DREBBEL (dreb'bel), CORNELIUS, a Dutch philosopher; born in Alkmaar, Netherlands, in 1572. He invented the Suez Canal was excavated by means of a ladder dredge with a long chute and supporting girder. The material exca vated was carried in boxes on a sort of tramway and tipped out on the bank. The excavating buckets are sometimes placed on the perimeter of a large wheel instead of on an endless chain. The so-called clamshell bucket consists of two parts hinged together which de scend through the water open and re turn closed with its clutch of material amounting sometimes to five cubic yards. In order to work in clay or hard sand it is provided with teeth. In some cases the current of river or tides has been utilized in dredging channels. In bot toms of mud or loose sand the steam pump or hydraulic dredger may be used. Great improvements have been made in hydraulic dredges, and some built in re cent years for use in the Mississippi Liver have a capacity of over 1,000 cubic yards per hour.
Dredging is also the operation of dragging the bottom of the sea in order to bring up oysters, or to procure shells, plants, and other objects for scientific observation. The oyster dredge is a
light iron frame with a scraper like a narrow hoe on one side, and a suspend ing apparatus on the other. To the frame is attached a bag made of some kind of netting to receive the oysters. The dredges used by naturalists are mostly modifications of or somewhat similar to the oyster dredge.
embellished by Augustus the Strong (1694-1736), and rapidly increased dur ing the 19th century. Among the chief edifices besides several of the churches are the museum containing a famous picture-gallery and other treasures; the Japanese Palace (Augusteum), contain ing the royal library of from 300,000 to 400,000 volumes, besides a rich collection of manuscripts; the Johanneum, contain ing the collection of porcelain and the historical museum, a valuable collection of arms, armor, domestic utensils, etc., belonging to the Middle Ages. The royal palace contains (in what is called the