CLASSIFICATION AND CAPACITIES OF DREDGES 67 



with a suction dredge of the hopper type known to the writer is 

 250 cu.yds. in 10 hours. This dredge had a 12-in. pump. Other small 

 dredges discharging through pipes show records of sand of about 

 500 cu.yds. From these small records they go up to figures that 

 are enormous. The "J. Israel Tarte," with 36-in. pump, averages 

 from 12,000 to 20,000 cu.yds. per day. The " Francis T. Simmons " 

 has a number of hourly records of 3000 cu.yds. per hour. The 

 "Atlantic and Manhattan," hydraulic hopper dredges with 20-in. 

 pumps, working in the Ambrose Channel, averaged during one season 

 about 9000 cu.yds. in 24 hours or 3700 cu.yds. in 10 hours. The 

 " Galveston " places in its 1400 cu.yd. hopper 1350 cu.yds. in 45 

 minutes. Some records are much higher than these. The largest 

 dredge in the world is the " Leviathan." Working in the Mersey 

 River in England 10,000 cu.yds. of sand was excavated in 50 minutes. 

 This was at the rate of 120,000 cu.yds. in a 10-hour day. This 

 dredge can excavate to a maximum depth of 70 ft. 



