THE CLOUD REGION, ETC. 273 



the upper currents that are counter (Plate I.) to the trade-^inds. 

 These currents carry the clouds still farther to the north and south, 

 and thus make the cloud-rmg broader. At least we mfer such to 

 be the case, for the rains are foimd to extend out into the trade- 

 winds, and often to a considerable distance both to the north and the 

 south of the calm belt. 



524. Were this cloud-ring luminous, and could it be seen by an 

 Imagined appear- obscrver from ouc of the planets, it would present to 

 Hn*^rf,o^.[*dlsunt'^' ^^^ ^^ appcarauco not unlike the rings of Saturn 

 obJ^rver. do to US. Sucli an obscrver would remark that this 

 cloud-ring of the earth has a motion contrary to that of the axis of 

 our planet itself — that while the earth was revolving rapidly from 

 west to east, he would observe the cloud-ring to go slowly, but 

 only relatively, from east to west. As the winds which bring 

 this cloud-vapour to this region of calms rise up with it, the earth 

 is slipping from under them ; and thus the cloud-ring, though 

 really moving from west to east with the earth, goes relatively 

 slower than the earth, and would therefore appear to require a longer 

 time to complete a revolution. But, unlike the rings of Saturn 

 through the telescope, the outer sm-face, or the upper side to us, of 

 this cloud-ring would appear exceedingly jagged, rough, and uneven. 



525. The rays of the sun, playing upon this peak and then upon 

 Thunder. that of the uppcr cloud-surface, melt away one set 



of elevations and create another set of depressions. The whole 

 stratum is, it may be imagined, in the most turgid state ; it is 

 in continued throes when viewed from above ; the heat which is 

 hberated from below in the process of condensation, the currents 

 of warm air ascending from the earth, and of cool descending from 

 the sky, all, we may well conceive, tend to keep the upper cloud - 

 sm^face in a perpetual state of agitation, upheaval, and depression. 

 Imagine in such a cloud-stratum an electrical discharge to take 

 place ; the report, being caught up by the cloud-ridges above, is 

 passed from peak to peak, and repeated from valley to valley, until 

 the last echo dies away in the mutterings of the distant thunder. 

 How often do we hear the voice of the loud thunder rumbling and 

 rolling away above the cloud-surface, like the echo of artillery dis- 

 charged among the hills ! Hence we perceive or infer that the 

 clouds intercept the progress of sound, as well as of light and heat, 

 and that this upper surface is often hke Alpine regions, wliich echo 

 back and roll along with rumbling noise the mutterings of the distant 

 thunder. 



