24 FOREST UTILIZATION 



The usual splash dam consists of timber cribs filled with 

 rock and joined by logs laid crosswise. The front of 

 the dam must be slanting and is covered with a double 

 layer of boards. The gateway of the dam must allow 

 of rapid drawing (or opening) of the basin. The gates 

 are either constructed barn door fashion, held in place 

 by a strong key and lever, or consist of (vertical) 

 piling, the individual piles to be lifted by a crowbar' or 

 drum. Half-moon-shaped gates are used in the Lake 

 States and in the Adirondacks. 



The smaller the water supply and the greater the pressure 

 the tighter must be the gate. 



The expense of a splash dam of the first order is from 

 $i,ooo to $2,coo. A timber splash dam lasts from' six to 

 ten years. 



Frequently additional small gates are made to give a 

 "fore-water," meant to loosen the logs in the creek 

 below the dam. The actual splash rather presses the 

 logs down the creek, instead of floating the logs. 

 II. Dams in the creek, bed itself are sometimes required to 

 raise the water in a shallow section. 



III. Before driving begins, the creek bed must be cleaned out 



by removing old log jams, leaning trees and huge 

 boulders. Sharp bends of the creek must be cut 

 through, so as to straighten the creek bed. ^ 



IV. Fixtures along the bank of the creek are required to pre- 



vent logs from getting smashed when striking a bluff; 

 from being thrown on the bank in a curve of the creek ; 

 from destroying the banks, and further to prevent the 

 spread of water and loss of force, where a splash is 

 expected to overrun adjoining flats. 



Such bank fixtures consist of: 



Pole cribs filled with rock, the poles lying solid, pole to 

 pole, toward the creek, or of inclines of poles laid 

 horizontally, supported by "Strong uprights from be- 

 hind, or of alternating layers of fascines and stone, 

 joined together by strong piling driven into the ground; 

 or, finally, of brush laid on the sloping bank and irreg- 

 ularly covered with rock. 

 V. The bottom of the creek is sometimes paved with stone 

 or poles laid lengthwise, where the bottorh consists of 

 clay. This is especially necessary in artificial channels 

 or canals dug through sharp curves of the creek, or dug 

 close to the connecting booms. 

 VI. Booms. 



(a) European booms are rake booms, the teeth of the 

 rake formed by strong palings. 

 The tops of the teeth are connected by strong 



