CLYDE SEA AREA. 149 



for 225 days in 1887-88, averaging 217 for the two years, nearly the same as for the 

 other divisions. 



By interpolating the values for the first three months of 1886, the mean annual 

 temperatures of air and water may be compared as taken from the curve. The figures 

 are given in Table LXII. 



Next to Loch Strivan (0°'9), no other division of the Area showed so low an excess 

 of surface water-temperature over the air as 1° # 2. Gareloch and Loch Goil showed 

 1 0, 8, Arran Basin and Channel 1°*7, and Loch Fyne 1°*5. The difference is, however, 

 very trifling, and may well lie within the limits of probable error. The surface water 

 was practically of the same temperature as that of Loch Strivan, but the mass of water 

 was o, 3 warmer in the Dunoon Basin, or 0°'7 warmer than the mass of water in Loch 

 Goil. 



General Summary. 



The scattered facts as to the thermal conditions of the Area are brought together 

 in Tables LXIII. to LXVIL, in order to make the similarities and contrasts between 

 the various divisions more marked. The only omissions are in the cases of the 

 Great Plateau, the Estuary, Loch Long, Loch Ridun and the Kyles of Bute, and the 

 Holy Loch. For the treatment of these there were either insufficient data, or no prospect 

 of finding results materially different from those for the similar divisions which have 

 been critically considered. All the figures in the tables are not equally trustworthy : the 

 method by which they were obtained is fully explained, and their relative value indicated 

 under the heads of the respective divisions. Table LXIII. gives an approximation to the 

 monthly mean temperature of the superficial 5 fathoms of water, calculated from the 

 seasonal curves of each of the seven divisions which are considered. The Gareloch was, 

 speaking generally, the warmest from May to September, and the coldest from October 

 to April. Its slight depth and land-locked character, and its exposure to the extreme 

 changes of temperature in the Estuary, combine to make it the most responsive to 

 changes in seasonal heating or cooling power. The Channel, in which oceanic influences 

 predominate over solar, was usually the warmest division from October to March, when 

 winter cooling was most active everywhere. During the summer months of 1887, the 

 Channel was colder than any other division, but at the same season in 1886, and probably 

 in 1888 also, the lowest surface temperatures were found either in Loch Fyne or 

 Loch Goil. 



The month of minimum surface temperature was usually the same in all the 

 divisions, and was April in 1886, March in 1887, and in 1888 both March and April. 

 At this season the surface temperature was nearly the same over the whole Area, the 

 greatest difference between the divisions being under 1°"5. The month of maximum in 

 1886 was September for the Channel and Gareloch, and October for the other divisions. 

 In 1887 it was August for the Gareloch, and September for the rest, and in 1888 it was 

 September for all the places where observations were made. The period of greatest 



