ABSTRACTS OF TECHNICAL ARTICLES 441 



distances. Components were observed from regions up to 4000 miles dis- 

 tant. Direction-of -arrival measurements using steerable arrays operating 

 on the musa principle indicate that these multiple echoes are scattered 

 from regions along the transmitted beam. Vertical angle-of-arrival meas- 

 urements using a musa receiving system indicate that the surface of the 

 earth may be the source of scattering. 



Similarities between multiple echoes and southerly deviated waves from 

 European transmitters have been found which indicate that the same 

 phenomena may be responsible for both. 



Evolution by Design.^ Reginald L. Jones. The evolution of the tele- 

 phone plant is characterized by planning and invention. This article de- 

 scribes the Bell Telephone Laboratories' method of developing new and 

 improved telephone apparatus by integrating the creative efforts of tech- 

 nicians in various fields of research and engineering. For telephone readers 

 the recent development histories of telephone drop wire, relay, and station 

 receiver are chosen to illustrate the problems encountered. Other appa- 

 ratus, some of which is shown by the figures, follows a similar development 

 pattern. New materials, improved processes of manufacture, economy in 

 maintenance, and a better understanding of convenient use — all play con- 

 tinuing parts in the forward march of telephone design. 



Television Transmission.^ M. E. Strieby and C. L. Weis. Experi- 

 ments in the transmission of television signals over wire lines have been 

 made from time to time as the television art has developed. The present 

 paper discusses experiments made during the summer of 1940 with 441- 

 line, 30-frame interlaced signals transmitted over coaxial cable and other 

 telephone facilities. Some of the general problems of wire transmission 

 have been included. In particular, the results of transmission studies on 

 a system linking New York and Philadelphia are reported. 



* Bell Telephone Magazine. August 1941. 

 ^Proc. I.R.E., July 1941. 



