Running Streams during periods of Frost. 225 



of some ground ice examined in a small rivulet 12 miles 

 north of Liverpool ; at the same time I described the rapid 

 formation of numberless small ice pillars I had witnessed 

 on the sides of the Pentland hills near Edinburgh, after a 

 single night's frost, from the water oozing gradually to the 

 surface as it descended the hill. Captain Scorseby, in vol. 48, 

 p. 1, of this Journal, has given a similar description of ice 

 pillars formed under like circumstances. And I find in con- 

 versing with those resident in hilly districts, that they are 

 familiar with them. Around Liverpool, in delfs, I have often 

 noted, during periods of frost, large accumulations of ice on 

 the wall- sided surfaces of the sandstone which bound these 

 delfs ; where the conditions for freezing are not favourable ; 

 the walls being vertical and very confined, screen the parts, 

 from radiation to the open sky. Yet, in confined situations, 

 where the water oozes slowly to the surface, masses of ice 

 collect which much exceed in thickness that on the adjacent 

 ponds open to the sky and winds. While on a recent journey 

 among the hills of Westmoreland, Dumfries and Lanark 

 shires, I saw masses of ice formed from the water coming 

 slowly to the atmosphere, where it spreads over the surface 

 of the ice already made in a thin film, so as to be very favour- 

 ably placed for freezing. This water which oozes to the 

 surface on the rocks and hillsides forms a chief source of 

 supply of the rivulet, which, in a hilly country every valley 

 has ; presently these rivulets are joined together to make a 

 river which is hastening to the sea. In such districts, then, 

 the sources of streams are extremely active in ice-making, 

 and the water in its passage downwards has to bathe a large 

 superficies of this material, which it must continue to melt 

 until the stream is cooled down to a freezing temperature ; 

 a process which appears to go on with celerity after frosty 

 weather has formed ice on the surface of the quieter parts 

 of a running stream. 



During frost, a walk along the bank of a river shews in 

 various ways how the current of a stream acts favourably for 

 forming ice. The water in rivers is usually then low for 

 the winter season ; the action of the frost checking the sup- 

 ply. The stream occupies only a portion of its bed — ice 



