SEA.> 
Tlie ascent of the sea-water, for the for- 
mation of springs, by a subterranean circu- 
lation of its water to their sources, has 
been a great objection with many, against 
the system of their being formed of tlie sea j 
but Dr. Plot has observed, that tlierc are 
many ways by, which the water may as- 
cend above its .own level : 1. By the means 
of subterranean heats. 2. By filtration. 
3 . By the unequal height of several seas. 
4. By the distance of the centre of magni- 
tude from the centre of gravity, in the ter- 
raqueous globe : the superficies of the Pa- 
cific Sea is said to be further, from the cen- 
tre of gravity, than the top of the highest 
hill on the adverse part of the globe. And, 
5. By the help of storms. The sea-water 
actually ascends above its own level, com- 
ing into wells whose bottoms lie higher 
than the surface of the sea at high-water 
mark. 
Witli regard to the saltness of the sea- 
water, it is very rationally Judged to arise 
from great multitudes both of mines and 
mountains of salt, dispersed here and there 
in the depths of theti^ea. The salt being 
continually diluted and. dissolved by the 
water, the' sea becomes impregnated with 
its particles throughout ; and for this rea- 
son the saltness of the sea can never be di- 
minished. Dr. Halley supposes, that it is 
probable the greatest part of the sea-salt, 
and of all salt lakes, as the Caspian Sea, the 
Dead Sea, the Lake of' Mexico, and the 
Titicaca, in Peru, is derived from the wa- 
ter of the rivers which they receive ; and 
since this sort of lakes has no exit or dis- 
charge, but by the exhalation of vapours ; 
and also since these vapours are- entirely 
fresh, or devoid of such particles, it is cer- 
tain, that the saltness of the sea and such 
lakes must, from time to time, increase, and 
therefore, the saltness at this time is greater 
than at any time heretofore. He further 
adds, that if, by experiments made in dif- 
ferent ages, we could find the different 
quantity of salt, which the same quantity 
of water (taken up in the same place, and 
in all other the same circumstances) would 
afford, it would be easy from thence, by 
rules of proportion, to find the age of the 
world very nearly, or the time wherein it 
has been acquiring its present saltness. 
The Bishop of Landaff has recommended 
a most simple and easy mode of ascertain- 
ing the saltness of the sea in any latitude : 
we insert it in his own words. 
“ As it is not every person who can make 
himself expert in the use of the common 
means of estimating the quantity of salt cort. 
tained in sea- water, I will mention a method 
of doing it which is so easy and simple, that 
every common sailor may understand and 
practise it, and which, from the trials I 
have made of it, seems to be as exact a 
method as any that has yet been thought 
of. Take a clean towel, or any other piece 
of cloth, dry it well in the sun, or before 
the fire, then weigh it accurately, and note 
down its weight ; dip it in the sea water, 
and when taken out, wring it a little till it 
will not drip, when hung up to dry ; weigh 
it in this wet state, then dry it either in the 
sun, or at the fire, and, when it is perfectly 
dry, weigh it again. The excess of the 
weight of the wetted cloth above its origi- 
nal weight, is the weight of the sea-water 
imbibed by the cloth ; and the excess of 
the weight of the cloth after being dried, 
above its original weight, is the weight of 
the salt retained by the cloth ; and by com- 
paring this weight with the weight of the 
sea-water imbibed by the cloth, we obtain 
the proportion of salt contained in that spe- 
cies of sea-water. 
“ Whoever undertakes to ascertain the 
quantity of salt contained in sea water, ei- 
ther by this or any other method, would do 
well to observe the state of tlie weatlier 
preceding the time when the sea-water is 
taken out of the sea, for the quantity of 
salt contained in the water near the surface 
may be influenced both by the antecedent 
moisture and the antecedent heat of the at- 
mosphere.’’ 
Whether the sea is salter or not at dif- 
ferent depths, has not yet been properly 
ascertained ; but that its temperature varies 
considerably in proportion to the depth, w e 
have decisive proof.' 
“ With respect to the temperature,” says 
Bishop Watson, “ of the sea at different 
depths, it seems reasonable enough to sup- 
pose, that in summer time it will be hot- 
ter at the surface than at any considerable 
depth below it, and that in winter it will be 
colder. 
“ Mr. Wales describes the instrument he 
made use of for trying the temperature of 
the sea at different depths, in the following 
terms : ‘ The apparatus for trying the sea- 
water at different depths consisted of a 
square wooden tube of about eighteen 
inches long, and three inches square exter- 
nally. It was fitted with a valve at the 
bottom, and another at the top, and had a 
contrivance for suspending the thermome- 
ter exactly in the middle of it. When it 
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