Waters in the Estuary of the Mersey at Liverpool. 309 



change is not due to the altered temperature of the air or to 



warm rains, but chiefly to the influence of westerly winds, 



which mix the warmer waters of the ocean with the water 



cooled down during calm weather. 



In April 1845, the temperature of the Mersey water ranged ^ „ 



from ... ... ... ... 43 to 49*6 



May, 

 June, 

 July, ... 

 August, ... 

 September, 

 October, 

 November, 

 December, 

 January 1846, 



49-8 to 53'3 

 54 to 61 

 59 to ^2-2 

 60-3 to 58-5 

 61 to 55 

 53-5 to 61 

 48-3 to 46 

 43 to 42-5 

 42 to 45 



On the 19th July the temperature of the Mersey waters 

 was 62° within seven hours. With the same apparatus I took 

 the temperature of the sea- water in Ramsay Bay, Isle of 

 Man, when the thermometer indicated 56°, or 6 degrees lower, 

 about 7 P.M., after the influence of the full day's sun. This 

 diff*erence, I believe to be due to the power of the solar rays 

 on the turbid waters of the Mersey and the heat absorbed 

 by the banks, which act, under the powerful summer's sun, 

 like so many sand-baths, which indeed is found by every 

 bather who enters water that has flowed over sands exposed 

 to the sun. On the 20th July, in the estuary of the Clyde, 

 opposite Loch Long, where the shore is steep, the tempera- 

 ture was 54°, and in Tobermory Bay, two days later, with 

 bright fine weather, 56°. In the frosts of winter these dif- 

 ferences would be reversed ; and when the waters of the 

 Mersey are at 35°, Ramsay Bay, or the estuary of the Clyde, 

 would nearly correspond with the temperature of the ocean, 

 40° to 42°. The change in latitude from the Mersey to the 

 Isle of Man can only very slightly aff^ect the midsummer 

 temperature. 



On tJiP, Air dissolved in Sea-water at Summer and Winter 

 Temperature. 

 At the time the observations given above were made, I 

 availed myself of the opportunity to try with care the volume 

 of air iu sea-water at diff^erent seasons. In summer, sea- 

 water, of temperature 62°, gave out at the rate of 2 cubic 

 inches of air to every 100 cubic inches. In winter, with 



