358 LOGGING 



called needle gates, which consist of hewed or sawed 3- by 5-inch 

 or 3- by 6-inch scantlings placed vertically across the opening, 

 thus forming a solid front. The needles are supported at the 

 lower end by a cross-beam or groove cut in the base sill. The 

 tops rest against a cross-beam to which the needles are often 

 attached by short chains. The needles are raised either by a wind- 

 lass, a crowbar or a lever. They are especially serviceable for 

 dams at storage reservoirs through which logs are not sluiced, but 

 where it is necessary to suddenly release large quantities of water 

 in order to carry logs over very rough stretches. In the above 

 case the needles may be hberated by breaking the bottom beam 

 by a charge of dynamite. 



Barn-door Gate. — This consists of one or two heavy gates or 

 doors hung vertically on bearings attached to the sides of the 

 sluice. Double gates are held in place, when closed, by an up- 

 right beam in the center of the sluiceway, and single gates by a 

 similar beam placed on one side of the sluiceway. A horizontal 

 pole is sometimes used instead of an upright one to hold the 

 gate shut. These gates have been used in Pennsylvania and in 

 some parts of the Appalachians, but they are not popular be- 

 cause the force of the water throws them open so violently that 

 they are often damaged. 



A light drop gate is often used to shut off the flow of water 

 while the large gates are being closed. 



LOG CARRIERS 



Loggers operating near the headwaters of streams occasion- 

 ally find it desirable to transfer logs from one water course to 

 another in order to bring them down the stream on which the 

 manufacturing plant is located. 



A log carrier similar to the log haul-up in a sawmill is employed 

 for elevating the logs to the maximum height desired, and a log 

 sluice with a V-box 4 or 5 feet high and 7 or 8 feet across the 

 top then carries the logs into the stream on the other water- 

 shed. Water for the sluiceway is furnished by a series of pumps 

 of large capacity. 



