290 LOGGING 
although short spurs may have ascending grades as high as 6 
per cent for loaded cars, and from 8 to 10 per cent for empty ones, 
and curves as high as 40 degrees, although they should not exceed 
15 degrees under average conditions. 
Geared locomotives, only, are suitable for steep grades and 
sharp curves. The short wheel base permits the locomotive to 
make sharp turns, and increased power is secured through the 
gearing. However, on steep grades and sharp curves a geared 
locomotive can haul only a few cars at one time. 
Methods of Location. — Main line location is preceded by re- 
connaissance work w^hich enables the engineer or logger to de- 
termine the problems which confront him and to select one or 
more feasible routes. In this work a topographic map is very 
helpful and is now considered an essential part of the equipment 
of an operator in a rolling or rough region. Such maps may be 
prepared in connection with a timber cruise, but if not available 
previous to railroad location they are prepared in connection with 
reconnaissance. Contour intervals varying from 10 to 50 feet 
are used depending on the accuracy required and the roughness 
of the country. Relative differences in elevation are of more 
importance than absolute differences, because the logger is chiefly 
interested in the location and height of ridges, degree of slope, 
width of valley bottoms, size and character of streams, and like 
factors which have an influence on cheap railroad construction. 
There is no standard method in use by engineers for collecting 
data for the preparation of topographic maps. The aneroid 
barometer, hand level and pocket compass may be the only 
instruments used, although control points both for distance and 
elevation may be established by chained compass or transit lines 
and a line of "Y" levels run along section or other lines. One 
method used by a western logging engineer on his reconnaissance 
survey, preliminary to location, is to run out and blaze all section 
lines; determine distances by pacing, which are checked on quarter- 
section and section corners; and secure elevations by means of 
an aneroid barometer. A rough topographic map is prepared 
from this data and furnishes a basis for the preliminary location. 
Having roughly determined the route of the road, the pre- 
liminary location follows. The engineer is aided in this work by 
one or two rod men and two or more axmen, depending on the 
density of brush along the route. When an expensive road is to 
