SPRING. 
S. As to those who advance the capillary hy- 
pothesis, or suppose the water to rise from 
the depths of the sea through the porous 
parts of the earth, as it rises in Capillary 
tubes, or througli sand or ashes, they seem 
not to consider one principal property of 
this kind of tube, or this sort of attraction : 
for though the water rise to the top of the 
tube or sand, yet will it rise no higher, be- 
cause it is by the attraction of the parts 
above that the fluid rises, and where that 
is wanting it can rise no further. Therefore, 
though the waters of the sea may be drawn 
into flje substance of the earth by attrac- 
tion, yet it can never be raised by this 
means into a cistern, or cavity, to become 
the source of springs. 3. The third hypo- 
thesis is that of tiie sagacious naturalist. 
Dr. Halley, who supposes the true sources 
of springs to be melted snow, rain-water, 
dew, and vapours condensed. 
Now in order to prove that the vapours 
raised by the heat of the sun from the sur- 
face of the seas, lakes, and rivers are abun- 
dantly sufficient to supply the s))rings and 
rivers w'itli ftaish water, the Doctor made 
the following experiment : he took a vessel 
of water, made of the same degree of salt- 
ness with that of the sea, by means of the 
hydrometer ; and having placed a thermo- 
meter in it, he brought it, by means of a 
pan of coals, to the same degree of heat 
with that of the air in the hottest summer. 
He then placed this vessel, with the ther- 
mometer in it, in one scale, and nicely 
counterpoised it with weights in the other : 
after tWo hours, he found that about the 
sixtieth part of an inch was gone off in va- 
pour, and consequently in twelve hours, 
the length of a natural day, one tenth of 
an inch w'ould have been evaporated. From 
this experiment it follows, that every ten 
square inches of tlie surface of the water 
yield a cubic inch of water in vapour per 
day, every square mile 6,914 tons, and 
every square degree (or 69 English miles) 
33 )nillions of tons. Now, if we suppose 
tlie Mediterranean to be 40 degrees long, 
and 4 broad at a medium, w'hich is the least 
that can be supposed, its surface will he 
160 square degrees, from whence there will 
evaporate 5280 millions of tons per day, in 
the summer time. 1 he Mediterranean re- 
ceives water from the nine great rivers fol- 
lowing, m. the Iberus, the Rhine, the Ty- 
ber, the Po, tlie Danube, the Neister, the 
Borysthenes, the Tanais, and the Nile ; all 
the rest being smali, and their water incon- 
siderable. Now let us suppose that each 
of these rivers conveys ten times as much 
water to the sea as the Thames ; which, as 
is observed, yields daily, 76,032,000 cubic 
feet, which is equal to 203 millions of tons ; 
and therefore all the nine rivers will pro- 
duce 1827 millions of tons; which is little 
more than one third of the quantity evapo- 
rated each day from the sea. The prodi- 
gious quantity of water remaining, the doc- 
tor allows to rains, which fall again into the 
seas, and for the uses of vegetation, &c. 
As to the manner in which these waters are 
collected, so as to form reservoirs for the 
different kinds of springs, it seems to he 
this: the tops of mountains, in general, 
abound with cavities, and subterraneous 
caverns formed by nature to serve as reser- 
voirs; and their pointed summits, which 
seem to pierce the clouds, stop those va- 
pours which fluctuate in the atmosphere,^ 
and being constipated thereby, they preci- 
pitate in water, and by their gravity easily 
penetrate through beds of sand and lighter 
earth, till they are stopped in their descent 
by more dense strata, as beds of clay, 
stone, &c. where they form a bason or ca- 
vern, and work a passage horizontally, and 
issue out at tlie side of the mountain. 
Many of these springs running down by the 
vallies, between the ridges of hills, and 
uniting their streams, form rivulets or 
brooks ; and many of these, again, uniting 
on the plain, become a river. 
Springs are either such as run continually, 
called perennial ; or such as run only for a 
time, and at certain seasons of the year, 
and therefore called temporary springs. 
Others again are called intermitting springs, 
because they flow and then stop, and flow 
and stop again: and, finally, reciprocating 
springs, whose waters rise and fall, or flow 
and ebb, by regular intervals. To account 
for these differences in springs, see Hy- 
DRADLICS. 
Spring, in mechanics, denotes a thin 
piece of tempered steel, or other elastic sub- 
stance ; which, being w'ound up, serves to 
put several machines in motion by its elas- 
ticity, Of endeavour to unbend itself ; such 
Ls the spring of a clock, watch, and the 
like. The spring of a lock, gun, pistol, or 
the like, is a piece of steel, violently bent ; 
which, being set at liberty, beats back the 
bolt of the lock, or strikes down the cock. 
Spring, in naval affairs, a crack running 
transversely, or obliquely, through any part 
of a mast or yard, so as to render it unsafe 
to carry the usual quantity of sail thereon. 
Spring is also a rope passed out of a ship's 
