354 



LOGGING 



SLUICE GATES 



It is necessary to provide some form of gate for controlling 

 the water in the sluiceway. The more common type is a lift 

 gate the width of the sluice. It slides up and down in a groove 

 formed by two heavy timbers nailed on each side of the sluice 

 walls, which are far enough apart to allow the gate to work up 

 and down easily. The gate may be lifted by levers, by a ratchet 

 device or by a windlass operated by levers. 



Fig. ioo. — The Upstream Ivux- ol a Small kaltcr I) 

 Form of Lift-Gate. 



Bear-trap Gate. — This type of gate has been used frequently 

 in Pennsylvania. The chief features are two rectangular leaves 

 each of which has a length equal to the width of the sluice. 

 They are fastened to the bottom of the sluice by hinges on which 

 they turn. The upstream leaf overlaps the downstream one 

 when the leaves are down and the gate open. 



The gate is raised by the pressure of water from the upper 

 pool, which is conveyed in a channel, controlled by a sluice 

 gate, to a chamber {A), Fig. loi, constructed under the gate. 

 A second channel, also provided with a gate or stopcock, con- 



