A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



ported on hard rvibbcr insulators, i, i, about 15 cm. long, and at a distance of 

 10 cm. from the end of the tube. This rod is highly charged from the storage 

 battery, B, and the leakage found from the electrometer, E, one pair of quad- 

 rants of which are in connection with r, r, and the other pair put to earth. A 

 commutator enables the observer to use either the positive or the negative pole 

 of the storage battery for charging the s^'stem. 



Figure 2. — Modification of Preceding Apparatus with Side Influx Tube, k, f, n, for Maintain- 

 ing Constant Pressure in .4, and Removable Desiccator, D. 



The electrometer was specially built for the present purj')oses, and the 

 needle was kept charged by a water battery of 48 volts, one pole of which was 

 earthed. The suspension is a silk bifilar moistened by a dilute solution of any 

 hygroscopic salt, and the battery charge is conveyed through the fibers. The 

 quadrants are supported on hard loibber insulators 10 cm. long. Difficulties 

 were encountered in using this apparatus as will appear below. In figure 2 a 

 side tube, /, between stopcocks k and n has been added, with the object of secur- 

 ing greater constancy of pressure in A, the flow of water from M being via m f n. 



7. Mampulaiions. — On raising the Mariotte flask, M, and opening ap- 

 propriate stopcocks, the emanation passes directly from the ionizer into the 

 condenser, and its ionization may fie measured. A tower desiccator is here 

 to be inserted before P, to dry the air. 



On lowering M, removing D, and reversing P, the emanation passes into 

 A. Here its nucleation may be tested by condensation, and it may thereafter 

 be introduced into C at once or after a number of condensations. The nucleation 

 may also be stored in a dry vessel between D and P reversed, and subsequently 

 transferred from the dry vessel into the condenser. 



Finally, the phosphorus ionizer P and D may be quite removed and re- 

 placed with a pipe connection, while the tube nj is adjusted for spraying. The 



