148 



DE HUGH EOBEET MILL ON THE 



The dates of the minimum and maximum temperature of the whole mass of water, 

 and the temperatures at those epochs, as deduced from the curves, were as follows : — April 

 15th, 1886, 42 o, 0; September 22nd, 1886, 52 0, 6 ; March 15th, 1887, 43°*4 ; September 

 1st, 1887, 55 o, 0; and April 15th, 1888 y 42°*0. The duration of. warming in days, and 

 the average rate of gain of temperature in degrees per day in the mass of the water, were 

 as in Table LXI. 



Table LXI. — Period of Heating and Cooling and Daily Rate of Change of Temperature in 



Dunoon Basin. 



Heating, 

 1886. 



Eate 

 per day. 



Cooling, 

 1886-87. 



Eate 

 per day. 



Heating, 

 1887. ' 



Eate 

 per day. 



Cooling, 



1887-88. 



Eate 

 per day. 



160 



+ 0°-066 



174 



-0°-053 



170 



+ 0°-070 



227 



-0°-57 



This approaches the distribution in the Arran Basin and Loch Strivan. The 

 average number of days of heating was 165, and of cooling 200; the ratio of the 

 time of heating to time of cooling being 100 : 121. The Channel and the Gareloch 

 are the only other divisions in which the time of cooling approached the same high 

 figure ; in the Arran Basin the periods of heating and cooling were the same, and in 

 the loch basins heating was the process requiring more time. As shown in Table LX. 

 the average rate of heating was 0°'074 per day, and the average rate of cooling 0°'058 ; 

 in other words, it required on the average 1 3|- days to raise the temperature of the mass 

 of water 1°, and 17 days to lower it by the same amount. The rate of change of 

 temperature decreased very slightly with increasing; depth. 



The air was warmer than the surface layer of 5 fathoms for 165 days in 1886, and 

 for 120 in 1887, or an average of 143, while it was colder for 210 days in 1886-87, and 



Table LXII. — Mean Annual Temperature of Air and Water for the Dunoon Basin. 



Year. 



I. Air. Mean 

 for Area. 



II. Air. Mean 



for Eothesay 



and Greenock. 



III. Water. 

 0-5 fms. 



IV. Water. 

 Mass. 



Difference. 

 Air II. and 

 Water III. 



Difference. 

 Air II. and 

 Water IV. 



1886 .... 



1887 .... 



46-2 

 470 



46-0 



47-2 



46-9 



48-8 



46-6 

 48-5 



-0.9 

 -i-6 



-o-6 

 -i"3 



Mean . . . 



46-60 



46-60 



47-37 



47-07 



-i'»5 



-°'95 



