A Waterspout. 343 



One of the most interesting phenomena in connec- 

 tion with the weather seems to me to be the nidiation 

 of clouds. It appears to be more commonly- visible 

 in the evening, and, when fully develojjed, there is a 

 low bank on the horizon, roughly arched, from which 

 streamers of cloud trail right across the sky, through 

 the zenith and down to the horizon opposite. Near 

 each horizon these streamers or lines almost touch ; 

 overhead they are wider apart — an effect of perspec- 

 tive, I suppose. Often the lines do not stretch so 

 far, hardly to the zenith, where they spread out like 

 a fan. If the sun has gone down, and the cloud 

 chances to be white, these lines greatly resemble the 

 aurora borealis, which takes the same form, and, 

 when pale, can scarcely be distinguished from them, 

 except for the streamers shooting — now extending, 

 now withdrawing — while the cloud streamers only 

 drift slowly. Sometimes there is but one line of 

 cloud, a single streamer stretching right across the 

 sk}'. So far as I have been able to observe, this 

 radiation is usually followed by wind blowing in a 

 direction parallel to the course of the streamers. 



Once while walking in winter I was overtaken by 

 a storm of rain, and took shelter behind a tree, M'hich 

 for some time kept me perfectly dry. But suddenly 

 there' came an increase of darkness, and glancing 

 round, I saw a black cloud advancing in the teeth of 

 the wind, and close to the earth. The trees it passed 

 were instantly blotted out, and as it approached I 

 could see that in the centre it bulged and hung down 

 — or rather slightly slanting forward — in the shape of 

 an inverted cone with the apex cut off". This bulging 

 part was of a slaty black, and the end travelled over 



