THE EQUATORIAL CLOUD-RING. 219 



we may well conceive, tend to keep the upper cloud-surface in a 

 perpetual state of agitation, upheaval, and depression. 



608. 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 thun- 

 der. How often do we hear the voice of the loud thunder rum- 

 bling aild rolling away above the cloud-surface, like the echo of 

 artillery discharged among the hills ! 



609. Hence we perceive or infer that the clouds intercept the 

 progress of sound, as well as of light and heat, through the atmos- 

 phere, and that this upper surface is often like Alpine regions, 

 which echo back and roll along with rumbling noise the mutter- 

 ings of the distant thunder. 



610. It is by trains of reasoning like this that we are continu- 

 ally reminded of the interest which attaches to the observations 

 which the mariner is called on to make. There is no expression 

 uttered by nature which is unworthy of our most attentive consid- 

 eration — for no physical fact is too bald for observation — and mar- 

 iners, by registering in their logs the kind of lightning, whether 

 sheet, forked, or streaked, and the kind of thunder, whether roll- 

 ing, muttering, or sharp, may be furnishing facts which will throw 

 much light on the features and character of the clouds in different 

 latitudes and seasons. Physical facts are the language of Nature, 

 and every expression uttered by her is worthy of our most atten- 

 tive consideration, for it is the voice of Wisdom. 



