258 RESOURCES OF CALIFORNIA. 
now rarely seen, is a wooden trough about twelve feet long, 
eighteen inches wide at the upper end, and widening at the 
lower to thirty inches, with sides eight inches high. It is used 
like a board-sluice, but has no riffle-bars, and at the lower end 
its bottom is of sheet-iron, perforated with holes half an inch 
in diameter. This sheet-iron is turned up at the lower end, so 
that the water never runs over there, but always drops down 
through the perforated sheet-iron or riddle, into a little riffle- 
box, containing transverse riffle-bars. A stream of water of 
about ten inches makes a “tom-head”—or the amount con- 
sidered necessary for a tom—through the tom, which has a 
grade similar to that of a board-sluice. The dirt is thrown in 
at the head of the tom, and a man is constantly employed in 
moving the dirt with a shovel, throwing back such pieces of 
clay as are not dissolved, to the head of the tom, and throw- 
ing out stones. From two to four men can work with a tom; 
but the amount of dirt that can be washed is not half that of 
asluice. The tom may be used to advantage in diggings 
where the amount of pay-dirt is small and the gold coarse. 
The riffle-box contains quicksilver, and as the dirt in it is kept 
loose by the water falling down on it from the riddle above, a 
large part of the gold is caught; but where the particles are 
fine, much must be lost. 
§ 191. Cradle.—The rocker or cradle is still less than the 
tom and inferior in capacity. It bears some resemblance in 
shape and size to a child’s cradle, and rests upon similar rockers. 
The cradle-box is about forty inches long, twenty wide, and 
four high, and it stands with the upper end about two feet 
higher than the lower end, which is open so that the tailings 
can run out. On the upper end of the cradle-box stands a 
hopper or riddle-box twenty inches square with sides four 
inches high. The bottom of this riddle-box is of sheet-iron, 
perforated with holes half an inch in diameter. The riddle- 
box is not nailed to the cradle-box, but can be lifted off with- 
out difficulty. Under the riddle is an “apron” of wood or 
cloth, fastened to the sides of the cradle-box and sloping down 
