422 



Part TI I.— El< rt nth ^l/ini/a/ Report 



7.— OBSERVATIONS OF TEMPERATURE MADE ON BOARD 

 THE CRUISERS 'JACKAL' AND ' VIGILANT,' 1887-92. 



When it was decided in 1886 to make regular physical observations on 

 board the cruisers employed under the Fishery Board, a complete system 

 For taking the temperature of the water at various depths twice daily was 

 drawn up by Dr Gibson and Dr Mill. This is published in the Annual 

 Report (1887), p. 309. It was hoped that, by fixing the hours of 9 a.m. 

 and 3 p.m. for these observations, the cruisers moving from place to place 

 round the coast of Scotland would have opportunities for two temperature 

 soundings daily in fairly deep water. Many circumstances, however, have 

 alfected the value of the results, and they are far from being so satisfactory 

 for the purpose of following the annual changes of temperature as we 

 originally hoped. The naval routine on board the 'Jackal' frequently 

 prevented the vessel being stopped for observations when on a passage, 

 and most of the deep-water observations were made from the 'Vigilant,' 

 to whose Commander very much credit is due. The importance of the 

 deep-sea observations (i.e., in depths over 40 fathoms), is greatly limited 

 by their small number, and, after a vast amount of labour had been ex- 

 pended by us on the consideration and grouping of these data, we found 

 ourselves again reluctantly compelled to postpone their full discussion 

 until more have been collected. These deep-water observations will not 

 lose their value, but rather increase in importance by the delay in treating 

 them fully. They will serve in the open waters of the West Coast to con- 

 tinue the elaborate special researches made on the 'Jackal' in 1887, and 

 reported on in the Sixth Annual Report, p. 349. On the East Coast they 

 will connect the various special cruises of the 'Garland' and 'Jackal' in 

 the Moray Firth, and across the North Sea. In the partially enclosed 

 waters of the Clyde Sea Area, the results of the many admirably executed 

 deep-soundings of the 'Vigilant' will enable the temperature changes of 

 that great body of water to be traced from year to year. In themselves, 

 these observations would be insufficient for the purpose, but the earlier 

 years of observation coincided with the researches of the Scottish Marine 

 Station, which have been exhaustively discussed {see ' The Clyde Sea Area,' 

 by Dr H. R. Mill, Part I., Physical Geography ; Part II., Salinity ; Trans. 

 Roy. Soc. JEdin., xxxvi. p. 641 ; Part III., Temperature, Trans. Roy. Soc. 

 Edin., for 1893). The data for this region, obtained during the years 

 1887 and 1888, are given in a special Table in this Report, and their 

 significance is referred to in a special paragraph. The later observations 

 will enable a fairly trustworthy history of the temperature changes of the 

 Area to be compiled, but it is inadvisable to attempt this at present. 



As a matter of fact, most of the cruiser observations were made while 

 the vessels were at anchor, and many of them are valueless on account of 

 the shallow or stagnant water in which the vessel lay. In many natural 

 harbours, frequented by the cruisers, the water was fairly deep, and the 

 tidal currents strong enough to overcome the local irregularities, and give 

 a trustworthy character to the results. It is these observations in natural 

 harbours which have been selected for publication and discussion here. 



Twelve harbours formed the head-quarters of the cruisers for a sufficient 

 time to make this mode of treatment practicable. Of these, nine were on 

 the West Coast. Three of them were in the Outer Hebrides, viz., Storno- 

 way Harbour in the north, Castle Bay, Barra, and Vatersay Bay in the 

 south and south west of the great chain of islands. One was on the com- 

 paratively open part of the coast of the mainland off Oban, and the re- 

 maining five in the more sheltered harbours of the Clyde Sea Area, viz., 

 Campbeltown Loch and Lamlash in the south, Rothesay Bay and Fairlie 



