424 



Pari Tft. — Eleventh Annual Liepon 



Loch Strivan moot the northern extension of the deep water of the Arran 

 Basin * coming from the south, and the Dunoon Basin * coming from the 

 east. A channel of deep water (over 30 fathoms) runs from Loch Strivan 

 across the mouth of the bay and joins the deep channels of the basins to 

 the east and south. The water in this channel has been proved to be 

 greatly affected by the direction of the wind acting on the long straight 

 valley of Loch Strivan, and tending to produce strong superficial or under 

 currents. 



The following is a summary of the dates at which forenoon and after- 

 noon observations were made by the cruisers at anchor, in from 8 to 15 

 fathoms in Rothesay Bay : — 



Number of Days when Observations were made in — 





Jan. 



Feb. 



Mar. 



Apr. 



May. 



Jun. 



"a 



< 



Ph 



<D 

 Ul 



Oct. 



Nov. 



Dec. 



1887, . . 



1888, . . 



1889, . . 



1890, . . 



1891, . . 



1892, . . 



13 

 6 



8 

 8 



12 



9 

 6 

 5 



7 



9 

 3 

 4 



5 



2 



1 



3 

 4 

 3 



4 

 6 



3 

 2 



3 

 6 



3 





3 

 5 

 3 

 2 



20 

 22 

 9 

 7 

 7 

 4 



20 

 10 

 9 

 3 

 3 

 7 



23 

 15 

 8 

 4 

 3 

 8 



Total, . 



35 



32 



28 



13 



15 



9 



3 





13 



69 



52 



61 



This shows a good number of observations for the winter months, but 

 practically none for the warmest period from June to September. 



The range of temperature between surface and bottom varied con- 

 siderably with the season, but was never great, probably because there are 

 no observations for the months of great range. The highest surface 

 temperature for any 10-day period was 13°"7 for June 1-10, 1892. 

 In other years the warmest period occurred in September or October, with 

 a temperature of about 12 o, 0. The coldest surface water for a 10-day 

 period was 4° -7 at the end of February 1887 ; the period of absolute 

 minimum for each year was always in the middle, or end of February, or 

 the beginning of March ; at these times the surface water was considerably 

 colder than that below. The warmest month appears to have been 

 September 1890 (surface 13°3, 10 fathoms 12°-7), the coldest March 1892 

 (9 a.m., surface 5°*1, 10 fathoms 6 o, 0). The range of diurnal temperature, 

 i.e., between the 9 a.m. and 3 p.m. observations is of some interest. So 

 far as the rather slender data, allow us to judge, the mean diurnal range for 

 the whole period was 0°3 at the surface, and 0°'l at 10 fathoms. The fact 

 of afternoon warming only comes out in the period from March to May, 

 and from November to January. Its absence, or very small value in 

 September and October is very marked, but doubtless the afternoon 

 warming was most marked at the period during which the cruisers were 

 absent from Rothesay Bay. The distinct evidence of afternoon warming in 

 November, December, and January is difficult to understand or explain. 

 Too much stress must not in any case be laid on these observations. 



A special Table is devoted to a comparison of Rothesay with other 

 Stations ; the symbol -I- means that the surface w r ater at Rothesay is 

 warmer, the symbol — that it is colder than the surface water of the other 

 Station at the same times. The figures following the signs give the 

 number of degrees or fractions by which the temperature at Rothesay 

 exceeds or falls short of that at the other Stations. 



* These names are applied to the physieal divisions of the Clyde Sea Area, as 

 deseribed in Dr Mill's paper already cited. 



