EXCAVATING MACHINERY USED IN LAND DRAINAGE. 33 
machine making two 4|-foot cuts side by side. The average length 
of ditch cut per day was 800 feet, while the maximum was 1,950 feet. 
The daily cost of operation was as follows : 
Labor $5. 50 
Fuel 4- 20 
Incidentals 50 
Repairs 2. 40 
12.60 
The average excavation per day was 410 cubic yards, based on the 
average of 800 feet of ditch, 4J feet deep, A\ feet wide at the top, and 
20 inches wide at the bottom. The machine excavated 82,330 cubic 
yards in 18 months at the following itemized cost: 
Gasoline based on 215 actual days' operation (estimated) $903. 00 
Repairs, actual cost 860. 00 
Incidentals, at 50 cents per day 120. 25 
Labor of foreman, 18 months, at $75 per month 1, 350. 00 
Other labor, two men, $2.50 per day for 250 days ' 625. 00 
Interest and depreciation 2, 675. 25 
Total 6, 533. 50 
Cost per cubic yard, $0.0793. 
THE HYDRAULIC DREDGE. 
The hydraulic dredge has little application in the construction of 
ditches for drainage purposes, due to the fact that nearly all the drain- 
age ditches are of too small a cross section to be economically dug by 
this method. This type of dredge probably is, however, the most 
economical machine existing for excavating very large channels. 
The essential parts of the hydraulic dredge are a centrifugal pump 
and the power to drive it, the whole mounted on a barge. The 
suction pipe is attached to the pump by a movable joint so that the 
suction end can be raised or lowered. The material, mixed with 
water, is drawn through the suction pipe and discharged where 
desired through a line of pipe sometimes several thousand feet long. 
Coarse sand and gravel, muck, and silt are easily handled in this way, 
and by the use of a rotary cutter on the end of the suction pipe, com- 
paratively hard clay can be removed. The machine does not work 
well, however, where there are stumps, logs, stones, or other such 
obstructions. 
Dredges of this type are suitable for digging ditches 800 or more 
square feet in cross section, for building levees under favorable con- 
ditions, and especially for building up tidal flats and low lands. 
COST OF OPERATION. 
The following table indicates the cost of operating a hydraulic 
suction dredge on the New York Barge Canal in 1908. The dredge 
in question is of modern construction, has a 20-inch discharge pipe, 
