LIS 



Pari III. — Eleventh Annual Report 



Two minima of air and water temperatures were recorded in the spring 

 of 1892. In the middle ten days of January the air temperature was 

 1°*5 at 9 a.m. and 2°*4 at 3 p.m., the surface water at the same hours 

 being 3° 4 and 3 0, 6. In the last ten days of January the air temperature 

 had risen to 5°*6 and 6° "4, and the water to 3°*9 and 4 0, 2. During the 

 first ten days of February the air averaged 4° "2 and 6°*7, and the water 

 4° '5 and 4° "8. Then a slow fall took place until the normal minimum 

 was reached in the first ten days of March, when the mean temperature 

 of the air was 0°*9 and 3°*4, and that of the water 2°*7 and 3°*0. 



During the last ten days of April, and again at the middle of October, 

 the temperature of the air coincided with the mean of the year. The 

 surface water reached the mean annual temperature a little later — about 

 the middle of May and during the first fortnight of November. 



The temperature of the water rose steadily until the beginning of June, 

 when it fell during a cold spell in the middle of the month. It rose 

 again, and then fell during another cold period in July. The water was 

 warmest in August, and then grew colder, the temperature remaining 

 stationary during the warm period at the beginning of November and at 

 the end of the year. 



The extreme range of temperature of surface water was 10° *8, the 

 maximum being 13° "8 (Aug. 1, 4, and 25) and the minimum 3°*0 (Mar. 

 29). Compared with the range of 14°*4 of 1891, this is small. 



The mean specific gravity of the water was 1024*2, equivalent to 3*03 

 per cent, of salts. This is very little below the mean for 1891. 



The greatest mean monthly densities were 1025*0 at 9 a.m. in May 

 and August, and 3 p.m. in May ; and the least were 1023*0 at 9 a.m. in 

 November, and 1023*2 at 3 p.m. in November. 



But the maximum density registered in 1892 was 1025*8 at 3 p.m. in 

 May 12 and 14 and August 2, and the freshest water was found at 3 p.m. 

 on the last day of August and gave as low a specific gravity as 1014*1 — 

 much lower than any recorded in 1891, and, in fact, the lowest on record. 

 Exceedingly heavy rains had fallen during the two previous days, and 

 the large volume of fresh water brought down by the rivers must have 

 floated on the Salter water with comparatively little intermixing with it. 

 The lighthouse-keepers report that on the day when this very remarkable 

 reading was obtained no appearance of any tidal current could be seen on 

 the surface, but the upper waters flowed steadily seawards all day. The 

 relief boat which came to the lighthouse at this date had much difficulty 

 in making the rock owing to the strength of the outward flowing- 

 current. 



The specific gravity curve (fig. 6) shows the double minimum so marked 

 in the temperature curve in January and March, but to a much less degree. 



It would be interesting to compare the fluctuations in the catch of fish 

 at such stations as the Bell Rock, North Carr, and Oxcar, and see if the 

 numbers for the first station are most constant, and if the constant 

 variations of temperature and specific gravity of the water in the Forth 

 estuary influenced the success of the fishermen. The effect of the floods 

 at the end of August making the waters of the estuary fresher and 

 muddier than usual on the take of fish might also be ascertained. 



Dunbar Harbour. 



The observations from this station, begun in the summer of 1891, have 

 been obtained by Mr Jamieson. Unfortunately, Mr Jamieson's other 

 duties prevent the record from being continuous. 



The mean temperature of the water for 1892 was 8°*0, the forenoon 



