TRANSACTIONS OF SECTION G. 755 



itself is wbown to be due to the ever-varyinfj motion of the particles of water as 

 they move along the channel, the numerous whirlpools and eddies caused by irregu- 

 larities in the contour of the channel giving a rotary and upward motion which 

 prevents the particles of matter in suspension from being deposited. The power of 

 water to transport solid material depends on the velocity which governs the trans- 

 porting power m two ways: one certain, when, the quantity of water being constant, 

 the amount of material carried will vary directly as the velocity, and as affected 

 by the time that gravity has to act on the particles while travelling a given dis- 

 tance ; the other uncertain, and being due to the increase of eddies and whirling 

 motions set up by the increased momentum of the stream. Also depending on the 

 fineness of the particles and the specific gravity of the material in suspension. 



A table is given showing the results of experiments on the weight of different 

 kinds of clay, sand, and warp ; the time taken to deposit in water ; and the quantity 

 transported by a stream of water running at the rate of one foot per second. 



The second part of the paper deals with the practical application of the process, 

 and several instances are quoted of its successful adoption. The pi'ocesses described 

 are harrowing; scouring caused by the use of artificial dams attached to barges; 

 forcing water and air into shoals and sand-beds by pumps worked by steam power ; 

 also pumping up the material and delivering on to the surface of the ebbing 

 current; and breaking up beds of clay by means of revolving rollers drawn along 

 the bed of the stream. 



The process has been successfully applied to the deepening of rivers in the Fen 

 District, at a cost very considerably under that by which the improvement could 

 have been eflected by the ordinary method of dredging ; and at Tilbury Dock the 

 cleansing of the tidal basin is now carried out at one-fortieth of the cost that used 

 to be incurred in removing the deposit by dredging. 



As the successful application of the process depends on the thorough disinte- 

 gration of the particles to be moved by continual stirring or churning, the author 

 has, alter numerous trials, designed an improvement on existing machines, which, 

 while breaking up and disintegrating shoals composed of clay, sand, or warp, at 

 the same time thoroughly mixes the material with the water, allowing it to be 

 effectively transported by the ebb current clear of the channel to be improved. 



3 c 2 



