256 LOGGING 



persisting until they find one which will connect their two 

 tangents. Three methods are in general use by logging engineers 

 for laying out curves on logging roads; namely, the tangent- 

 offset method, by distance scaled from a map, and by the use 

 of a transit or compass.^ 



On main line work in a rough region, the location survey is 

 followed by a line of levels which furnishes data for a profile map 

 on which the ''elevation of grade " is shown. This is preliminary 

 to making an estimate of the cost of moving earth and rock. 

 The cubic yardage is computed from cross sections- taken along 

 the proposed grade at each station on level or fairly level ground, 

 and at every point where there is a decided change in the con- 

 figuration of the surface. 



BIBLIOGRAPHICAL NOTE TO CHAPTER XVII 



Ellis, L. R.: Necessity for an Accurate Topographic ]\Iap in Logging Opera- 

 tions. Timberman, July, 191 1, pp. 49-53. 



Henry, H. P.: Advantages of Topographic Surveys and Logg.ng Plans. The 

 Timberman, August, 191 2, pp. 65-67. 



Peed, W. W.: Necessity for the Logging Engineer in Modern Logging Opera- 

 tions. The Timberman, August, 1910, pp. 47-49. 



Rankin, R. L.: Practical Topographical Surveys for Building Logging Roads. 

 The Timberman, March, 1912, p. 27. 



Van Orsdel, John P.: Topographic Survey and its Economic Value in Logging 

 Operations. The Timberman, August, 1910, p. 64. 



: How to Obtain the Highest Practical Efficiency in Woods 



Operations. The Timberman, September, 1910. pp. 48-51. 



Wood, A. B.: Accurate Topographic Map is a Good Investment in Logging 

 Operations. The Timberman, August, 191 2, p. 67. 



^ See "Plane Surveying," by John Clayton Tracy. John Wiley and Sons, 

 New York, 1908. pp. 204-208. 



2 See "Earthwork and its Cost," by H. P. Gillette. McGraw-Hill Book Co., 

 New York, 1912. pp. 175-182. "Highway Construction," by Austin T. Byrne. 

 John Wiley and Sons, N. Y., 1902. pp. 447-454. "Theory and Practice of Sur- 

 veying," by J. B. Johnson. John Wiley and Sons, New York, 1901. pp. 438-471. 



