il
Others said that they did not recollect having seen it before.
All seemed surprised that I should attach such interest to it.
“ I f it be necessary to describe the appearance of the sea, I
should say that its surface was covered with a compact stratum
of but little thickness, but of a fine texture, of a brick red,
slightly tinged Avith rouge ; saAvdust of this colour, of mahogany,
for example, Avould produce very nearly the same
effect. I t seemed to me, and I said at the time, that It was
a marine plant. No one seemed of my opinion ; so with a
pail tied at the end of a rope I Avas able to gather, with one
of the sailors, a certain quantity of the substance : this Avith
a spoon I introduced into a Avhite glass bottle, thinking
that it Avould be the better preserved. The next day the
substance had become of a deep violet, and the water had
taken a pretty pink tinge. Fearing that the immersion
Avould hasten the decomposition instead of preventing it, I
emptied the contents of the bottle upon a piece of cotton (the
same Avhich I remitted to you). The Avater passed through it
and the substance adhered to the tissue. In drying it became
green, as you actually saw it. I ought to add, tha t on the 15 th
of Ju ly Ave Avere by the side of the toAvn of Cosseir ; that the
sea Avas red the Avhole day ; tha t the next, the 16th, it was the
same until near mid-day, the hour at which we found ourselves
before Tor, a little Arabian village, the palms of Avhich Ave perceived
in an oasis on the border of the sea, beloAV the chain of
mountains Avhich descends from Sanai, even to the sandy shore.
A little after mid-day, the 16 th, the red disappeared, and the
surface of the sea became blue as before. The 17th Ave cast
anchor at Suez. The red colour had consequently shoAved itself
from the 15th of Ju ly , toAvards 5 o’clock in the morning, up
to the 16th, nearly an hour after mid-day; that is to say,
during thirty-two hours. During this interval the steamboat,
making eight knots an hour, as said the sailors, had
traversed a space of 256 miles, or 85 leagues and a third.
“ In the different works relative to Egypt and the Red Sea
which I have had occasion to read, I do not recollect to have
found mention made of a similar fa c t: it appears to me,
nevertheless, but little probable that it has not been obscrved
by others. I reproached myself for not having questioned
the Arabian pilot Avhom we had on board, and who
for tAventy years traversed that sea. This idea unhappily
presented itself too late.
“ I f it should be in your opinion worth the pains, I would
demand nCAv observations of the surgeon or officers of the
Atalanta, for it would be easy for me to write to them by
Avay of Alexandria.
“ Believe me, my dear Geoffrey, &c.
“ E venor D upont.”
Numerous other navigators and naturalists have noticed the
colouration of different portions of the ocean, but these for
the most part have not determined the exact nature of the
cause, most of them attributing the phenomenon to minute
animals. Crustáceos, and Mollusccs. T avo English naturalists,
in describing it, have distinctly stated the cause to be an
Alga, the species of which, hoAvever, they did not determine.
The first of these, Mr. DarAvin, observed the phenomenon
in the Atlantic ocean near Brazil, and not far from the Isles
of Abrolhos. The other. Dr. Hinds, of H. M. ship Sulphur,
encountered the same Alga at the same spot in which it was
originally discovered by Mr. Darwin, and again observed it
in the month of April 1837, while at anchor at Liberty, near
San Salvador, upon the western coast of America, latitude
14° north. Mr. Hinds on both occasions remarked tha t the
plant emitted a strong and penetrating odour, and many
persons on board experiencing an irritation of the eyes, followed
by an abundant secretion of tears, attributed the affection
to the presence around the ship of the Alga. Mr. H inds
took the precaution to preserve specimens of his plant, some
of which were entrusted to Mr. Berkeley for publication,
Avho forwarded them to Dr. Montagne, who ascertained that,
though belonging to the genus Trichodesmium, the plant was .
specifically distinct therefrom, and named it T. Hindsii.
I have been led, in having introduced the above account of
the colouration of the waters of the sea, to depart from the
strict limits of this work. The phenomenon is, however, so
T 2