A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



35 



metallic supports are capable of sliding to and fro in the base plate and of being 

 clamped in any position. Influx of nuclei occurs at 5. To change C, the sleeves 

 // are loosened and the rod rr removed, after which the tube C may be slid off 

 and another inserted. Set screws and clamp screws complete the adjustment 

 as shown in the figure. 



Table 17 shows the results in which the insulation of the condenser was 

 determined before and after each measurement with the nucleated medium. 

 The condenser lengths, 60 and 15 cms., are inserted as a sufficient contrast. 



TABLE 17.— EFFECT OF LENGTH OF TUBULAR CONDENSER. dV/dt= i.g LIT./ 

 MIN. ^=3.5 VOLTS/cm. (7 = 409/9 X 10- FARADS. 



* During the passage of nucleated air through condenser. 



It is seen that the currents are certainly quite as large, ccet. par., when the 

 length of the tube condenser is 1 5 as when it is 60 cm. It is actually larger at 

 15 cms., due to the gi-adual enlargement of the needle holes' in the lead jet, 

 whereby fresher nuclei are conveyed into the condenser. The currents for 

 positive and for negative charges have the usual relation to each other. 



The table shows another interesting fact, already pointed out above, that 

 the current, ds/dt (per min.), increases as the water level in the receiver rises, 

 or as the discharge into the condenser is fresher. One naturally inquires what 

 the maximum charge of each nucleus would be if there were no conveyance tube. 



1 The fine holes clog with lead hydrate when the jet is left standing in a damp atmosphere, 

 and the obstruction is gradually removed by the friction of the water. Old jets long unused 

 therefore show small electrical currents as compared with new jets. 



