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Part III. — Thirteenth Annual Report 



which is now considered necessary for perfectly satisfactory results, and 

 vessels of ampler dimensions are being sent to the stations where density 

 determinations are made. 



As regards the future, the completeness of the physical observations 

 should depend on their value, which can be ascertained by the comparative 

 study of physical and other results, as has been already pointed out. The 

 Oxcar and Ardrishaig stations have been given up, owing to the 

 removal of the observers, and it is highly desirable that satis- 

 factory observations should be obtained from the North Carr lightship, 

 which floats in comparatively deep water. The new lighthouse, forty 

 miles west of the Orkneys, might be utilised, and would be an important 

 station ; and an attempt should be made to make observations at places 

 detailed in the Eleventh Annual Report. The cruiser observations at 

 fixed stations should be increased as far as possible ; and the estimation 

 of the colour of the sea undertaken by means of Forel's Xanthometer, as 

 suggested by Mr Dickson in the Twelfth Annual Report (p. 347). 



In the correction of the observations, in the reduction of specific 

 gravities to constant temperatures, and in the preparation of the tables, I 

 have had the assistance of Mr W. S. Bruce, Mrs F. D. Herbertson, B.A., 

 and Mr James Wood, M.A., all of whom I desire to thank for their 

 services. 



TEMPERATURE OBSERVATIONS, 1893. 



The mean annual temperature of the water at the East Coast Stations 

 during 1893 was considerably higher than in 1892, being almost the same 

 as in 1891 and lower than 1890. The morning surface temperature at 

 the Bell Rock was 8°-5 in 1893, 7°'7 in 1892, 8°-6 in 1891, and 9°-0 in 

 1890; and a similar relationship exists between the means of the other 

 East Coast stations, except for Oxcar in 1890, which had a relatively 

 much lower annual temperature than the other stations that year, probably 

 due, as Dr Mill has suggested (Ninth Annual Report, p. 356), to the 

 summer readings being far too low. The very low temperatures that 

 characterised the beginning of 1 893 led to some confusion in the records, 

 one of the observers being ignorant of how to read the thermometer 

 properly when the temperature was below 0° C. This makes the tables 

 for the west coast incomplete, but the comparison of the actual records 

 for the west coast with those of past years shows that 1893 resembled 

 1891 in the mean, being much warmer than 1892. 



The extremes of monthly temperatures were very marked in 1893, and 

 differentiate it from 1891, when the minimum temperatures were much 

 higher. The range of monthly temperatures at the Bell Rock in 1893 is 

 about a degree above that for 1890 and 1891, and nearly a degree and a 

 half above that for 1892, due more to the warmer summer temperature 

 in the case of the Bell Rock, but the lowness of the minima at Abertay 

 allows the same remarks about the range of temperature to be applied to 

 this station, except for 1890, when the range then was exceptionally little. 

 The west coast stations show high maxima and low minima, with greater 

 range of temperature in 1893 than 1891 and still more so than 1892. 



Coming to examine the actual extreme readings the same remarks apply. 

 At the west coast stations many readings were below zero at Ardrishaig 

 in the early weeks of 1893, while those at Stranraer and West Loch 

 Tarbert were only 1°'0, whereas the maxima were at Ardrishaig 15°'9 

 (July 11 and August 16), Brodick 17°'4 (August 15), West Loch Tarbert 

 20° "4 (July 3), and Stranraer 17°'2 (June 8). The greatest temperature 

 differences were thus over 16°0 for Ardrishaig (the exact minimum cannot 



