WATER SUPPLY OP PASTERN AND SOUTHERN PEORlDA. 151 
failure of which was unusually rapid, Slichter says: “This basin 
was discovered in 1884, and in a few years about 400 wells had 
been drilled within an area extending a distance of 40 miles, 
along South Platte River, in a strip about 5 miles wide on both 
sides of the stream. Most of the wells were within the limits 
of the city itself. Many of the wells had a good pressure and 
strong flow when first constructed. In 1886 it was not thought 
that any general decrease in the flow of the wells could be 
detected. Between 1888 and 1890, however, a continuous decrease 
in the flow of the city wells took place, and by the end of the 
latter year all but six of the city wells had to be pumped, while 
numerous wells in the basin were permanently abandoned.” 
CAUSE OF THE BOSS OF FLOW. 
The loss of flow may be due to several causes. It is frequently 
the case that the life of an artesian well is limited. The escape 
of water through the well relieves the pressure, which results in 
a reduced flow. In some instances, pressure has so far been 
relieved that wells have ceased to flow entirely. This may be 
regarded as a natural and unavoidable loss of flow. 
The second cause of reduced flow, which may have affected 
the Jacksonville and other wells, is interference of wells. Num¬ 
erous instances are on record where one artesian well has 
affected surrounding wells. 
A third possible cause is clogging of the wells through 
accumulation of sand or other material in the pipes, or in the 
formations through which the water comes. In addition to the 
accumulation of sand, it is not impossible that the porosity of the 
formation immediately around the well may have been more or 
less affected by chemical deposition since the well was drilled. It 
seems probable, however, that the clogging of the pores of the 
rock is more likely to be caused by material mechanically trans¬ 
ported than by chemical deposition. 
Improper casing is likewise a frequent cause of failure. It is 
frequently the case that an insufficient length of casing is used in 
the well. In such cases the sand gains entrance, or the well 
