186 BELL SYSTEM TECHNICAL JOURNAL 



2. The current is proportional to the voltage only so long as the 

 current is small; otherwise the products of electrolysis alter the 

 conductivity. 



3. Polarization currents are caused by the Ba and O which are 

 produced by electrolysis. These currents decrease rapidly even at 

 temperatures near 500° K., thus showing that Ba and O diffuse at 

 low temperatures. 



Some Observations of the Behavior of Earth Currents and their Cor- 

 relation with Magnetic Disturbances and Radio Transmission.^ Isabel 

 S. Bemis. This paper presents correlations between the abnormal 

 earth currents noted during magnetic storms and transoceanic radio 

 transmission on both long and short waves. The radio transmission 

 data were collected on the telephone circuits operating between New 

 York and London and between New York and Buenos Aires. The 

 earth current data were collected on two Bell System lines extending 

 approximately a hundred miles north and west from New York. 

 The results of this w^ork establish facts which have been known in a 

 general way for some time. 



The direction of flow of abnormal earth currents in the neighborhood 

 of New York seems to be along a northwest-southeast line. Coincident 

 with such abnormal currents are periods of poor short-wave radio 

 transmission. However, on long waves, daylight transmission over 

 transatlantic distances is improved. On the short-wave circuit to 

 Buenos Aires, transmission is adversely affected but only to a moderate 

 extent. 



TJie Propagation of Short Radio Waves over the North Atlantic.'^ 

 C. R. Burrows. Transmission conditions for each season are shown 

 by "surfaces" giving the received field strength as a function of time 

 of day and frequency. These show that frequencies near 18 mc are 

 best for daytime transmission. In summer the best frequencies for 

 nighttime transmission are those near 9 mc. In winter an additional 

 frequency near 6 mc is required during the middle of the night. A 

 frequency (such as 14 mc) intermediate between the day and night 

 frequency is useful during the transition period between total daylight 

 and total darkness over the path. Day-to-day variations change the 

 periods of usefulness of these frequencies. In particular the period of 

 usefulness on 14 mc sometimes extends so that it is the best daytime 

 frequency. 



Transmission conditions on undisturbed days were found to be the 



^Proc. I. R. E., November, 1931. 

 *Proc. I. R. E., September, 1931. 



