of the Fishery Board for Scotland. 



411 



months of the year, and again in the last four, and higher in summer. The 

 depth of water being considerable (24 fathoms), the curve of tempera- 

 tures of the lowest layers does not show the same fluctuations correspond- 

 ing to slight changes in the air temperature that the surface curve does, 

 aud in July, when the surface temperature reaches a first maximum, the 

 bottom water is not so markedly heated, but shows a steady rise. The 

 arrest of the falling of the temperature in November, shown in the case 

 of the Abertay station, is also evident in the North Carr curves. 



The mean annual densities of the water at 9 a.m. for 1892 were at the 

 surface 1025*4 (salts^ 3-24 per cent.), and at the bottom 1025*5 (salts, 

 3 -26 per cent.). At 3 P.m. they were 1025*5 at the surface and 1025*6 

 (salts, 3*27 per cent.) at the bottom. 



The highest and lowest monthly means are compared with those of 

 1891 in the following table : — 



Mean Monthly Specific Gravities, North Carr, Maximum 

 and Minimum. 





1892. 



1891.* 





9 a.m. 



3 P.M. 



9 A.M. 



3 P.M. 



Maximum — 

 Surface . . j 



Bottom . . | 



1026-1 



(Sept.) 

 1026*2 

 (July, Sept.) 



1026-3 

 (July, Sept.) 



1026-5 

 (July, Sept.) 



1025-4 

 (July) 

 1025*6 

 (July, Sept.) 



1025*5 

 (July, Sept.) 



10257 

 (July, Sept.) 



Minimum — 

 Surface . . 



Bottom . . j 



1024-3 

 (Feb.) 

 1024-4 

 (Feb.) 



1024-1 

 (Feb.) 

 1024-4 

 (Feb.) 



1024-6f 

 (April) 

 1024-7 

 (Nov.) 



1024 *6f 

 (April) 

 1024*9 

 (Dec.) 



The densest water was found at 3 p.m. on July 9 — surface 10287, 

 bottom 1028*4 ; and the least dense on the surface on February 9 and 1 1 

 at 3 p.m. was 1023*0, and at the bottom on February 18 at 9 a.m. aud 

 February 19 at 3 p.m. was 1024*0. 



Oxcar Lighthouse. 



The observations are made of the temperature of the air and of the 

 surface water, and of the specific gravity of the surface water very re- 

 gularly at 9 a.m. and 3 p.m. 



The mean annual temperature of the water for 1892 was 7°*6 in the 

 morning, and 7°*9 in the afternoon — a degree and a half lower than in 

 1891. 



The mean monthly temperature was highest in August, being 12°*5 at 

 9 a.m. and 12°*7 at 3 p.m., and lowest in March, when it was 3°*2 in the 

 morning, and 3°*5 in the afternoon. The mean monthly range was there- 

 fore 9°*3 and 9°*2, compared with 10°*4 and 10° *8 in 1891, both maximum 

 and minimum being lower in 1892. The temperature of the air was 

 markedly lower in 1892 compared with 1891, and at this station, which 

 stands where the estuary merges into the firth of the Forth, the effect of 

 the sun's heat is much more powerful than tidal influence. 



* Eight mouths' observations, 

 t Ten-day mean. 



