pended matter, the second less
thick, and the third still less thick. Thus the green brightened as
the suspended matter diminished in amount.

Previous to the fourth observation our excellent navigating
lieutenant, Mr. Brown, steered along the coast, thus avoiding the
adverse current which sets in, through the Strait, from the Atlantic
to the Mediterranean. He was at length forced to cross the boundary
of the Atlantic current, which was defined with extraordinary
sharpness. On the one side of it the water was a vivid green, on the
other a deep blue. Standing at the bow of the ship, a bottle could be
filled with blue water, while at the same moment a bottle cast from
the stern could be filled with green water. Two bottles were secured,
one on each side of this remarkable boundary. In the distance the
Atlantic had the hue called ultra-marine; but looked fairly down upon,
it was of almost inky blackness--black qualified by a trace of
indigo.

What change does the home examination here reveal? In passing to
indigo, the water becomes suddenly augmented in purity, the suspended
matter becoming suddenly less. Off Tarifa, the deep indigo
disappears, and the sea is undecided in colour. Accompanying this
change, we have a rise in the quantity of suspended matter. Beyond
Tarifa, we change to cobalt-blue, the suspended matter falling at the
same time in quantity. This water is distinctly purer than the green.
We approach Cadiz, and at twelve miles from the city get into
yellow-green water; this the London examination shows to be thick with
suspended matter. The same is true of Cadiz harbour, and also of a
point fourteen miles from Cadiz in the homeward direction. Here there
is a sudden change from yellow-green to a bright emerald-green, and
accompanying the change a sudden fall in the quantity of suspended
matter. Between Cape St. Mary and Cape St: Vincent the water changes
to the deepest indigo, a further diminution of the suspended matter
being the concomitant phenomenon.

We now reach the remarkable group of rocks called the Burlings, and
find the water between the shore and the rocks a strong green; the
home examination shows it to be thick with fine matter. Fifteen or
twenty miles beyond the Burlings we come again into indigo water, from
which the suspended matter has in great part disappeared. Off Cape
Finisterre, about the place where the 'Captain' went down, the water
becomes green, and the home examinat