STUDIES IN ATMOSPHERIC ELECTRICITY 



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factors were not adopted for use because examination of 

 later parallel observations with the eye-reading appara- 

 tus and the recorder made while at sea between Reykja- 

 vik and Barbados, taken in conjunction with the Barbados 

 reduction factor results (series 3), has indicated that the 

 factors for the eye -reading apparatus for sail positions 

 MUBP and MUBS are nearer the Kitts Point value of 3.3 

 than the Reykjavik value of 2.2. 



The sets of parallel observations between the eye- 

 reading and recording instruments on the stern rail, 

 made after leaving Reykjavik, were obtained between 

 August 10 and September 14, 1928. August 10 was the 

 earliest available date because prior to that time fre- 

 quent difficulties were encountered with the recorder. 

 Recorder 4946 had been in constant use since leaving 

 Hamburg on July 7 but on August 9 recorder 4947 was 

 substituted for 4946, and it remained in operation until 

 August 20. After that date, the two recorders were al- 

 ternated at short intervals until August 30, and instru- 

 mental adjustments were made on both recorders to 

 secure the best possible photographic records. After 

 August 30, recorder 4946 was permanently installed as 

 the stern recorder. Twenty-four sets of data were ob- 

 tained for sail position MUBP between August 10 and 



September 14, and nine sets for MUBS, as shown in table 

 4, where the average value of the ratio of eye-reading to 

 recorder measurements for MUBP is seen to be 0.23 and 

 for MUBS to be 0.22. These ratios will be used later in 

 connection with the results obtained in series 3 at Bar- 

 bados. 



For series 3 only recording apparatus was emploved 

 on shore and on the ship. The shore instrument was 

 carefully housed for protection against the weather, and 

 both ship and shore installations were allowed to operate 

 continuously for thirty-eight hours on September 27, 28, 

 and 29. FYom this extended period it has been possible 

 to select the hours during which the most favorable con- 

 ditions existed for the observations. Fogging of the 

 shore record caused the loss of several hours of data, 

 and bad weather caused the atmospheric potentials to 

 vary greatly for a period of five hours. In addition, spi- 

 der webs on the shore apparatus prevented successful 

 operation of the instrument at various times. Altogether 

 these difficulties accounted for twenty-two hours of un- 

 usable record. The factors for the remaining sixteen 

 hours show very good agreement among themselves. 

 These are shown in table 5. 



Table 4. Simultaneous values of potential by stern no. 2 and recorder appartus, 

 to determine ratio between them, Carnegie cruise Vn 



