410 



Part HI- — Meventh Annual Report 



North Carr Light- Vessel. 



Owing to the constant pitching of the vessel, the instruments (especi- 

 ally the hydrometer) cannot be read so accurately as at a rock station. 

 AVhen the sea runs high great difficulty is experienced in makiug any 

 observations, and in very rough weather the attempt to continue the 

 record has to be given up. In a fog the observers have other duties 

 which prevent them making the observations. 



The records are sufficiently continuous to give good enough means, but 

 the data are not so trustworthy as those of steady stations. 



The mean annual temperature of surface water at North Carr was 7°*4 

 at 9 a.m. and 7°*5 at 3 p.m., fully a degree below that of 1891. At 12 

 fathoms the mean was 7 0, 8 and 8 o, 0, and at the bottom 7° -9 and 8 U, 0, in 

 the forenoon and afternoon respectively. The bottom mean temperature 

 was only seven-tenths of a degree below that of 1891. 



The minimum and maximum mouthly means for 1892 are both lower 

 than those for 1891, viz. : — 



Mean Monthly Temperatures, North Carr, Maximum and Minimum. 





1892. 



1891. 





9 A.M. 



3 p.m. 



9 a.m. 



3 BUM. 



Minimum — 



Surface . . 

 Bottom . . 



3°2 (Feb.) 

 4-2 (Mar.) 



3°4 (Feb.) 

 4-0 (Mar.) 



4°9 (Mar. ) 

 4 7 (Mar.) 



5-1 (Mar.) 

 4 7 (Mar.) 



Maximum — 

 Surface . . 

 Bottom . . 



11-5 (Aug.) 

 11 p (Sept.) 



11-9 (Aug.) 

 11-6 (Sept.) 



12-4 (July) 

 137 (July) 



13-0 (July) 

 13-5 (July) 



Range — 



Surface . . 

 Bottom . . 



8'3 

 7-3 



8-5 

 7-6 



7-5 

 9*0 



7'9 

 8-8 



The range of monthly mean temperatures is somewhat less than for 

 1891 ; but in 1892, as in 1890, the range of surface temperatures is 

 greater than that of bottom temperatures, 1891 being anomalous in this 

 respect. 



Of temperatures of surface water the highest reading was 13°T, re- 

 corded at 3 p.m. on September 8, and the lowest was 2° '2, recorded at 9 

 A.m. on February 19. The highest temperature of bottom water was 

 13°'3 at 3 p.m. on July 9, and the lowest was 3°*3 at 9 a.m. on March 10. 

 The extreme range is thus 10° -9 for the surface and 10° '0 for the bottom 

 water. 



The mean annual temperature of the air was the same in spring as tha'u 

 of the last days of April and the first period of May, and in autumn it 

 corresponded to that of the middle of October in the forenoon, and to that 

 of the first half of November in the afternoon. The surface water reaches 

 the annual mean in the middle of May and towards the end of 

 November, both in the forenoon and in the afternoon. The bottom layers 

 have the mean annual temperature at the end of May and the beginning 

 of June, and in the last w 7 eek of November and the first week of 

 December. 



The curves of surface and bottom temperatures (fig. 5) show the usual 

 characteristics — the surface temperature being lower during the first four 



