FUOM THE EDDYSTONE GROUNDS TO STAltT POINT. 375 



shown by the observatious made by ]Mr. H. N. Dickson (No. 21, pp. 

 166-169) in 1891. Dickson's stations I. and XV. are suflicieutly near 

 to be of value. 



Station I. Bolt Head N.E. by E. U miles. June loth, 1891. 



Density (^S,,.,,). Surface 1-02601 



19 fathoms 1-02599 



Station XV. Bolt Head N.N.E. 1^ miles. June 17th, 1891. 



Density (.Si^-sg). Surface 1-02598 



19 fathoms 1-02602 



In November, 1891, and March, 1892, samples were also taken by 

 Dickson at the above Station I., as well as at other stations in various 

 parts of the Channel, and he reports (No. 21, p. 273) that "the examina- 

 tion of these samples has shown that the water over the area under 

 consideration is normal Atlantic water throughout." 



No accurate data can be given as to the amount of solid matter 

 in suspension in the water at various times, as no attempts have been 

 made either to determine this directly or to measure the degree of 

 transparency of the water. It is possible, owing to the nearer proximity 

 of the coast in the neighbourhood of Prawle Point, that the water 

 there at the 30-fathom line may at times be somewhat more muddy 

 than that in the neighbourhood of the Eddystone. 



The Movements of the Water. 1. Wave Action. No satisfactory 

 method has yet been devised for measuring directly the amount of wave 

 action at various depths. There is, however, considerable evidence 

 to show that a certain amount makes itself felt on the grounds under 

 consideration, and that although the amount is small it is appreciably 

 different on the diff'erent grounds. 



That the amount of wave action extending to the bottom is generally 

 slight is shown by the abundance of the hydroids Antennularia 

 antennina and Aglaophenia viyi'iophi/llum, which fix themselves in the 

 sand or fine gravel by a felt-work of root-fibres in such a way that they 

 would certainly be torn up by any violent movement of the water, and 

 on the fine sand grounds Cellaria is abundant fixed in a similar way. 

 On the gravel also to the west and south-west of the Eddystone the 

 ascidiau Polycarpa varians (Heller) is very plentiful, and is generally 

 attached only to the gravel itself, for nearly all the specimens which 

 come up in the dredge are found to have their bases covered with 

 pieces of gravel to which they are firmly fixed. 



The distribution of Alcyonium digitatum (see p. 457), on the other 

 hand, seems to indicate that the amount of movement of the bottom 

 water is appreciably less on the grounds where the depth is greater than 

 33 fathoms than it is upon those from 28 to 33 fathoms. 



