OCEAN» the fea affumes a grey hue, and feems turbid, as i f it had loft its
limpidity. But often you are deceived by the Situation of the Iky
and clouds. Dark, cloudy weather involves likewife the whole
ocean in a grey hue. A ferene and clear Iky tinges the waves with
the fineft -berylline or blueilh-green colour. I f a cloud appears, it
gives to a fpot o f the fea a hue quite different from the reft; and,
i f not well attended to, often alarms the navigator with the
fear o f foundings, or even Ihoals. A judicious eye, conducted by
long experience, can alone- diftinguilh properly in thefe cafes.
But, upon the whole, it cannot be too much recommended to navigators,
efpecially in unexplored feas, to make ufe of the lead in
every doubtful fituation * .
O f the S a l t n e s s o f the O c e a n .
I t has been fufpedted, that the faltnefs o f the ocean is not every
where equal. Some affert the fea to be falter under the Line than
towards the Poles-f-j that the great oceans are falter than the
fmaller feas, which are almoft included by land, viz. the Baltic,
the Mediterranean, the White Sea near Archangel, the Perfian and
the Arabic Gulphs, & c . ; that its faltnefs increafes with its
large
* See Me. Dairy male's Memoir o f a Chart o f the Southern Ocean. jp. j ,
j- BufFon’s Hiftoirc Naturelle, tom. 2. p. 79. edit, in i2mo.
depth ; and laftly, that -the high fea, at a great diftance from
land, is falter than near it, and efpecially near places where
large rivers fall into the -fea. I had no opportunity to make
the neceffary experiments to afeertain or to refute thefe affertions,
as 1 was obliged to fet out upon this expedition almoft at a moment’s
warning, and could not therefore provide any apparatus neceffary
for that purpofe. T h e above-remarks may, however, ferve
to future navigators, as a hint o f what is ftill wanted to be obferv-
ed, relative to the faltnefs o f the ocean. I ihould therefore pro-
pofe to them, to procure the apparatus deferibed by Mr. Wilke, in
the Memoirs of the Swedifb Academy, vol. 33, n. 6 o f the i f t quarter,
which ferves to bring the water of the ocean up from any
given depth ; -they ought al-fo to be provided with an accurate and
nice hydroftatical balance, in order -to afeertain the fpecifrc gravity
o f any water or liquid ; or they may make ufe, for convenience-
fake, o f a halafcofium, cohfifting o f a hollow globe o f ivory, into
which a tube o f about five or fix inches mull be inferted, on which
the different fpecific weights o f pure water, and its various mixtures
with certain quantities of -common fait, are marked in degrees;
fo that, by immerfing this fimple machine into fea-water,
it would be ealy to afeertain the degrees o f its faltnefs. This machine
would likewife ferve to afeertain the comparative purity and
weight o f every water found in rivers, wells, & c . & c .
I It
OCEAN.