WATER-SPOUTS ON THE COAST OF N. S. WALES. 139 



to keep down the heated air which was all the time trying to rise. 

 Now and then some little vortex in the overhead current gave the 

 lower heated air a chance to screw its way upwards and through 

 the overhead current; this vent once established is maintained by 

 the great extent of heated air on the earth's surface, all of which 

 is seeking an opportunity to rise. Sometimes ten or more are all 

 going on at the same time, and they travel slowly eastward. They 

 never exhibit any great energy, just enough to carry up fine dust 

 in a spiral two or three feet in diameter. The air is very dry and 

 uniformly heated, and the increase of the ascentional force by 

 the condensation of moisture as it rises, which, as we shall presently 

 see, is such a powerful factor in the formation of a water-spout is 

 altogether wanting in sand spirals. 



A WATER-SPOUT VIEWED FROM ABOVE AND BELOW. 



M. Kaemtz, the late able Meteorologist, in his work on Meteor- 

 ology, says, page 393 : "I was on the Rigi, and looking down I 

 examined masses of fog preceding towards each other in the valley 

 of Gulden, whilst around me, as I stood on the mountain, the air 

 was calm and the sky serene. At the end of a few moments the 

 masses of cloud united, and I observed a gyrating movement in 

 the midst of them ; the fog then extended upwards with incon- 

 ceivable rapidity, and violent gusts of wind drew from it hail and 

 rain. In the meantime the temperature had fallen, so that the 

 water in the teeth of my anemometer was congealed. A friend 

 of mine, who arrived in the evening, told me that ' on the Lake 

 of Quartre Cantons he had experienced a violent storm, during 

 which the clouds were driven in different directions, and at the 

 same time he saw a water-spout.'" Kaemtz calls particular atten- 

 tion to the inconceivably rapid extension of the fog about him, 

 due no doubt to the moisture-laden air carried up by the water- 

 spout below, which expanding by relief of pressure as it rose 

 higher and higher on the mountain, and at the same time affected 

 by the cold of these regions, would of necessity deposit much of 

 its moisture as fog. This conversion of the water-vapour into 

 particles of water, i.e. fog, would increase the partial vacuum and 



