SOME FLORIDA' LAKES AND LAKE BASINS. G9 
Solution in the limestone occurs both above and below the water 
line, but chiefly above. As solution continues the overlying ma¬ 
terial is no longer able to support its own weight and caves in, form- 
, ing a sink or natural opening from the surface to the limestone. As 
long as this sink remains open, water passes through and escapes 
readily into the limestone. Drilled or dug wells serve as artificial 
openings to the same formation. Wells drilled into this limestone 
will serve either as supply wells from which water may be pumped 
or as drainage wells into which water may be conducted. It is 
generally the case that a well entering this formation that can not 
be appreciably affected by pumping, will also conduct water readily. 
If the openings at the mouth of the well are sufficiently free to per¬ 
mit ready flow to the well when being pumped, they are, converse¬ 
ly, sufficiently open to allow the water to spread rapidly from the 
well when used as a drainage well. The amount of water held in 
the pores and cavities of the limestone is so* great that the water 
level is not appreciably affected either by the water removed when 
a well is being pumped, or by the water added when a well or sink 
is used for drainage purposes. 
Attempts to enlarge existing sinks or to re-open sinks that have 
become clogged have usually proved futile. It is doubtless true that 
the opening through sinks is a more or less winding channel and to 
re-open this when clogged with debris is' difficult. 
Better success has been obtained by dug or drilled wells. Where 
the underlying porous formation into which the well is to be drained 
lies near the surface, dug wells can be used to advantage and may 
be preferable. Dr. H. Bjystra has used this method in draining a 
small lake or “prairie’'' on his farm near Brooksville, Florida. At 
this locality the cavernous limestone lies near the surface and is 
reached by relatively shallow wells. The one difficulty experienced 
as reported by Dr. Bjystra is the fact that during the summer rainy 
season in one or two instances the rainfall has been so heavy within 
a short space of time that the wells were unable to carry away the 
water as fast as it fell, the result being temporary overflow of the 
farm and serious injury to growing crops. It is probable that this 
danger can be removed in this instance by digging additional 
wells. 
Drilled or bored wells have been in some instances notably suc¬ 
cessful. An advantage in the drilled well is that it can be put 
down to any required depth. When properly cased and screened 
drilled wells are permanent. The effectiveness of the well is de¬ 
pendent upon the structure of the formation penetrated. If the 
water-conducting power of the formation reached by the well is 
