24 
and the other the waste water from the mines which is allowed to run 
off where it will.as long as it does not contaminate the other source. 
There are a few sink-holes in the west part of Herrin, also characteristic 
of a mining area because they are probably caused by the sinking of the 
ground over a part of the mine which has been worked out and aban- 
doned. Just to the northwest of Herrin is a woods swamp, which in 
rainy seasons covers an area of about half a square mile. Low, swampy, 
wooded areas are fairly common in the mining sections of Williamson 
and Franklin counties; and in this case the water in the swamp is kept 
replenished by waste water from the mines. 
In going carefully over the town and the territory immediately sur- 
rounding it I found eight breeding places, or series or types of breeding 
places—including those | have classed as domestic—from which the mos- 
quitoes to be found in Herrin might be expected to come. All but the 
latter class are numerically indicated on the accompanying map, and a 
brief characterization of all of them follows: 
