ABSTRACTS OF TECHNICAL ARTICLES 745 



same time maintain a constant phase angle between the two waves. 

 Typical circuits are discussed which make use of copper oxide as the 

 modulator elements. 



Seasonal Cosmic-Ray Effects at Sea Level.^ R. A. Millikan, 

 H. V. Neher and D. O. Smith. By sending a Neher self-recording 

 electroscope in a 10-cm lead shield repeatedly on a slow Norwegian 

 steamer over the route Vancouver-Los Angeles, around South America 

 and return to Los Angeles and Vancouver, we find (1) as heretofore 

 an equatorial dip measured from Los Angeles of seven per cent on the 

 western side of South America, eight per cent on the eastern side; 

 (2) no measurable seasonal effect, or winter-summer differences, at all 

 in the voyage from Los Angeles to the Straits of Magellan; (3) as 

 heretofore constancy in cosmic-ray intensity in summer and fall, 

 within the limits of uncertainty imposed by fluctuations estimated 

 at not over one per cent, on the voyage between Los Angeles and 

 Vancouver; (4) but in winter and spring an increase of as much as 

 two or three per cent between Los Angeles and Vancouver. This is 

 interpreted as the atmospheric-temperature effect earlier studied by 

 Hess, Compton, and their respective collaborators. 



Some Engineering Considerations in Loading Circuits}^ J. A. 

 Parrott. This paper describes the various loading arrangements 

 used on toll entrance and intermediate cable circuits and discusses the 

 transmission benefits obtained by loading and some of the important 

 problems in the consideration of loading railroad entrance and inter- 

 mediate cables. In addition to voice frequency loading, loading for 

 the lower frequency carrier systems such as the Type H is also 

 discussed. 



The Formation of Metallic Bridges between Separated Contacts}^ 

 G. L. Pearson. Low resistance bridges were formed between gold, 

 steel and carbon electrodes having separations of 2-70 X 10~'^ cm by 

 applying voltages less than the minimum sparking potential. For a 

 given pair of electrodes the field required to form the bridges is a 

 constant and is 5-16 X 10^ volts per centimeter. Measurements of 

 the temperature coefficient of resistance of the bridges identify them 

 as consisting of the material of the electrodes. A study of their re- 

 sistance as a function of the displacement of one of the electrodes 

 shows that they may be pulled out as well as crushed. At voltages 



" Phys. Rev., September 15, 1939. 



^'' Proc, Assoc. Amer. R.R., Telegraph and Telephone Section, April 1939. 



11 Phys. Rev., September 1, 1939. 



