406 



Part III — Eleventh Anniud Report 



bottom 9°'8j the highest of any station, although that of Brodick ap- 

 proaches it. The wannest month was July — surface 1 6° 1, bottom 16° "2 ; 

 the coldest January, when both surface and bottom were at 4 o, 0 — a rang ) of 

 I2°'l for the upper and of 12°*2 for the lower layers of water. This is a 

 mean range over four and a half degrees more than at the Bell Rock and 

 over five degrees more than at Brodick. It is greater than that at any 

 other station. 



The maximum surface temperature was 17°*6 on 18fch July, the mini- 

 mum 2°'4 at 3 p.m. on January 21. The maximum bottom temperature 

 was 17°"5 on 18th July, and the minimum 2 0, 8 on January 21 at 3 p.m. 

 This gives an extreme range of 15°'2 for surface and of 14°*7 for bottom 

 water. The daily observations are printed in full in Table IX. (1891), 

 and curves drawn. The great range is accounted for by the shallowness 

 of the water, the greater part of the upper end of the loch not exceeding 

 2-1 J fathoms, which is the depth at the place of observation. 



Stranraer, Loch Ryan. 



The observations here were also initiated at the beginning of 1891. 

 They are made at 9 a.m. only, and are taken at the upper end of the loch, 

 in mid-channel, opposite the west end of the town of Stranraer, except in 

 rough weather, when they are taken from the end of the west pier. 



The mean annual temperature of the surface water was 9°*3, that of the 

 bottom water 9°*4, about the same as that of the other West Coast Stations, 

 and nearly a degree higher than at the East Coast Stations except Oxcar. 



The mean monthly surface temperature was a maximum during July, 

 when it was 15°'6 at the surface and 15°'5 at the bottom; and was a 

 minimum in January 4 o, 0 at the surface and 4°T at the bottom — a mean 

 range of 1 1 °'6 at the surface and 11 0, 4 at the bottom. 



The greatest surface temperature was 17°'0 on 25th June, and the 

 minimum 1 0, 6 on March 11— an extreme range of 15°'4; while the 

 maximum bottom temperature was 17°'0 on June 25, and the minimum 

 1°*8 on March 11 — a range of 15° '2. 



The curve, like those of other stations, shows a marked depression in 

 March, and a very rapid falling off of temperature after the mean 

 maximum in July. 



The observations for West Loch Tarbet and for Stranraer have been 

 published in extenso (Table IX., 1891), and curves have been drawn of 

 these daily observations. This will allow a comparison with oyster and 

 other fishing statistics, and show clearly the relation of temperature to the 

 various biological phenomena noted in another part of the Report. 



The many marked irregularities in the curve drawn from these daily 

 observations have been examined and compared with the tidal curve at 

 tue same hours. In many cases there appears to be a relation between 

 the variations of temperature and of tide, but so many contradictory cases 

 exist that no definite connection between the two can be shown. 



As yet no salinity observations have been made at the West Coast 

 Stations, but the proportion of salts at various parts of the Clyde Sea 

 Area has been worked out by Dr Mill.* Continuous records of salinity 

 extended over a long period, when compared with tidal and other influences 

 and discussed with respect to the distribution and catch of fish, would prove 

 valuable, especially as regards sudden changes of density • but much may 

 be discovered about the average percentage of salts from a discussion of 

 the temperature observations. 



* See paper on the ■ Clyde Sea Area,' by Hugh Robert Mill, I). Sc.. F.R.S. K., in 



the 'Transactions of the Royal Society of Edinburgh, xxxvi. p. 641 et seq. 



