49 
dents into the two channels, and passes a good way to the west of 
Scilly. The decision as to which channel we are in should there- 
fore be made before we are in that depth; as, if we have got too 
far to the northward, and are making to the English channel, we 
will find the current described by Major Rennel,. and the prevalent 
southerly winds, greatly to obstruct our progress. 
Sixty miles west of Scilly, is Jones’s bank forty fathoms and ooze. 
This is the highest portion of a great ooze bed, which particularly 
distinguishes the St. George’s channel. It extends from the meri- 
dian of Scilly westward to near the edge of the bank of Soundings. 
This soft ground does not stick to the bottom of the lead when 
armed with tallow ; butter is therefore used for that purpose, As we 
have traced the other soundings to similar rocks on the shores, so 
this great ooze bed, if an original formation, may perhaps be con- 
sidered as a continuation of that great field of coal, which, begin- 
ning at Newcastle, passes through England to Bristol and South 
Wales. I think I have I found the same deposition in other similar 
situations. 
Nearer the Irish shore, we have again the graywacké, or brown 
slate sand, occupying all the bottom to the coast of Munster, as 
might be expected. That coast, from Waterford to the Blaskets, 
is one uninterrupted tract of brown slate. The Nymph bank is 
chiefly conglomerate, and from thence towards the Bristol channel I 
have no positive information of the nature of the soundings. 
It appears to be therefore possible, on rational principles, to de- 
lineate masses of the different soils of the bottom of the sea, as has 
been done for those of the land ; and, by instructing the pilot more 
carefully to ascertain the distinctions between the various kinds of 
sand or other matter which he may bring up from the bottom, so as 
more readily to refer to the corresponding part of his chart, it 1s 
