Page:Narrative of a Voyage around the World - 1843.djvu/30

 xxiv remote from any bank, to have a deep cast of the lead every ten or twenty miles, according to the distance from the shore. This might sometimes lead to useful discoveries; and in order to abridge the labour, as well as to prevent the unwholesome effect of wet sleeves, the sounding which should be always employed on these occasions. No consistent account of the currents along the western American coast has been yet framed, though in no part of the world would it be of more importance and value. Observations, therefore, to determine the direction and strength of the current, should not be left to be inferred from the mere error of the dead reckoning, when traversing the sea in the offing, nor to the casual set of the boats when employed in-shore, but should be systematically made, for the express purpose of forming a general view ol this interesting subject, and which can only be effected by a great accumulation of data.

In applying this rule to the extensive ocean which will be more than once traversed by the present expedition, it may be as well to divide the inquiry into distinct questions.

1. The actual set and direction of the current in all parts that the vessels may visit.

2. Are the currents permanent, or in what degree are they modified by the daily sea and land breeze, or by the periodic monsoon, or by the issue of the large rivers?

3. To what distance does the regular current extend from the coast? and where do the neutral space and counter-current begin?

4. Is the general direction of the permanent current parallel to the shore, or oblique?

5. To what depth do these currents extend downwards?

The comparative temperature of the atmosphere and