

 MuTCH.^ Many types of instruments have been used to record field 

 intensities, both of signals and static, and the varying requirements 

 have produced many widely different pieces of apparatus. One may 

 desire to study the changes taking place over a period as short as one 

 millisecond, or as long as an eleven-year sun-spot period. Obviously 

 the same instrument would not do for both studies. The development 

 work on the recorder described here was started some years ago with 



' Proc. I. R. E., December, 1932. 

 5 Proc. I. R. £., December, 1932. 



