CLYDE SEA AEEA. 129 



Section V., 12th November 1886. — Three stations. Outside the sill a uniform rise 

 of temperature occurred from surface to bottom, which was at 52° '2. Inside, the water 

 o-rew warmer from 49° on the surface to 51° at sill-level, thence there was a steady fall 

 (most rapid as in IV. in a Sprung schicht about 17 fathoms) to 45°"8, i.e., 8°'4 lower than 

 outside. The isotherm of 46° had moved from 19 fathoms in IV. to 36 fathoms. On the 

 whole the isotherms showed a very slight seaward dip, a little masked by cooling at the 

 head of the loch. The tide was in the first quarter of flood when the observations in 

 rhc loch were made, and a little past high-water when the sounding was made outside. 

 There was no wind. 



Section VI, 22nd December 1886. — Three stations. Outside the bar a slight rise 

 of temperature occurred with depth, from 45°'6 to 48°, with a slight minimum a little 

 before the bottom. Inside, there was the same rise to 20 fathoms, at 25 fathoms a slight 

 maximum of 48°'0, and then a fall to 47°'6 on the bottom. There was a slight seaward 

 dip of the upper isotherms, but they were, as a whole, practically horizontal. The tide 

 was in the first quarter of ebb, and the wind was fresh from the north, with rain. There 

 was thus a surface current flowing out of the loch. 



Section VII., 8th February 1887. — Three observations were made, viz., at Dog Rock, 

 the Mouth, and off Carrick Castle, floating ice stopping farther work. The isotherms 

 were horizontal, except for the increasing cold of the surface landward. Outside, 45° was 

 found at 34 fathoms, and 45°'3 at the bottom ; inside, 45° occurred at 10 fathoms, and 

 47°"2 at the bottom, the maximum having thus worked its way fully down, and the bar 

 now serving to hold back warm water in the loch. The fall of temperature was very 

 rapid at the surface, falling from 39° to 44° in 2|- fathoms. The tide was at the first half 

 of ebb, and the wind was imperceptible. 



Section VIII, 25th March 1887. — Five stations were visited, the observations being 

 very complete. The surface isotherms showed a general seaward dip. It was flood-tide, 

 and the wind was fresh from the north, blowing against it. Outside, the temperature rose 

 from 42° "8 on the surface to 43° - 6 on the bottom ; inside, below the sill it was practically 

 constant at 44°, although an ill-defined area of slightly higher temperature appeared. 

 Compared with No. VII., it would seem that the superficial layers remained at nearly 

 constant temperature, while the mass below the sill had cooled down on the bottom from 

 47°'2 or more to 43" "9. This may be due to the mixing power of up-loch winds ; but at 

 the time of observation the down-loch wind appeared to be banking the cold surface 

 water against the inner side of the sill of the basin and causing a partial updraught at 

 the head. 



Section IX., 7th May 1887. — Four stations were visited. The temperature inside 

 below 10 fathoms was practically unchanged since No. VIII. The upper layers showed 

 rapid heating. The isotherms were practically horizontal, and the bar might have been 

 removed without sensibly disturbing the temperature distribution, that inside and outside 

 being alike. It was early flood-tide, and the wind was very light from south and west. 



Section X., lUh June 1887. — Observations were made at four stations. There was 



VOL. XXXVIII. PART I. (NO. 1). R 



