(470 
. and ratified as to retain but a (mall part of thofe Vapours 
that lliall be brought thither by the Winds. Thofe Va- 
pours therefore that are raifed copioufly in the Sea, and by 
the Winds are carried over the low Land to thofe Ridges 
of Mountains, are there compelled by the ftreamof the Air. 
to mount up with it to the tops of the Mountains, where 
the Water prefently precipitates, gleeting down by the 
Crannies of the (tones and part of the Vapour entring into 
the Caverns of the Hills,the Water thereof gathers as in an 
Akmbick into the Bafons of ftone it finds, which being once 
filled, all the overplus of Water that comes thither runs 
over by the loweft place, and breaking out by the fides of 
the Hills, forms fingle Springs. Many of thefe running 
down by the Valleys or Gutts between the ridges of the 
Hills, and coming to unite form little Rivulets or Brooks : 
Many of thefe again meeting in one common Valley and 
gaining the plain Ground, being grown lefs rapid become 
a River : 'and many of thefe being united in one common 
Channel make fuch ftreams as the Rhine, the Rhone, the 
Danube, which latter one would hardly think the col- 
Je&ion of Water condenfed out of Vapour, unlefs we 
confider how vaft a Trafl: of Ground that River drains, 
and that it is the fum of all thofe Springs which break out 
on the South fide of the Carpathian Mountains, and on the 
North fide of the immenfe Ridg of the Alps, which is one 
continued Chain of Mountains from Switzerland to the 
Black Sea. And it may almoft pafs for a Rule, that the 
Magnitude of a River, or the Quantity of Water it Eva- 
cuates is proportionable to the length and height of the 
Ridges from whence its Fountains arife. Now this Theory 
of Springs is not a bare Hypothecs but founded on Expe- 
rience, which it was my luck to gain in my abode at Saint 
Helena, where in the Night time, on the tops of the Hills 
about 800' yards above the Sea , there was fo ftrange'-a 
condenfetion, or rather precipitation of the Vapours, that 
it was a great Impediment to my Celeftial Obfervations* 
C for 
