34 



OCEAN ATMOSPHERIC -ELECTRIC RESULTS 



Silver Chloride Batteries. --Two more batteries 

 have developed bad cells and the great pressure of cur- 

 rent work has prevented replacements. It is intended, 

 however, to make these replacements before leaving 

 Barbados. 



Comments 



Difficulties with Potential-Gradient Recorder. --Mr. 

 Parkinson's conclusions regarding these seem plausible. 

 We would suggest, however, that fibers as fine as are 

 admissible as regards sensitivity and size of image 

 should reduce disturbances of mechanical origin unless 

 these disturbances are really caused through vibration 

 of the invar rods and the lower support for the fibers. 

 Whenever the electrometer is opened for any cause the 

 invar rods and inner case should be inspected so as to 

 assure that all parts are rigidly fastened. As indicated 

 in the report, however, it is likely that the chief sources 

 of instability are electrical disturbances which may 

 arise from movements of the mainsail or the boom or 

 may be caused by space charges carried from spray by 

 gusts of wind. Disturbances arising in this way proba- 

 bly will act on the recorder chiefly by induction and, if 

 so, removing three of the four collectors would not re- 

 sult in much greater stability. If the capacitance to 

 earth of the shielded part of the collector system were 

 increased, however, the inductive effects would be re- 

 duced, and the effective collector activity would be cor- 

 respondingly reduced even with the four collectors in 



use. Hence such a device would be effective whether the 

 disturbances result from induction or from actual col- 

 lection of charge. This scheme should have another ad- 

 vantage over reducing the number of collectors, namely, 

 that the falsifying effect of insulation leak, as we see it, 

 is not increased even though the system may have so 

 much added capacitance that it takes five or ten minutes 

 to charge from zero to air potential. 



Although it has been possible to give this difficulty 

 only brief consideration, it seems likely that an attach- 

 ment which will correct it can be made up in the shop 

 and sent to the Carnegie for installation. 



Even with the recorder as operating during the 

 period August 10 to September 17, many diurnal-varia- 

 tion data are being obtained which, on preliminary in- 

 spection, seem valuable and at the rate of accumulation 

 during that period will soon outnumber the series ob- 

 tained on all previous cruises. The form in which these 

 data are tabulated seems very convenient. 



Radioactive Content Collector. --If this cannot be 

 made to function when the atomizer is used, the parts of 

 the old water dropper which are on the Carnegie should 

 be tried. In our opinion the spray from the atomizer 

 fouls the insulation under conditions aboard the Carne- 

 gie although in the laboratory it worked beautifully. 



Silver Chloride Batteries. -- The experience with the 

 silver chloride batteries apparently is not much differ- 

 ent from our experience here. The lack of any report 

 about the "B" batteries suggests that they continue in 

 good condition. 



BARBADOS, B. W. I., TO BALBOA, CANAL ZONE, OCTOBER 1 TO 11, 1928 



General. - -Observations have been made daily and 

 in as complete form as the generally variable weather 

 conditions would permit. A diurnal-variation run was 

 begun on October 8 but bad weather and a large leakage 

 in the ion counter prevented its completion. The special 

 leak tests of the ion counter suggested in Dr. Wait's 

 memorandum of September 11 were made on October 9 

 and will be found among the records being transmitted 

 from this port. 



Potential-Gradient Recorder. --This instrument has 

 operated continuously. The records, however, are 

 somewhat broken up by squalls. Reduction-factor obser- 

 vations were made at Bridgetown, Barbados and in spite 

 of indifferent weather conditions eighteen hourly values 

 are available for comparison. These give in the mean 

 a reduction factor for the ship recorder to volts per 

 meter of 0.70. This is in good agreement with the value 

 as determined at Reykjavik, which was determined in- 

 directly, by use of the reduction factor for potential-gradi- 

 ent apparatus 2 as determined at Kitt's Point. It will be 

 noticed from the summary of the observations at Bridge- 

 town that the position of the boom, rather than that of 

 the mainsail, appears to be the dominating factor, but 

 the different values are so close as to warrant using, 

 as a preliminary reduction factor, the value of 0.70 and 

 the scaled values are being converted to volts per meter 

 on this basis. The new fibers received at Barbados 

 have not been used so far but it is planned to insert one 

 set of them while docked here. 



Kolhorster Penetrating Radiation Apparatus. --On 

 October 1, 1928, after overdeflecting the fibers many 

 times, according to the advice of Dr. Kolhorster, using 

 500 voltsi, and getting no satisfactory results, we 



opened the instrument. It was found that the contactor 

 arm had been displaced to the wrong side of the contact 

 pin of the electrometer system. This condition con- 

 firmed previous impressions that the contactor arm did 

 not touch the case, as it should do, when away from the 

 contact pin. The varying deflections thus were the re- 

 sult of the varying effect of the field between the charged 

 contactor arm and the fibers, depending on changes in 

 the position of the arm, this position naturally changing 

 with the roll of the ship. When the instrument was re- 

 assembled again, a calibration was made which gave a 

 satisfactory curve, although the sensitivity had decreased 

 slightly. On October 2 and 3 observations were made 

 which gave results which were comparable with those 

 obtained with penetrating radiation apparatus 1. On 

 October 4, when about to begin an observation, we found 

 that the contactor arm had crossed to the wrong side of 

 the contact pin again. It should be mentioned that, dur- 

 ing the magnetic work on October 4, the instrument was 

 moved from the atmospheric-electric observatory to the 

 biological laboratory. The utmost care was exercised 

 in doing this and the instrument, wrapped in a soft cloth, 

 was not moved during the time it was in the biological 

 laboratory. On October 4 the instrument was reopened. 

 In trying to bend the contactor arm so as to lessen the 

 danger of its flying past the contact pin, we found that 

 the arm was loose from the amber insulator. This in- 

 sulator also holds the phosphor-bronze connector from 

 the outside terminal. This loosening probably was 

 caused by the heat softening the substance which was 

 used as an adherent. The contactor arm was removed 

 with a view to fastening it to t!ie insulator again. During 

 these operations one of the fibers became loose, at one 



