138 DR HUGH ROBERT MILL ON THE 



The isotherms were practically horizontal, and the wind was light from the south and 

 south-west. 



V. 13^ November 1886. — Autumnal conditions had by this time fully set in, and the 

 barrier had no effect of separating water at different temperature. Below 5 fathoms the 

 water was homothermic about 51°'5, above that it grew cooler to the surface, the 

 isotherms showing no perceptible dip. The wind was northerly and very light. 



VI. 23rd December 1886. — Rapid cooling had taken place throughout the whole 

 mass of water, and the few isotherms which appeared on the section showed a slight 

 seaward dip in the deeper layers, but were practically horizontal near the surface, thus 

 showing no sign of any disturbance of equilibrium. The wind was variable, but very 

 light. 



VII. 7 th February 1887. — Although the range of temperature in this section was 

 small, the run of the isotherms was somewhat peculiar, probably representing the result 

 of some considerable previous disturbance. A wedge of warm water (over 45°) ran at 

 the depth of 1 5 fathoms from the head of the loch to beyond Clapochlar, with cooler water 

 above and below. The upper 10 fathoms at Clapochlar were homothermic at 42°, but at 

 the head and in the Dunoon Basin, on the other side, the surface-temperature was below 

 40°. The wind was blowing pretty strongly from south-east and south, or straight up 

 the loch, but the dip of the isotherms was too slight and indefinite to show the direction 

 of circulation. 



VIII. 20th March 1887. — In this section the conditions were almost homothermic: 

 the one isotherm, of 44°, which appeared showed a marked seaward dip at the head of the 

 loch, but the total range between surface and bottom being only 0° # 4, no argument can 

 be based upon it. The wind was very light from the west and south-west. 



IX. 6th May 1887. — Surface warming had fairly set in, and the isotherms showed 

 a slight seaward dip as far as Bogany. The wind was light from the north-west and 

 north, thus affording a sufficient explanation for the temperature diminishing from the 

 mouth to the head of the loch. 



X. lith June 1887. — A typical section of summer heating is here presented. The 

 isotherms, although varying in their inclination, showed on the whole a slight seaward 

 dip. There was no wind at the time of observation. The patch of water below 46° over 

 the plateau at the mouth of the loch appears as a striking feature in the section, but is 

 in realit} 7 inconsiderable, as the temperature falls only a fraction of a degree lower. 



XL ISth-lUh August 1887. — This section resembles those for the previous August 

 and September by illustrating the function of the plateau in barring off the cooler water 

 inside from the warmer mass entering from the Arran and Dunoon Basins. There was a 

 strong seaward dip of the isotherms from the head to Clapochlar, a horizontal run 

 thence to Bogany, beyond which the lines spread out. This was well defined by the 

 Sprung schicht between the temperatures 51° and 54°, and by the cooling of the surface 

 water (contrary to the usual order in summer) from 56°'2 at Clapochlar to 54° - 8 at the 

 Head. A fresh breeze blowing from the north-east accounted for this state of matters. 



