floats up to the 20th the wind continued from the southward and westward ;
it then hauled to the northward and westward, and finally into the northeast ;
and it was not until about this period, about 8 p. m. of the 20th, in latitude
25° 44' north, longitude 20° 23' west, that the ship could he considered
fairly to have entered the trades. This is a point unusually far south for
the northern boundary of these winds at this season, for it is not to be forgotten
that the northern and southern boundaries of the zone of the trade
winds are variable. The southeast has its northern boundary furthest to
the north during our summer ; the northeast is then weakest. In our winter
this state of things is exactly reversed. In our autumn the zone of the trades
reaches its greatest northern declination ; and in our spring it is at its utmost
southern limit.
On the 22d of December, the Commodore issued a general order promulgating
the directions of the Secretary of the Navy forbidding communications
to the public prints at home touching the movements of the squadron, and
prohibiting also such information through the medium of private letters to
friends. The Secretary also required that private notes and journals kept
by any members of the expedition should be considered as belonging to the
government until their publication should be expressly permitted by the Navy
Department.
A second general order, issued the next day, was as follows :
“ Entertaining the opinion that the talents and acquirements of the officers
of the squadron, if properly directed and brought into action, will be
found equal to a plain and practical examination and elucidation of the various
objects pertaining to the arts and sciences that may come under their
observation during the present cruise, and being aware of the limited accommodations
of the vessels under my command, I have invariably objected to
the employment of persons drawn from civil life to conduct those departments
more immediately connected with science.
“ Therefore I have to request and direct, that each officer of the respective
ships will employ such portions of his time as can be spared from his
regular duties and proper hours of relaxation, in contributing to the general
mass of information which it is desirable to collect ; and in order to simplify
and methodise these researches, a paper is subjoined particularising the various
departments in reference to which information is more especially wanted;
so that each officer may select one or more of those departments most congenial
to his tastes and inclinations.
“ All captains and commanders are required to render every faoility
consistent with the proper duties of their respective vessels to those officers
who may manifest a zealous co-operation in the pursuits herein specified ;
and it is to be plainly understood that I do not officially require the officers
to perform any involuntary duty. I shall exact that only which may come
within the legitimate sphere of my authority, leaving to the officers themselves
to engage, as far as they may see fit only, in those investigations which,
in an official point of view, may be considered as on their parts gratuitous.
“ I t will always give me the greatest pleasure to bring to notice the
labors of each and every individual who may contribute to the general
work.” *
During the 21st, 22d and 23d of December, the wind continued from the
northward and eastward; about noon of the 23d it inclined to the southward
of east, hauling around at night, however, more to the north; and on
the 24th, when the ship was abreast of Brava and Eogo, it stood at E.N.E.
The haze, however, was such that nothing more than a glimpse could be
obtained of Eogo; and the winds are thus particularly referred to above
because of their possible connexion, at this time, with the haze. They are
physical facts, and therefore ought to be recorded. This haze is common to
these latitudes, and is by many supposed to be caused by what is called the
“ Harmattan.” This is the name given to a wind which, passing over Africa,
takes up in its sweep, as is supposed, an impalpable dust, and carries it far
away to the westward. The Commodore himself had remarked the haze or
dust, on former cruises, more than five hundred miles west of the Cape de
Verd islands. When commanding a squadron, in 1844, on the western coast
of Africa, he had carefully noted several facts connected with this wind,
certainly the most remarkable on that coast. A thousand incredible stories
are told of its singular effects. I t is said, for instance, that its dry and
subtle properties will check or cure various diseases, heal up the most inveterate
ulcers, destroy cabinet work, break window glass, and stop the motion
of timepieces. But apart from these strange stories, it must still be said
that the effects of this wind are extraordinary. In some respects it resembles
the Sirocco, and also the Levanter of the Grecian archipelago.
I t commences about the middle of December, and continues until the
latter end of March. Like the Sirocco, it has been supposed to take its rise
in the deserts of Africa; but, unlike the Sirocco, instead of producing a
burning and oppressive temperature, it is a chilling wind. Its direction is
always from the land, and it sometimes increases to a strong breeze; it does
not, however, blow steadily during its season, but frequently intermits,
when land or sea breezes take its place.
At the Cape de Verds and the Gambia, the “ Harmattan ” appears to
* The subjects suggested by the Corunodore, in his order, embraced hydrography,
meteorology, naval architecture in its adaptation to war and commerce, military affairs,
geology, geography, terrestrial magnetism, philology and ethnology, artistic matters, costumes,
&c., religions, diseases and sanitary laws, agriculture, statistics of supplies, botany,
entomology, ornrthology, zoology, conchology, ichtiriology, and the magnetic telegraph;
and we trust the appendices to this narrative will show that the commander did not misjudge
either as to the attainments or zeal of his officers.