FLOW OF THE KIYER TEVIOT. 187 



the common laws of heat and cold influence its freezing, and deep water 

 never congeals until the whole mass is brought to the freezing point. In 

 our most northern settlements, Hudson's Bay for instance, stagnant water 

 is known to freeze to the depth of ten or twelve feet, and all the fish are 

 fi'ozen along with it : — not so in the rivers — the surface is frozen indeed, 

 but the ice thenbecomes a protection to the running water beneath^ from 

 the greater cold of the atmosphere. It is quite evident that in all run- 

 ning streams, the falling down of the colder, and the rising of the 

 warmer water cannot take place with any uniformity, for the movements 

 of the current prevent the regular action of heat and cold, and the 

 discharge of the springs into the channel of the river from a greater 

 depth than the frost penetrates, keeps the water still moving freely 

 below the surface of the ice. 



To explain the singular phenomenon of the stoppage of mountain 

 streams, it is necessary to consider how they usually flow. Where rocks 

 abound and the channel is alluvial gravel, every one, conversant with 

 Highland scenery, is aware how the rivulet meanders almost in circles, 

 forms a succession of streams and pools, and at every turn creates a 

 natural weir, extending from side to side at oblique angles. The pools 

 discharge themselves at their lower extremity, over these natural weirs, 

 which again forms the head of the streams below, and the streams 

 again terminate in pools, and so on in succession, till the enlargement 

 of the stream renders the natural weir less observable. 



Let the wind come from any point of the compass, it must blow 

 directly in the face of a great number of these banks of sand and 

 gravel, will stop the descent of floating ice, and materially assist in 

 freezing it into a more solid mass. It will make the stoppage more 

 easy in the natural weirs below, by diminishing the current of water 

 until it ceases to flow altogether. To produce this, it is possible that 

 frost alone may be sufficient, but to do it more effectually, wind in 

 addition wovdd appear to be requisite. Now this actually was the 

 case during the night of November 26-7. The phenomenon which 

 occurred at Ormiston cauld shews, in a remarkable manner, how far 

 the effect may be carried ; but the stoppage of the rivers must be 

 sought for in the natural weirs, where the frost, fixing on the shallow 

 bottom, forms a ground-ice, and then catching the light floating grew, 

 makes a chain of obstructions, while the stream being stopped, there 

 is time for the ice to form a covering on the surface of the pools. After 

 a time, which will be longer or shorter according to circumstances, the 

 springs will force these barriers, and the flowing water will resume its 

 course. If there is a tendency to fresh weather, the stream will be 

 increased in volume according to the duration of the previous stoppage, 

 as was the case on the afternoon of November 27. and the following 

 day, in the Kale and the Teviot. If the frost continues, the waters 

 again flow beneath the ice, although ciit off from any other supply 

 than what the natural channel of the hrook receives from the springs 



