162 



COLLECTING AND CLEANING SHELLS. 



To have a clear idea of the dredge, and the parts which 

 compose it, we must imagine a circular bar of iron, forged in 

 the shape of an almost equilateral triangle, A, B, C, of the 

 above figure, whose two extremities are joined at A. To form 

 the summit or point of the triangle, each of the sides should be 

 above five feet. The two branches, A B, and A C, are rounded 

 and bent, as they approach the base of the triangle. The base, 

 B C, is forged into a plate, six inches in breadth, with a sharp 

 cutting edge in front, turned upwards at an angle of about 

 sixty degrees. The back, or that part opposed to the edge of the 

 plate, is an inch thick. By means of the curvature, b B, c C, 

 fig. 1. and 2., of the two lateral branches, A B and A C, the 

 edge of the plate, B C, is brought forward, and a little turned to 

 the side of the summit. A, as may be seen in the profile of the 

 dredge, fig. 2. A. C. This edge makes, with the plane of the 

 triangle, contained between the straight parts of the two 

 descending branches, A B, A C, an angle of about sixty degrees. 

 There is a large iron rin_^ attached to the summit A ; when, 

 by means of a rope passed through this ring, the dredge is drag- 

 ged along the bottom of the sea, the edge B C, which is turned 



