ULTRA-SHORT-WAVE TRANSMISSION 519 



B. van der Pol and Bremmer, Phil. Mag., Vol. 24, p. 141, 1937; Vol. 24, p. 825, 

 1937. 



5. Miss M. C. Gray, paper to be published.* 



6. Schelleng, Burrows and Ferrell, Froc. I. R. E., Vol. 21, p. 427, 1933. 



7. Colwell and Friend, Nature, Vol. 137, p. 782, 1936; Phys. Rev., Vol. 50, p. 632, 



1936; Colwell, Friend, Hall and Hill, Nature, Vol. 138, p. 245, 1936; Friend 

 and Colwell, Proc. I. R. E., Vol. 25, p. 1531, 1937. 



8. Watson Watt, Wilkins and Bowen, Proc. Roy. Soc, A, Vol. 161, p. 181, 1937. 



9. Q.S.T., Vol. 21, p. 27, 1937, July. 



10. Englund, Crawford and Mumford, Proc. I. R. E., Vol. 21, p. 464, 1933. 



11. H. C. Willett, Bull. Amer. Meteor. Soc, Vol. 17, p. 213, 1936. 



12. Beal, Television, Vol. 2, p. 15, 1937, R.C.A. Inst's. Press. 



13. Englund, Crawford and Mumford, Nature, Vol. 137, p. 743, 1936. 



* The case of vertical polarization is treated by references 4, that of horizontal 

 polarization by reference 5. 



