OPEN DRAINS. 1 73 



stations are computed, enter the results in the note- 

 book opposite the respective stations, and in the column 

 headed for that purpose. 



Ditching with Steam Dredges, 



As large ditches can be made more profitably with 

 the steam dredge than by any other means, a brief de- 

 scription of the working of these machines is here given. 



There are two general types of dredges used for this 

 work, differing mainly in the way they are moved over 

 the line of the work. One is the float dredge, in which 

 the machinery is mounted on a float boat, the engine 

 in the rear and the turn-table and excavating machinery 

 at the front. The excavator is in the form of a large 

 dipper holding from \ yard to if yards, according 

 to the size of the machine, and is operated like an 

 ordinary river dredge. The dipper is lowered to the 

 bottom of the ditch in front of the boat, filled, then 

 raised and swung to one side, and the contents dropped 

 by tripping a latch which allows the bottom of the dip- 

 per to fall. The boat is prevented from tipping over on 

 its side when the loaded dipper is swung by strong 

 braces with feet, which reach to the bottom or rest on 

 the bank of the ditch. As the excavation proceeds, 

 the boat is made to float forward as fast as desired. 

 The excavation is done under water, the depth of the 

 ditch being gauged mainly by the height of the water 

 on the dipper handle as it descends into the water to 

 be loaded. A necessary attendant of the dredge is 

 the floating boarding-house which follows a few hundred 

 feet in the rear. This is . fitted up with kitchen, 



