Waters in the Estuaries of the Mersey and Clyde. 109^ 



The highest temperature of the water of the Mersey was 

 observed on 21st June, when it reached 69° ; for some days 

 it slowly approached this temperature, while the air in the 

 shade was varying, at the hour of its maximum, from 78° to 

 80°, with little or no wind. On the 24th June, with a mo- 

 derate WNW. wind, the water had fallen to QQQ^ shewing 

 a rate of change of 0*8 per day from the maximum summer 

 heat. When the spring-winter of 1845 broke up, towards 

 the end of March, the rate of change was 1° per day, which 

 must be looked on as quite the extreme ; for through the 

 sultry weather of the past summer, I have had good oppor- 

 tunities of observing the rates of change of temperature, 

 which, for several days taken together, often came near 0*8 

 per day, but never exceeded that quantity. In the green- 

 coloured and more transparent water of the Irish sea, out- 

 side the estuary, the temperature was 63° at the time that 

 the tidal waters which pass and repass before the dock-wall 

 of the port were 69°. In the fresh-water ponds in fields 

 around Liverpool, a similar difference existed between those 

 shaded by foliage and those open to the sky, — the shaded 

 ones corresponding in temperature to the waters outside of 

 the estuary, the open ponds to the water among the banks. 



In the Clyde, nearly opposite the entrance to Loch Long, on 



30th June, the temperature was . 54*5 



6th July ... ... . . Q2' 



19th Sept. ... ... . 56-4 



Largs, 13th ... . . 61-5 



19th ... . 58-5 



Brodick Bay, 15th ••• ... ... . . 61'3 



18th ... . 60- 



19th ... . 61- 



The circumstances attending the rapid change noted be- 

 tween the 30th June and 6th July, deserve to be noticed, for 

 the heat of the weather had no part in it. From the end of 

 June till the 5th of July the sky was mostly overcast, with 

 heavy showers at intervals, and the temperature so much be- 

 low what it had been in June, that there was no reason for 

 supposing that the deep waters of this part of the estuary 

 could be much changed in temperature by radiation. The 

 rise of 7^° was due to a thunder-storm which extended over 



