38 



OCEAN ATMOSPHERIC-ELECTRIC RESULTS 



and the apparatus as now arranged, it is possible for the 

 complete hourly cycle of observations to be made by one 

 observer. 



Potential-Gradient Recorder. --During the first few 

 days after leaving Callao on February 5, parts of three 

 days' records were lost because the loose end of the ten- 

 sion string (which prevents too rapid feeding of photo- 

 graphic paper and which had been renewed recently) 

 became caught on the lower tension roller and stopped 

 the supply of paper. From February 15 to March 5 in- 

 clusive, continuous record of potential-gradient was ob- 

 tained. After March 5, when the ship was among the 

 island groups, generally squally conditions prevailed; 

 light, variable breezes and frequent calms at times ne- 

 cessitated the operation of the main engine. Conse- 

 quently the records are intermittent; in fact, only one 

 Greenwich mean day, March 25, is really complete be- 

 tween March 6 and April 2. Part of this loss, it should 

 be noted, was caused by instrumental difficulties. The 

 upper heating coil became open-circuited and caused 

 loss of zero marks until it was replaced by a new one. 

 Also, on March 26 the earthing wire became corroded 

 and disconnected from the hull and caused erratic de- 

 flections until it was discovered and renewed on March 

 28. 



In order t-> shelter the helmsman from the fierce 

 tropical sun, frequently it has been necessary to stretch 

 an awning over the stern. Thus, the reduction-factor 

 observations contemplated at Apia will be extended so as 

 to include periods with stern awning "up" and "down" 

 to determine the effect, if any, of its presence. 



Conductivity Apparatus 8A. --Thls apparatus has 

 functioned normally throughout. 



Ionic Content Apparatus I .--N0 trouble, apart from 

 the usual insulation difficulties, has been experienced 

 with this apparatus. A cover for the top of the air -flow 

 tube has been made so that the cowl can be removed 

 when the roof opening is closed, thus minimizing the 

 chances of jarring the tube. 



Penetrating Radiation Apparatus 1 . - -During the 

 early part of February there were indications that the 

 values of R that were being obtained were not independ- 

 ent of fiber sensitivity. With a low sensitivity the values 

 of R tended to be greater than those with a high sensitiv- 

 ity. The truth of this suspicion naturally was not very 

 obvious in the daily observations but for the diurnal- 

 variation run of February 10 and H, when the scale- 

 value curve was plotted and compared with the curve for 

 the values of R and a remarkable similarity was dis- 

 closed, a definite relation was demonstrated. 



During the diurnal-variation observations of Febru- 

 ary 18 and 19 the electrometer fiber went off scale and 

 attached itself to one of the plates. Afterwards it was 

 found that this action occurred because one of the cells 

 of the plate battery had developed a high internal resist- 

 ance. During efforts to release the fiber from the plate. 

 It was broken. Later in the same day the defective cell 

 was replaced by a new one and a new fiber was inserted 

 in the electrometer. Tests were made to determine 

 whether a change in scale value produced a change in R. 

 It was found that the two values were independent of one 

 another. With the diurnal-variation curve of February 

 26 and 27 also has been plotted the scale -value curve 

 and here, again, the independence is well demonstrated. 



The sodium in the drying tul)es was renewed on 

 March 27, the usual precautions being taken. 



Penetrating Radiation Apparatus No. 5503. - -This | 



apparatus was received on board at Papeete, Tahiti, on 

 March 16, 1929 after having been overhauled and recon- 

 ditioned in Washington. When the apparatus was un- 

 packed, the Zamlwni pile, which presumably had been 

 screwed on to the charging post before shipment, was 

 hanging loose. The outer threads on the pile were 

 stripped badly enough to prevent its being replaced on 

 the charging post. Beyond securing the instrument in its 

 former situation on the observing bench, between the 

 penetrating radiation apparatus 1 and radioactive con- 

 tent 4 and covering the charging post with the cap pro- 

 vided, nothing further was done to the instrument until 

 March 21, after leaving Papeete. On attempting to apply 

 a charge to the fibers, it was found that the charging arm 

 was on the wrong side of the standard pin. Efforts made 

 to put it back on the right side by sudden movements of 

 the magnet were unavailing and therefore it was reluc- 

 tantly decided to open up the case. This was done on 

 March 21. Other than carefully lifting the pointer past 

 the pin, nothing inside the case was touched and the 

 time the case was open on this occasion did not exceed 

 30 seconds. On resealing the case, and applying a 

 charge to the fibers, it was apparent at once that the 

 fibers were adhering, either to each other, or to the 

 spines, or were crossed. The separation of the fibers 

 at the bottom of the field of view was much greater than 

 at the scale level, whereas at the top of the field the 

 fibers were very close together and out of focus. In 

 order to separate the fibers, a charge of over 460 volts 

 (10 "b" batteries in series) was applied many times, 

 the fibers being charged and earthed in quick succession. 

 This charge would, of course, normally send the fibers 

 right off scale but the total deflection of both fibers was 

 not more than sixty divisions. An hour or more was 

 spent in this way and further efforts in the same direc- 

 tion were made on March 22, but with no success. On 

 March 23 it was decided to reopen the case and separate 

 the fibers by passing a glass spine between them. This 

 operation, a delicate one under the best conditions, was 

 rendered more hazardous by the rolling of the ship in a 

 moderate swell and also by the intense heat in the at- 

 mospheric-electric laboratory with door and all windows 

 closed to prevent draughts. The separation was accom- 

 plished successfully at the first attempt, however, and 

 the instrument resealed. Two trial observations made 

 later in the day gave high values. Doubtless this can be 

 attributed to a slight leak over the quartz rod, rendered 

 damp by exposure; subsequent observations showed that 

 the sodium in the drying tubes was gradually restoring 

 the insulation. 



Control observations on the quarter-deck to deter- 

 mine the reduction factor of penetration radiation appa- 

 ratus 1 will be made as soon as possible, probably while 

 the vessel is anchored at Apia. 



Radioactive Content Apparatus 4. - -Considerable 

 time was spent between March 4 and 9 in trying to get 

 this apparatus to function normally. On March 4 most 

 of the parts were disassembled and cleaned. On reas- 

 sembling, a potential of over 2700 volts was maintained 

 for over thirty minutes and accordingly a fiber was in- 

 serted in the electrometer (the original fiber was broken 

 on November 15, 1928 in an endeavor to place it in the 

 penetrating radiation apparatus) and adjusted in readi- 

 ness for a regular observation the next day. On March 

 5, however, when the inner cylinder with the foil was in 

 place, no potential at all could be obtained. It was sus- 

 pected that the lower end cover which, of course, is 



