250 A TREATISE ON DREDGES AND DREDGING 



corner and across the back end to a drum which is located about 

 the center of the hull. When it is desired to move the machine 

 the power is turned on to this drum and the chain wound up. As 

 the chain tightens, the hull of the machine rises, the weight coming 

 on the center foot. The winding on the drum is continued until 

 the weight in lifting the hull becomes greater than the friction at 

 the corner feet, when the entire hull moves ahead about 6 ft., although 

 an 8-ft. move can be made. The chain is then released, taking 

 the weight off the center foot, which is pulled by another chain 

 attached to a drum in the front part of the hull. " 



This machine has moved across country at the rate of 1 mile 

 in 11 hrs. The dredge has excavated 7 scrapers of earth and moved 

 ahead 6 ft. 8 in. in 7 minutes. This is said to be an average speed. 

 Difficulty is experienced in excavating in soft material, and also 

 in making short turns with the machine, owing to cave-ins. 



In the same bulletin is described the Junkin ditcher, which 

 consists of a car running on rails, one on each side of the ditch. 

 As in the Austin machine a steel frame extends under and over 

 the machine, and is operated in a somewhat similar manner. 



"At the back of the car, transversely to the direction of the 

 ditch, is a triangular-shaped cutting frame, the lower part of which 

 is constructed to conform to the bottom and slopes of the proposed 

 ditch. Over each half of this frame are two chain belts 30 in. apart, 

 and between these belts are riveted at equal distances 14 buckets, 

 which excavate and carry the material. The cutting edge of these 

 buckets can be detached from the main part for sharpening if occasion 

 requires. The buckets over each half of the frame travel in opposite 

 direction, so that each set passes up the slope of the ditch, where 

 it does the excavating. Their direction is changed at the apex of the 

 triangle by sheaves, each bucket making a complete revolution 

 every 45 seconds, although in easy digging they can run at a speed 

 of two revolutions per minute. The excavating frame can be put 

 together in such a manner that it will cut a narrow or wide bottom, 

 or different slopes. The excavated material is cut up very fine 

 and deposited on either bank. The spoil banks have uniform slopes 

 coming to a sharp edge at the top." 



The dredge excavates a strip 30 in. wide at one time, and as it 

 leaves a ridge in the center of the ditch or canal, after making 

 an advance of 30 ft. it goes back to clean up the slopes and the 

 loose material it leaves. The ridge can be shoveled out by hand 



