36 



OCEAN ATMOSPHERIC-ELECTRIC RESULTS 



from insulators attached to the handles of the recorder 

 box but it was found impracticable to put sufficient ten- 

 sion on the wires without deforming the rod. It will be 

 remembered that the apparatus originally was designed 

 for use with a vertical collector rod where lateral mo- 

 tion of the collector was of no importance, so this type 

 of rod was reverted to on November 5. This change, of 

 course, made a considerable change in the reduction 

 factor and thus made necessary an alteration in the 

 sensitivity of the fibers. Subsequent traces, however, 

 gave promise that a good representation of the diurnal 

 variation of the air potential could be obtained and that, 

 with adequate shore control, reliable absolute values 

 could be deduced. 



During the three days, December 9 to 11, at Easter 

 Island, intercomparisons were made between the re- 

 corder on the ship and the spare recorder mounted at 

 the shore station. In spite of very indifferent weather 

 conditions and an unfortunate fogging of the shore trace 

 during some of the daylight hours, fair provisional re- 

 duction factors for the three boom positions were ob- 

 tained, as follows: 



Mainsail up, boom starboard 1.61 



Mainsail up, boom port 1.25 



Mainsail down, boom over port crutch . . 2.48 



Between November 5, 1928 and January 14, 1929, 

 fifty complete days' traces were secured and there is 

 only one day, December 15, for which no value of poten- 

 tial-gradient is available. On this day, it should be 

 noted, no eye observations would have been possible. 



Careful attention has been given at all times to the 

 elimination of leak; tests are made daily, sometimes 

 more than once. Calibrations are made as nearly as 

 possible weekly and the curves obtained are in remark- 

 ably good agreement. 



Owing to the excessive heat generated by the burn- 

 ing lamp inside the metal-covered box, the glass window 

 has been removed. During rough weather, when spray 

 is likely to enter through the hole thus made, a plug is 

 temporarily inserted. 



Appropriate record has been kept of the positions of 

 the mainsail and boom and also the times of operationof 

 the main engine. 



A disastrous series of mishaps with fibers for the 

 recorder occurred on November 16. The fibers in use 

 were dismounted as they were obviously flaked. In at- 

 tempting to fit a new system, three pairs were broken in 

 succession. The task was then given up and the follow- 

 ing day a pair was successfully mounted and has been in 

 use since that time. The Wollaston-process gold fibers 

 were tried but were too fine and flexible for use in the 

 recorder. 



Remarkable peaks occurred in potential-gradient at 

 about 16 h on December 27. This large increase in the 

 air potential corresponded to a very low value of con- 

 ductivity obtained at that time when, fortunately, a 

 diurnal -variation run was in progress. 



Conductivity Apparatus. --On October 27, soon after 

 leaving Balboa, when preparing for observations, we 

 found that the fibers of electrometer 25 were nonconduct- 

 ing. New fibers were fitted but these also were found to 

 be flaked. A third set of fibers was mounted and, after 

 considerable adjustment for a suitable sensitivity, was 

 found to be satisfactory. This set is still In use. 



Ionic Content Apparatus. --As reported by radio, 



considerable trouble has been experienced with the 

 fibers for use with this instrument. The story can best 

 be told, perhaps, by extracts concerning this matter 

 from the atmospheric-electric log: 



Oct. 29--Adjustments to IC in p.m. Found fiber did not 

 respond to alterations of voltage as applied 

 by potentiometer. Cause unknown. Made ex- 

 haustive examination of instrument. Changed 

 fiber, with no different result. 

 30--Spent whole morning investigating IC as above. 

 Finally forced to conclusion that fiber was 

 flaked. Inserted another fiber after lunch and 

 at once got definite result. 

 31 --Adjusting sensitivity of IC between showers. 

 Began observations but fiber began to drift. 

 Spent some time investigating cause and 

 afterward made observations. 

 Nov. 1--Rain showers too frequent for any attempt to 

 be made to adjust IC. 

 2- -Adjusted IC. 

 5- -Changed fiber in IC and adjusted. Old fiber 



flaked. 

 7- -Put new fiber in IC and adjusted. Old fiber 



flaked. 

 9--Began observations but after first set IC de- 

 veloped large leak and fiber afterward be- 

 came dead." Spent remainder of afternoon 

 in adjusting, but with no result. 

 10- -Adjusted IC in a.m. ^ut in new fiber but that 

 soon flaked badly, this time in view through 

 telescope. Put in new fiber (the last good one 

 in stock) and adjusted. 

 13- -Began observations at noon. At 17h IC fiber 

 flaked badly, in view through telescope. Dis- 

 continued observations. 

 15- -Endeavored to replace IC fiber by the only 



other one on hand, that in the RCA but iiher 

 broke . 

 Dec. 1--Successfully transferred fiber from PRA to IC 

 and adjusted IC. 



This fiber is still in use. During the shore poten- 

 tial-gradient work at Easter Island, the discovery was 

 made of a single fiber in an electrometer in the instru- 

 ment room, and on December 13 this fiber was inserted 

 in the penetrating radiation apparatus where it is still 

 in use. 



We are at a loss to explain the extraordinary ease 

 with which the gold sputtering on these fibers has flaked. 

 There is no motion of the instrument in its gimbals 

 when clamped, so that the defects could not be produced 

 by continuous jarring. It would appear that those made 

 up just prior to the departure of the Carnegie from 

 Washington are, in some way, inferior to the older ones 

 but the only reason for thinking this is the fact that both 

 the single fibers now in use presumably are of an older 

 batch. All the fibers appeared perfect when inserted in 

 the instrument. One had suspicious dark patches on it 

 as it lay in the carrying box and this one was not used 

 until the last. 



Attention may be called to the observations of De- 

 cember 21 which were made while the fiber was subject 

 to a large drift. In view of the fact that all the insula- 

 tors were subjected to a thorough cleansing more than 

 once, it seems hard to believe that this drift resulted 

 from insulation leak, and it is probable that the trouble 

 was in the fiber system itself. A similar drift was 

 noted as preceding flaking on October 31 and November 

 9. It was interesting to note how well the final values 

 agreed with other data when the amount of the drift was 

 taken care of by the "leakage" corrections. 



