Titcomb. — Destruction of Obnoxious Fishes 23 



necessitates ascertaining the area and average depth. In 

 sounding for depth it would be well to mark with buoys 

 the deepest places. Note, if possible, any spring holes 

 under the surface of the lake and mark them. Note all 

 possible sources of water supply — even the smallest 

 rivulets. 



Copper sulphate wholesales at around 5% cents per 

 pound and comes in barrels. It should be transferred to 

 bran-sacks or some form of bag of loosely woven material. 

 For rowboats, fifty pounds to a sack is sufficient. For 

 power boats, one hundred pounds is a convenient amount 

 to handle. 



By the use of a 12-foot joist or bar equally strong 

 fastened crosswise of the stern of the boat, a sack may 

 be fastened at each end so that two bags may be drawn 

 through the water by each boat. The sack should be sus- 

 pended at the surface of the water with no more of it un- 

 der water than is necessary to dissolve the contents. 



The copper sulphate should be thus distributed along 

 the entire surface of the lake at intervals not exceeding 

 twelve feet apart and the more quickly it is done the bet- 

 ter. In other words, the more boats that can be mustered 

 into the service the better, with a view to a general, si- 

 multaneous distribution. Each boat should move at about 

 the same pace as that of a fisherman when trolling. 



The deeper portions and the spring holes should be 

 covered more thoroughly than the shallower portions. If 

 a definite boiling spring is found in the lake put a small 

 sack of the material over it so that the water will per- 

 colate through it. 



After the surface of the lake has been covered as 

 thoroughly as possible and as near to the shore as boats 

 can take it, have men on foot drag sacks around the edge 

 of the shore line. Every stream or rivulet must be cov- 

 ered with the material as far up as objectionable fish are 

 known to go. A strong solution of the mixture may be 

 poured into the small streams at intervals with good ef- 

 fect. However, the dissolved copper sulphate precipitates 

 so quickly that there may be conditions in tributary 



