122 GKAVEL AND PLACER MINING IN ALASKA. [bull. 2G3. 
After the ditch line has been surveyed and staked 30 men and k 20 
horses, for example, with plows and scrapers, are put to work. The 
plows proceed ahead of the grader, and the cutting- is continued until 
the uphill side of the ditch bottom is nearly cut to grade. At this' 
stage, which is represented ideally by fig. 20, it will be seen that the 
contents of the cut A, B, C has been thrown up to form the bank 
C, D, E on the outer side of the proposed ditch. The remaining work 
consists in removing the earth in the portion B, F, H, which is par- 
tially uncut and partially built up by the grader. The most eco- 
nomical work is done when the portion removed by the grader is sol 
balanced as to demand the least cutting by the scrapers in throwing 
up the necessary bank. It will be seen from the above statements' 
that the burden of the work falls on the first plows and on the grader, 
though the subsequent work of the scrapers and hand finishing is just 
as important. 
Four horses and 1 man are usually used to a grader, though 8 horses 
are often used. The scrapers use from 2 to 4 horses, depending upon 
Fig. 20. — Section of ditch in construction. 
the size of the ditch. Four horses are not generally used to a scraper 
unless the ditch is to be 7 feet or more wide. The plows breaking 
first ground usually need 4 horses each. It may be said that where a 
slope is steep very little or no cutting is needed on the lower side of 
the ditch, since the dirt necessary for the bank can all be obtained in 
reducing the upper side to grade. 
Special methods are necessary when the ditch passes through sec- 
tions underlain by ground ice, as previously described, or runs over 
sections of rock. Very careful work is needed when the rock is 
broken and fractured. It has been found bad practice to cut through 
the stringy moss which overlies the masses of ground ice, generally 
referred to as "glacier;" in fact it is disastrous to the permanency 
of that section of the ditch, and is the beginning of never-ending 
repairs, since the ice continues to thaw, causing constant leakage. The 
best practice is to build sod walls on the lower side, leaving the moss 
undisturbed. All rock work must be done by hand, and where the ditch 
