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XXIIL— The Clyde Sea Area. By Hugh Eobert Mill, D.Sc, F.R.S.E. 

 (With Twelve Plates and Maps.) 



(Bead May 18, 1891.) 



Part I. — Physical Geography. 



The fjord-like inlets or sea-lochs which form so conspicuous a feature in the scenery 

 of the west of Scotland stand in marked contrast to the shallow, low-shored firths of 

 the east coast. When Dr John Murray decided to extend the physical and biological 

 work of the Scottish Marine Station to the west coast he foresaw that many interesting 

 conclusions were likely to be derived from the study of these isolated sea-basins. Various 

 papers, published by him and other workers, contain preliminary discussions of many of 

 the phenomena observed, fully justifying the anticipations which had been formed. 



For one year my work, as described in this paper, was carried out under the pro- 

 visions of an Elective Fellowship in Experimental Physics of the University of Edin- 

 burgh, to which I had been elected in 1886 ; and subsequently by a personal grant from 

 the Government Grant Committee for Scientific Research. The Committee also devoted 

 several sums of money in payment of expenses in compiling this discussion. The 

 Scottish Marine Station throughout gave the use of the steam-yacht " Medusa," and the 

 necessary apparatus. 



The work of the physical department of the Marine Station, of which I had charge, 

 was mainly to observe the temperature, salinity, and chemical composition of the water. 

 This was carried out systematically on the west coast during the years 1886, 1887, and 

 1888, and occasional observations were also made in 1889. For many reasons the con- 

 nected system of channels and sea-lochs lying within the Mull of Can tyre was more 

 thoroughly examined than the northern lochs, and it seems to me best to attempt a 

 somewhat complete discussion of these results, bringing in those obtained in Loch Etive 

 and the northern inlets, mainly for the purpose of explanation and comparison. I have 

 ventured to introduce the term Clyde Sea Area to designate this region, which is often 

 referred to loosely as " the Firth and Lochs of Clyde." It lies between latitudes 55° 

 5' and 56° 17' N., and longitudes 4° 30' and 5° 40' W. An outline of the configura- 

 tion and general physical geography of the region, derived mainly from the Admiralty 

 charts for the water, the one-inch maps of the Ordnance Survey for the land, and the 

 records of the Scottish Meteorological Society, is given as an essential introduction. 



The long peninsula of Cantyre forming the western boundary of the Clyde Sea Area 

 (see Plate I.) stretches southward to within 11 miles of the coast of Ireland, from 

 which it is separated by the North Channel. This channel, 1 1 miles wide, places the 

 Atlantic in communication with the Sea Area, and a wider channel, 21 miles across 

 at the narrowest part between the south-eastern end, the Rinns of Galloway, and 



VOL. XXXVI. PART III. (NO. 23). 5 E 



