*99 
that often prevails to the Westward o/'Scilly. 
keepers will effect more, in the course of a summer, in the 
hands of a skilful practitioner, than all the science of Dr. 
Halley, during a long life ; for who could place a single 
cast of soundings, in the open sea, without the aid of a time 
keeper ? The current in question, must have disturbed every 
operation of this kind. It should be the task of the person, 
so employed, to note all the varieties of bottom, as well as 
the depths ; the time of high and low water ; setting of the 
tides, and currents, &c. Such a survey, skilfully conducted, 
might enable mariners to supply the want of observations of 
latitude, and of longitude ; and, of course, to defy the current, 
as far as relates to its power of misleading them. 
6th. It is certain, that the current in question may be 
somewhat disturbed by, or rather will appear to be blended 
with, the tides, at the entrances of the British and St. George's 
Channels ; but it is obvious that the current will have the 
same effect, in setting a ship out of her course, as if no tide 
existed ; because, whatever effect one tide may have, the 
next will nearly do away. But there are two particulars, 
well worth ascertaining ; and these are, first, the point at 
which the two tides of St. George's, and of the British Chan- 
nel separate, on the west of Scilly. And secondly, what de- 
gree of northing one of the streams has, more than the other. 
Because a ship, in approaching Scilly, from the west, on a 
flood tide, and keeping in a parallel which may be to the 
north of the point of separation of the two tides, (and conse- 
quently in the tide stream of St. George’s Channel) may be 
thrown too far to the north ; although, had she been far 
enough to the west, to receive the effect of the next ebb, this 
temporary, and alternate derangement of the course, would 
2 D 2 
