REPORT ON ATMOSPHERIC ELECTRIC WORK 



39 



earthed, was touching the foil. With this cover removed 

 and, indeed, without any inner cylinder, the potential 

 on the following day could not be maintained for more 

 than two or three minutes. Trouble was then experi- 

 enced with the atomizer which became clogged; so it 

 and also the water vessel, were thoroughly cleaned, 

 freshclear water was provided, and new rubber tubing fit- 

 ted. On March 8 cardboard covers were made and fitted 

 over the main insulators and some of the wiring was 

 renewed. (It appeared to make no difference whether 

 the hard rublier insulator on the 110-volt power line was 

 covered or not.) With the main insulator covered, the 

 potential obtained never exceeded 1000 volts, probably 

 owing to the added capacity, but could be maintained, at 

 first, for a considerable time, say fifteen to twenty min- 

 utes. Later this time became reduced to anything be- 

 tween one and three minutes, the same as without the 

 cover. The most obvious explanation of the difficulty is 

 the fouling of the insulators by the spray. But a curious 

 fact is the ease with which the charge will rebuild just a 

 few seconds after it has been reduced to zero. This 

 gives one the impression of a short circuit which oper- 

 ates only when the vessel is highly charged, the contact 

 being broken at zero potential. Careful search has been 

 made to discover any lint or other material attached to 

 any of the parts, which might act in this way, but noth- 

 ing has been discovered. The use of a shield to cover 

 the whole system appears well worth trying. It is doubt- 

 ful whether such a shield could be made satisfactorily 

 on board or at any of the ports earlier than San Fran- 

 cisco; therefore it would be best, perhaps, to have it 

 made in Washington and shipped to us. 



Nuclei Counter 5. --This instrument was obtained 

 from the equipment of the Huancayo Observatory while 

 the ship was in Callao harbor to replace no. 4, which 

 was returned to Washington. After some slight prelim- 

 inary adjustment, no difficulty was experienced in its 

 use. During the approach to Tahiti rather large values 

 of nuclei concentration were obtained; after leaving 

 Tahiti there were frequent rain storms and the number 

 of nuclear particles decreased considerably. 



Comments 



General. — Although a succession of squalls, calms, 

 and periods of heavy rolling in swells interfered con- 

 siderably with the atmospheric-electric observations in 

 the latter part of this leg of cruise VH, considerable 

 was accomplished in the earlier part. In a careful ex- 

 amination of the records, one is favorably impressed 

 with the progress being made and especially with the 

 dUigeiice and skill of the observer and the excellent 

 form in which the records are made up. The observa- 

 tions of the diurnal variation of nuclei concentration are 

 commendable. A study of the correlation of this ele- 

 ment with the ionic number during the day will be of 

 great importance and will be made when the number of 

 series is sufficient to give hopes of definite results. 



Potential-Gradient. --The various instrumental dif- 

 ficulties with the potential-gradient recorder are all 

 such as must be expected occasionally. No doubt the 

 earthing connection which failed will be inspected in the 

 future whenever the opportxmity occurs so that this may 

 be renewed in time to lessen the likelihood of failure on 

 the high seas. The effect of the stern awning should not 

 be very large but of course it is quite right to eliminate 

 this possibility by ascertaining a reduction factor for 



use when this awning is in position. B is noted that ob- 

 servations on potential-gradient apparatus 1 are no longer 

 being made. Such observations should be helpful as a test 

 of the effectiveness of the insulation on the recorder. 



Conductivitv Apparatus 8A. --It is gratifying to note 

 that the insulation-leak on this apparatus scarcely 

 exceeds the error of an electrometer reading. This 

 constitutes a great improvement in comparison with the 

 apparatus of previous cruises. As far as noted, the in- 

 dication of leak, when found, was always on the first 

 reading. Can the observer suggest an explanation for 

 this? 



Ionic Content Apparatus l .--The cover which was 

 made for the air -flow tube of the ionic content apparatus 

 should assist also in protecting the insulation during the 

 period when the apparatus is not in use. Some evidence 

 that extreme values of ion count give extreme values of 

 mobility has been noted. Some of these cases may be 

 owing to accidental errors of observation, but there may 

 be other fartors, for example meteorological ones, 

 which careful scrutiny will disclose. 



Penetrating Apparatus l.- -The indication that the 

 values of R varied with the electrometer sensitivity 

 would appear, as reported, to have been associated with 

 the defective cell. Just how the defective cell caused 

 this and also how it should cause the fiber to go off scale 

 so as to adhere to the plates is not clear at present, un- 

 less the balancing condenser should be out of balance or 

 imless the insulation at some point on the battery lines 

 was defective. Of course if the megohm resistor should 

 develop an open circuit either in its coils or at a binding- 

 post connection, that of itself could cause such effects. 

 Whatever the explanation is, it is gratifying that later 

 comparisons gave no further evidence of a dependence 

 of R on electrometer sensitivity. Studies of possibilities 

 of instrumental errors such as these are very desirable 

 even if it is necessary to omit an occasional daily pro- 

 gram. Instruments are not infallible and it is highly de- 

 sirable to ascertain for each instrument its degree of 

 fallibility. Especially is this true of the penetrating 

 radiation apparatuses. 



Penetrating Radiation Apparatus No. 5503. - -The 

 difficulties experienced with penetrating radiation appa- 

 ratus no. 5503 are to be regretted. No doubt the fiber 

 loops would have been in good shape had the Zamboni 

 pile not worked loose. The difficulty with the charging 

 arm could not have been so readily avoided. If the 

 standard pin of the electrometer element had been made 

 long enough to prevent this sort of occurrence during 

 shipment, that would have increased the capacitance 

 considerably and consequently decreased the quantity 

 sensitivity of the instrument. Under the circumstances 

 it was quite the proper thing to open the chamber and 

 correct the defects. Mr. Parkinson is to be congratu- 

 lated on the successful outcome. It is noticed that the 

 calibration curves do not differ much from those ob- 

 tained before this instrument was shipped from the of- 

 fice. It is hoped that no further difficulties will be ex- 

 perienced with this apparatus. 



An examination of the observations from March 23 

 to April 1, inclusive, shows that this instrument has suf- 

 fered no air leak of importance. The test for this is that 

 the pressure (p) in the chamber, divided by the absolute 

 temperature (273 plus observed temperature, t), should 

 be constant if the chamber is airtight. Thus 



p/(273 + t)=K 



