18 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. 
On the under side is a cog rack which moves over pinions mounted 
on the upper side of the boom. The handle must be of sufficient 
stiffness to prevent bending when the dipper is being filled. 
The method of attaching the dipper to the lower end of the handle 
is practically the same for all sizes of dredges; the connection is made 
by means of castings, pin-connected to the back of the dipper, so that 
the pitch of the dipper may be changed to suit the kind of material 
excavated. 
On dredges ordinarily used in drainage work the dipper or bucket 
varies in size from three-fourths to 4 or 5 cubic yards. The dipper 
varies somewhat in shape with different manufacturers. For work 
in ordinary material the cutting edge is made of a single steel plate, 
preferably manganese steel; but if the material is hard, large steel 
teeth are used to reinforce the cutting edge. The bottom of the dipper 
is a heavy steel plate, which is hinged to the back and held in place 
by a spring latch on the front of the dipper. The latch is operated 
by the craneman, who thus dumps the contents of the dipper. The 
bottom is so hinged that as the dipper is lowered into the ditch the 
weight of the bottom causes it to close and latch automatically. 
The larger the dipper used the larger must be the engine and boiler 
and, in fact, all of the parts, including the hull. Thus the size of a 
dipper dredge is determined by the capacity of its dipper. Table 7 
gives the dimensions, weights, and approximate prices for the various 
sizes of dippers. 
TABLE 7.—Dimensions, weights, and prices of dippers. 
| 
Capac-| tnside Inside Inside Approxi- 
ity of | | oath top bottom | Height. | Weight. mate 
bucket.| ““"8"7* | width. width. price. 
Cu.yds.| Inches. | Inches. | Inches. | Inches. | Pounds. 
28 7 
4 303 312 27 1, 725 $500 
3 314 343 353 30 2° 700 690 
1 34 403 413 35 3” 450 810 
14 40 43h 443 37 4 600 955 
2 43 48 49 42 7,100 1,325 
Qh 44} 52 52 46 | 11,500 2'170 
3 48 56 57} 50 | 12,975 2? 330 
4 53 583 60 53 | 14,025 2’ 550 
5 54 66 663 ts isptelapis| Pal eo 
ACCESSORY EQUIPMENT. 
To keep a floating dipper dredge in operation barges must be pro- 
vided for transporting the fuel to the dredge. These barges are 
generally towed by launches. The fuel barges and the hull for the 
launch are built at the time the dredge is assembled. The launches 
are propelled either by a screw propeller or a paddle wheel driven by 
an internal-combustion engine of from 8 to 12 horsepower. 
House boats with either a one-story or two-story superstructure 
inust be built as living quarters for the dredge crews. ‘The one-story 
