being 56°; and at sixty miles off the land, at two hundred fathoms, it was 43°.5, the surface being 61°.
All these circumstances combine to show that a northerly current of very limited extent, but of considerable force, exists from the Cape of Good Hope, along the western coast of Africa; which, in general terms, may be represented by a volume of water sixty miles wide and two hundred fathoms deep, averaging a velocity of about a mile an hour, and of the mean temperature of the ocean, running between the shores of Africa and the waters of the adjacent sea. The cloud of mist which hangs over this stream of cold water is occasioned, of course, by the condensation of the vapour of the superincumbent atmosphere, whose temperature is generally so many degrees higher than that of the sea. It is sufficiently well defined to afford useful notice to seamen of their near approach to the land.
We anchored on the evening of the 17th in Simon's March 17.Bay, and immediately commenced the necessary comparisons of our magnetic and other instruments, the sandstone formation of the country being more favourable for the purpose than that of any other place we had touched at since leaving England. Observations for the effect of the ship's iron on the various instruments employed were made in both ships, as also, by the kind and ready assistance of Captain Puget, on board of the "Melville," the first two-decker on which I had ever had an
