10 J. LeConte on the Silver-Spring in Florida. 
country is quite undulating or rolling,—the summits of many of 
the hills being 30 or 40 feet above the adjacent depressions,— 
yet, there is no surface drainage: there is not a brook, rivulet, 
branch, or swamp to be found in this part of the State. The 
whole drainage is subterranean: even the water which falls 
near the banks of the Silver-Spring passes off by under-ground 
channels. There is not the slightest doubt, but that all of the 
rain-water which falls on a large hydrographic basin passes down 
by subterranean channels, and boils up and finds an outlet to 
the St. Johns river, by means of the Silver-Spring and the smaller 
tributary springs which occur in the coves along the margin 0 
the stream. The whole surface of the country in the vicinity of 
Ocala,—and probably over the area of a circle of 15 miles radius 
whose centre is the Silver-Spring, is thickly dotted with lime- 
_ sinks; which are the points at which the surface water finds en- 
- trance to the subterranean passages. New sinks are constantly 
occurring at the present time. ‘The beautiful miniature lakes, 
—whose erystal waters are so much admired,—which occur in 
this portion of Florida, are, doubtless, nothing more than exten- 
sive lime-sinks of more ancient date. 
Under this aspect of the subject, it is obvious, that all the wa- 
ter which falls on this hydrographic basin boils up in the Silver- 
Spring, after having been strained, filtered and decolorized in 
its passage through beds of sand and tortuous under-groun 
channels. It thus comes out not only entirely free from all me- 
ane 
mentioned conditions, which persistently secure the waters of 
this Spring from the admixture of insoluble materials as well 
tion must be comparatively small. 
