III. REPORTS ON ATMOSPHERIC-ELECTRIC WORK OF CRUISE VII, 1928-1929, 



PREPARED ON BOARD SHIP 



NEWPORT NEWS, VIRGINIA TO PLYMOUTH, ENGLAND, MAY 10 TO JUNE 8, 1928 



After leaving Newport News on May 10 the first few 

 days were occupied in acquiring some degree of facility 

 in observing during the ship's motion. The conductivity 

 and penetrating radiation apparatuses have presented no 

 great difficulties but the ion counter has been found to 

 be extremely sensitive to rolling and the fiber therefore 

 hardly ever at rest. It might be considered advisable to 

 increase its stability by having an additional weight be- 

 low the electrometer platform which could be removed 

 when the gimbals are clamped, thus preventing undue 

 wear on the pivots. 



A systematic daily program of observation similar 

 to that carried out on previous cruises has not been ar- 

 ranged, for the following reasons. During the oceano- 

 graphic work the potential-gradient at the stern cannot 

 be observed, because the engine is running and nets are 

 being towed; also, with the ship hove to, the rolling is 

 excessive and we have not been able to work with the ion 

 counter at these times. When the magnetic work is be- 

 ing done, the conductivity motor possibly may cause 

 disturbances in the field in the after dome. The oceano- 

 graphic work and, to a lesser degree the magnetic work, 

 are controlled by sea conditions and it has happened on 

 one occasion so far that the oceanographic work has 

 been done in the morning and the magnetic work in the 

 afternoon of the same day, leaving no part of the day 

 free for atmospheric-electric work. It is proposed to 

 make tests to determine the effect, if any, of the con- 

 ductivity motor on the magnetic work in the after dome 

 and a regular schedule of atmospheric -electric obser- 

 vations will be carried out as often as conditions permit. 



Recording Potential-Gradient Apparatus. --Contin- 

 uous recording of potential- gradient at the masthead 

 has had to be discontinued. For the first few days, while 

 the mainsail was to port, the recorder box remained 

 fairly steady and one good 24-hour trace was obtained; 

 the fibers, however, were at a low sensitivity (about 60 

 volts per division). When the mainsail was put to star- 

 board, the recorder-box guide cables slackened, owing 

 to the play in the masthead and the box was in continuous 

 motion through an angle of about 45° astern of the mast- 

 head. The traces obtained during this period were quite 



illegible. There is no way of preventing this play of the 

 masthead because of the elasticity in the hemp rigging. 

 There were diffictilties in raising and lowering the box 

 past the sail when the mainsail was to starboard also. 

 Then it was thought that a satisfactory diurnal-variation 

 curve might be obtained on the roof of the atmospheric- 

 electric house, in spite of the probable low field due to 

 the proximity of the mainmast and staysails. An experi- 

 mental trace, however, showed that the field was too 

 weak to produce a curve from which the diurnal varia- 

 tion might safely be derived. Next it is planned to try 

 mounting the box on the stern rail, near potential gradi- 

 ent apparatus 2, though it is feared that the daily running 

 of the engine will produce serious gaps in the records. 



Radioactive Content Apparatus. --On several occa- 

 sions during the few periods of good weather we have 

 had, we have experimented with the collector of this 

 apparatus but have been unable, so far, to maintain a 

 potential of 1500 to 2000 volts for more than five min- 

 utes. For a time it seemed that it was an advantage to 

 have the door closed rather than open, but in the end the 

 insulation always broke down after a few moments had 

 elapsed. We have been unable so far, therefore, to ob- 

 tain any observations of radioactive content, but experi- 

 ment with the collector will be continued as soon as 

 possible. 



Diurnal- Variation Observations. --Persistent bad 

 weather has prevented diurnal-variation observations of 

 any of the atmospheric-electric elements. 



Nuclei Concentration. --Since May 21 practically 

 daily observation has been made with the nuclei counter 

 4. No difficulties have been encountered. 



Batterv Replacements. --Fifteen cell replacements 

 have been made in battery 14689 and the use of the bat- 

 tery on June 7 for calibration of potential gradient appa- 

 ratus 2 indicated some more bad cells. All other bat- 

 teries have maintained high potentials. 



Attention might be called to the consistently low 

 values that were obtained for ionic content and conductiv- 

 ity, particularly the latter. No reason for this fact is 

 apparent, except unusually stormy weather conditions. 



HAMBURG, GERMANY TO REYKJAVIK, ICELAND, JULY 7 TO 20, 1928 



General . - -Observations of all the atmospheric- 

 electric elements, with the exception of radioactive con- 

 tent, have been made whenever conditions permitted. 

 Lack of time and adverse weather have prevented any 

 attempt to get the radioactive content apparatus into 

 working order. It is hoped that something may be done 

 with this when more temperate latitudes are reached. 

 During the stay in Hamburg additional shelf space was 

 provided in the atmospheric-electric observatory for the 

 storage of batteries and miscellaneous equipment. 



Potential Gradient Recorder. --At Hamburg a staging 

 was built on the stern rail, to starboard of the potential- 

 gradient apparatus 2, and the recorder was mounted 

 thereon. The collector rod was remodeled so as to al- 



low the disc collectors to project over the stern. So far 

 some very good traces have been obtained with this 

 arrangement. Because head winds required frequent 

 running of the main engine, some of the records do not 

 represent normal air conditions. Appropriate record, 

 of course, will be kept of the times of starting and stop- 

 ing the main engine, for proper interpretation of the 

 traces. It was hoped that the traces obtained up to date 

 might have been transmitted before leaving Iceland but 

 the ship and shore observations have made this impos- 

 sible. It is felt, however, that the present location of 

 the instrument is the only feasible one on the ship and it 

 is confidently anticipated that some reliable diurnal- 

 variation data will be obtained. 



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