156 LOGGING 
cent. The graph indicates that the gross hour output on bare 
ground in summer is greater than on a snow bottom of from 10 
to 20 inches for distances of a few hundred feet, while for long dis- 
tances a snow bottom is more efficient. Undoubtedly this is 
due to the greater effort required to break out snow trails for 
the short distances and the tendency to take maximum loads 
only on the longer hauls. 
The effect of gradient on the output when skidding is done on 
a snow bottom is shown in Fig. 37. This graph indicates that 
the gradient has less influence on output on snow bottom than 
on earth bottom, although the tendencies are similar. The 
greater efficiency on the steeper slopes begins at about the same 
distance as for summer logging, but on the long hauls the effect 
of grade on output is less with snow bottom than with earth 
bottom.^ 
When skidding with two animals, either horses or mules, and 
handling timber that averages from six to nine logs per thousand 
board feet, a day's work, ten hours, ranges between 10,000 and 
15,000 board feet for distances up to 500 feet, A daily average of 
10,000 board feet during a month is considered good. For a 
distance of 750 feet the average ranges between 8000 and 12,000 
board feet and for 1000 feet, from 3000 to 4500 board feet log 
scale. A two-yoke team of oxen will average approximately 
the same number of board feet per day as a pair of mules or 
horses. 
BIBLIOGRAPHICAL NOTE TO CHAPTER X 
GiRARD, James W. : Inland Empire Sawing and Skidding Studies. Timber- 
man, Sept. 1920, pp. 36 to 38. 
Grainger, M. A.: Woodsmen of the West. London, E. Arnold, 1908. 
Margolin, Louis: The Hand Loggers of British Columbia. Forestr}^ 
Quarterly, Vol. IX, No. 4, pp. 562-567. 
1 See Fig. 35. 
