_"Bag and Spoon" Dredger._--The first employment of machinery for dredging is, like the discovery of the canal lock, claimed by Holland and Italy, in both of which countries it is believed to have been in use before it was introduced into Britain. The Dutch, at an early period, used what is termed the "bag and spoon" dredger for cleansing their canals. The "spoon" consisted of a ring of iron about 2 ft. in diameter flattened and steeled for about a third of its circumference and having a bag of strong leather attached to it by leathern thongs. The ring and bag were fixed to a pole which was lowered to the bottom from the side of a barge moored in the canal or river. The "spoon" was then dragged along the bottom by a rope made fast to the iron ring actuated by a windlass placed at the other end of the barge, the pole being prevented from rising by a hitched rope which caused the "spoon" to penetrate the bottom and fill the bag. When the "spoon" reached the end of the barge where the windlass was placed, the winding was still continued, and the suspended rope being nearly perpendicular the "bag" was raised to the gunwale of the barge and the excavated material emptied into the barge. The "bag" was then hauled back to the opposite end to be lowered for another supply. This system is still in use, but is only adaptable to a limited depth of water and a soft bottom; it has been largely used in canals and frequently in the Thames. At the Fosdyke Canal in Lincolnshire 135,000 tons were raised in the manner described. According to J. J. Webster (_Proc. Inst. C. E._ vol. 89), the first application of steam power for dredging operations was to a "spoon & bag" dredger for cleansing Sunderland harbour, the engine being made by Messrs Boulton & Watt of Soho, Birmingham. _Dredging by Bucket between Two Lighters._--Another plan of dredging, practised at an early period in rivers of considerable breadth, was to moor two barges, one on each side of the river. Between them was slung an iron dredging bucket, which was attached to both barges by chains wound on the barrels of a crab winch worked by six men in one barge and round a simple windlass worked by two men in the other barge. The bucket, being lowered at the side of the barge carrying the windlass, was drawn across the bottom of the river by the crab winch on the other barge; and having been raised and emptied, it was hauled across by the opposite windlass for repetition of the process. This process was in use in the River Tay until 1833.