62 Professor CErsted on TFater- Spouts . 



this takes place, must not be assumed, until the circumstances 

 observed shall give sufficient support to the idea. 



On land, the nature of the phenomenon does not easily allow 

 observers to see the beginning of the formation of the lowest 

 part of a water-spout ; and accordingly, I find no data on the 

 subject in the published descriptions. The upper part is always 

 described as proceeding as if from a thick cloud. There is 

 often remarked only a very slight increase of size of the cloud, 

 which, however, is gradually extended, and presents the 

 lengthened funnel-shaped portion. Over the sea, the upper 

 part of the water-spout has been seen to stand far from the 

 place which lay perpendicularly over the lower portion, until 

 its line of union approached more nearly to the perpendicular 

 position. 



Both on land and water, there has often been seen, in the 

 upper part of a water-spout, a thin streak of vapour which 

 seemed to sink downwards from the cloud, and afterwards 

 maintained itself in the fully developed water-spout. This is 

 most easily observed at sea, when the lower portion is gene- 

 rally transparent. Such a streak is naturally removed Irom 

 observation when the water-spout is opaque. It was remarked 

 on one occasion, that it became visible while a land water- 

 spout was crossing a river. 



We can hardly assume that the top of the water-spout is at 

 that point, where, to the inattentive eye, it appears to lose 

 itself in the clouds. Shortly before the appearance of that 

 Avater-spout which occurred in the neighbourhood of Eu, it was 

 observed that the clouds separated, and that some went in an 

 opposite direction from the rest, a fact which seemed to indi- 

 cate a consequent turning round. A careful observer, Holm, 

 remarked during a water-spout near Copenhagen, through 

 the openings in the lower strata of clouds, a rotatory move- 

 ment in those lying above. From the upper portion of the 

 water-spout, there proceeded white clouds which had a whirl- 

 ing motion like ^he water-spout itself. 



When the dissolution of the water-spout approaches, the 

 middle portion, especially that part nearest the earth, becomes 

 more and more transparent. The water-spout generally 

 breaks up in the middle. The upper portion shrinks and dis- 



