240 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 10 



paper dealt with the principles underlying the calculation of the effects of 

 the distributed capacity and with the experimental verification of the cal- 

 culation of these effects. 



One of the effects due to the distributed capacity is the change in the 

 apparent inductance of the coil. This change may be shown to be due to 

 the fact that the current distribution in the coil is not uniform. On this 

 basis a calculation of the apparent inductance was made and hence the 

 "effective capacity" of a coil was derived. 



Similarlv the resistance of a coil was discussed. On account of the non- 

 uniform current, distribution based on the definition of resistance used for 

 the case of uniform current-distribution becomes inapplicable. The resis- 

 tance of the coil is redefined in such a way that it can be determined experi- 

 mentally and used to calculate the current in the coil when the coil is placed 

 in a known electric field. The experimental verification of the conclusions 

 derived was discussed. 



A considerable portion of the distributed capacity of a coil is due to the 

 capacity of the coil to ground. This capacity manifests itself when two 

 condensers are used in series with each other and with the coil. The assump- 

 tions underlying a theory of these phenomena were discussed and the theory 

 was shown to be verified experimentally. 



J. H. Bellinger and L. R. Whittemore: Radio signal fading phenom- 

 ena (presented by Mr. Bellinger, and illustrated). 



When radio first began to be used for long distance communication it was 

 noticed that signals were not transmitted as far during the day as during 

 the night-time. It has also been observed that night signals using the 

 shorter radio waves vary greatly in intensity from minute to minute. 



More recently, since radio direction finders have come into use, it has 

 been learned that great variations may occur in the direction of radio waves 

 as they arrive at the receiving station during the transmission of signals from 

 a given transmitting station. 



These and related phenomena have been recorded from time to time in 

 the literature, and various hypotheses have been brought forward in expla- 

 nation. The phenomena are dependent upon a large number of variable 

 quantities, such as the weather conditions, the nature of the country over 

 which transmission occurs, the surroundings of the transmitting and receiv- 

 ing stations, and the method of handling the receiving apparatus. Only 

 by a statistical study in which the results obtained simultaneously at a 

 large number of receiving stations are collected and tabulated may reliable 

 averages be obtained. 



Such a cooperative study is being carried on by the American Radio League 

 and the Bureau of Standards, tests being conducted in June and October, 

 1920, and January and April, 1921. In these tests from five to ten radio 

 stations transmit signals in succession. These signals are received simul- 

 taneously at about one hundred receiving stations whose operators are pro- 

 vided with forms for recording the variation in the intensity of the signals 

 as received. 



The paper described the results of the tests so far conducted and proposed 

 an explanation of the phenomena. This explanation associates the long- 

 distance radio transmission accomplished at night wnth the boundary of the 

 highly conducting outer portion of the atmosphere, which is also the origin 

 of auroral disturbances. Fluctuations in intensity are probably caused by 

 irregular absorption of the waves by masses of slightly ionized air through 



