Running Streams daring periods of Frost. 227 



the action of the current ; in the stream near Liverpool this 

 gray colour results after the ice has been for a few days 

 under water. 



Joppa rivulet, where it passes underneath the turnpike 

 road, about a mile beyond Portobello, and immediately before 

 it enters the estuary of the Forth — temperature 32°. The 

 road is carried over this stream by a low stone arch, and the 

 situation is one of the last where ice would be expected to 

 be formed by atmospheric influence ; the surface of the 

 stream generally was covered with surface-ice ; under the 

 arch at the edges there were a few crystals, but the breadth 

 of the surface of the stream was there clear of ice. In the 

 bed, eight to ten inches under water, there was a plentiful 

 crop of ice composed of small crystals interlaced with one 

 another like snow, and of a pure beautiful hue ; this lodge- 

 ment extended over the whole of the bed under the archway 

 where the nature of the ground and rapidity of the current 

 favoured the accumulation, and for so small a stream shewed 

 as fine a specimen of ground-ice, and the phenomena attend- 

 ing its formation, as could be desired. That it was brought 

 down by the current from higher parts of the stream and 

 lodged there could not be doubted, and it owed its preserva- 

 tion in such a locality to a current of ice-cold water continu- 

 ally playing upon it. 



The Esk, at Musselburgh — temperature 32°. This stream 

 must quite recently have reached the freezing temperature, 

 for ground-ice was sparingly found in its bed, only in places 

 where the current was rapid, and many of the plants in the 

 bed in favourable enough situations had not yet received any 

 ice. The river occupied a portion of its channel ; in some 

 localities ice gathering and blocking up a passage between 

 two stones had diverted a part of the water into another 

 part of the bed. 



The Water of Leith, near a village of the same name, and 

 at Saughton Hall, was examined — temperature in both in- 

 stances 32°, with ground-ice under the arches of the bridges 

 and other places favourable for its lodgement, but, like the 

 Esk, the crop was not abundant. 



A small rivulet which crosses the road that leads from Cor- 



