446 LOGGING 
continued, with proper bracing, until the cut-off height was reached. 
On the 15.75-foot span a block and tackle was used on each batter 
post for elevating the material when the height became too great 
for handing it up. On the 23.5-foot span, lines also were hung 
on the rear bent to aid in raising the 24-foot fore-and-aft braces. 
The cut-off point of the bent was established only when sev- 
eral hundred feet of trestle had been built. A wye level was 
then placed on a staging built on top of a bent and the line of 
levels established by it. The 2- by 6-inch caps were elevated 
and placed in position as soon as the posts were cut off. Cross- 
bracing was put on after several hundred feet of trestle was 
erected (Fig. 160). Bents exposed to the wind were also strength- 
ened by wire guys. 
The construction crew was made up of from six to eight men, 
four of whom worked aloft continuously. On low work one man 
handled and sent up all lumber and another was engaged in 
framing the lower sections. 
The lumber was hauled as near as possible to the point where 
it was to be used, and was assorted and piled where it could be 
reached with the least delay. One man built the boxes in 16- 
or 24-foot sections at the upper end of the flume, placed the 
brackets inside each section, and placed it and the 4- by 6-inch 
stringers and the foot planks in the flume ready to float to the 
front. A man walked the flume and kept the material 
moving. 
Two top men at the front placed the stringers and foot planks 
in position, trimmed the boxes, set them in place, adjusted the 
brackets and nailed them to the boxes. A crew of four men 
placed from twenty to twenty-five 16-foot sections in ten hours. 
This did not include an 8-inch top board on the box which was 
not added until the remainder of the flume box was complete. 
The amount of labor required to erect a flume trestle increases 
rapidly with its height and the wages paid to top workers on high 
trestles also increase with the height above ground. Those 
working at elevations of 75 feet or more may receive from 40 to 
60 per cent more than ground workers. 
The number of days' labor, the pounds of nails and the thou- 
sands of board feet of lumber required to build trestles of specified 
heights and of the types shown in Figs. 160 and 161 are given in 
the Table VIII. The construction of the box and foot-boards re- 
