purington.] DREDGING. 163 
months in use. New buckets cost $22 landed. The dredge digs on a 
1-inch headline with five-eighths inch side lines, no spuds being used, 
and appeared to dig the gravel very satisfactorily after it was thawed. 
There is not over 2 per cent of the gravel which is over 18 inches in 
diameter. The hull is 71 by 30 feet in dimension and draws -1 feet of 
water; 55,000 feet of Oregon fir was used in its construction. The 
bow and ladder gauntrees are 15 feet high and are built of timbers 12 
inches square. The dredge is operated by steam power. One vertical 
engine of 50 horsepower operates the dredge exclusive of the winches, 
which employ a separate 10- horsepower engine. The boiler carries 
110 pounds of steam and in twent}-four hours burns 3 cords of native 
spruce wood, which costs $10 a cord. The winches are on the star- 
board bow side, the winchman's position being on the lower deck. 
Since the trommel was built its length has been increased and is 
now about 15 feet, with T \-inch holes in the upper plate and 1^-inch 
holes in the lower. The trommel was extended so that none of the 
nuggets, which are worth from $12 to $200, would be lost. The 
trommel distributes the fines to 8 tables, 12 by 30 inches in dimensions 
(see PI. XXIX, A), the distribution being regulated by iron gates. 
The tables, fitted with cocoa matting and expanded metal, have a grade 
of li inches to the foot, and are followed by 2 sluice boxes 20 feet 
long h\ 2 feet wide, with angle-iron riffles, which discharge at the 
stern, as shown in the illustration. An inevitable difficulty with the 
dredge is the banking up of this material at the stern. Three thou- 
sand gallons of water per minute are pumped by a 10-inch centrifugal 
pump. The tables are cleaned up every day; sluices, once a month. 
The season for operating is from May 15 to October 1. It is under- 
stood that the dredge was successfully operated during the season of 
1904 on ground which had been previously drifted. 
The cost of the dredge laid down originally in Lewes River was 
| $125,000. ■ 
A shift sheet used in this dredge, devised by Mr. J. M. Elmer, is 
jhere appended and may be of interest to those engaged in or contem- 
plating dredging operations. 
