POWER SKIDDING 221 



facilitate the passage of the logs. On a i-mile haul one engine 

 can handle daily the output from two yarding engines, or from 

 90,000 to 100,000 feet. 



Dudleys. — On grades too steep for locomotives a special type 

 of locomotive known as a "Dudley" or "Dudler" (page 301) is 

 often used, either to drag the logs over the ties or to haul log 

 cars up or down steep grades. 



BIBLIOGRAPHICAL NOTE TO CHAPTER XIV 



Berry, E. J. : Advantages Accruing to the Adoption of Electricity in Logging. 

 The Timberman, Portland, Oregon, August, 1912, pp. 32-33. 



Cole, C. O.: Difficulties Confronting Electric Log Haulage. The Timberman, 

 August, 1912, pp. 36-37. 



HiNE, Thomas W.: Utility of the Duplex Logging Engine and the Duplex 

 System of Yarding. The Timberman, August, 1910, pp. 36-37. 



Kalb, Henry A.: Utilization of Compressed Air for Snubbing Logs. The 

 Timberman, August, 191 2, p. 53. 



Mereen, J. D.: Substitution of Electricity for Steam in Modern Logging 

 Operations. The Timberman, August, 1912, pp. 29-30. 



Thompson, Jas. R.: Use of Electricity on Logging Operations. The Timber- 

 man, August, 1910, p. 64L. 



Williams, Asa S.: Logging by Steam. Forestry Quarterly, Vol. VI, No. i, 



PP- ^-iz- 



