voith the Condensation of Vapour, 167 



immediately below it electrified negatively^ the depth of this 

 stratum depending upon the thickness or density of the bed 

 of haze above; and 3rd, the lowest stratum possessing the 

 usual positive charge of the atmosphere. It is in this lower 

 stratum that Mr. Howard considers the cumuloid masses 

 to be formed; and while the negative stratum remains sus- 

 pended between the superior and inferior positively electrified 

 strata, the only result is a simple union of the cumulus below 

 with the cirrostratus above, forming the compound modifica- 

 tion cumulostratus. During this process no rain Jails; the 

 reason Mr. Howard appears to regard as the absence of a 

 transmission of the electric force ; for he says, " The effect of the 

 superinducing charge on such cloud may produce either the 

 CUMULOSTRATUS, which appears to be a simple union of 

 clouds, or the nimbus, which is a union with transmission 

 of electricity." And it further appears from Mr. Howard's 

 remarks, that while a stratum positively charged is interposed 

 between the earth and the negative stratum, raiii is not pro- 

 duced; but the moment the negative stratum reaches the earth, 

 and the cumuloid masses are enveloped and lose their positive 

 charge in it, " they then attract and are attracted by the po- 

 sitive haze (query cirrostratus) above, and the first drops of 

 rain are \thus^ formed " the cloud produced being a nimbus. 

 *' This rain opens an immediate communication with the earth ; 

 the positive electricity, which before rendered the particles 

 buoyant, streams down along with the rain and through 

 it; and the shower is propagated in all directions till the whole 

 mass of cloud is brought into action." It is worthy of remark, 

 that generally before a shower an atmospherical conductor 

 indicates the presence of negative electricity. 



Mr. Howard appears to view the mode in which rain con- 

 ducts electricity to the earth under two aspects: — 1st. " The 

 individual drops may receive an intense charge at the moment 

 of their formation and during their fall through the cloud, 

 which charge they bring to the ground." Throughout the 

 whole of Mr. Howard's reasoning, the great increase of ten- 

 sion consequent on the increase in the size of the drops from the 

 agglomeration of the minute particles of water separated by 

 condensation is very prominent. Under ordinary circum- 

 stances the intense charge of each drop is brought to the 

 ground ; but if the quantity of electricity is increased in a 

 greater proportion than the surface of each drop over which 

 it is spread, then in the very act of descending to the earth 

 the tension may be so far increased that the electric force 

 may separate from each drop, to seek either the surface of the 

 cloud or of the newly-formed descending body of rain, and 



