COLLECTING SHELLS. 213 



attached, as we have said, one end to the back plate B C, 

 and the other to the transverse rod or bar h c. 



This rod must be firmly fixed in its place ; for this pur- 

 pose, it is a little flattened, and pierced in its middle, D, 

 with a hole. A bar, A D, figs. 1 and 2, which comes from 

 the summit A, of the dredge, and which is also flattened and 

 pierced with a hole at its extremity, D, is joined, by means 

 of that extremity, to the middle of the rod, b c, on the con- 

 cave side, so that the two holes are adapted to each other. 

 The extremity of a small cross bar of iron, D/, is made to 

 pass these, which issues by the other side of the rod, b c, 

 and the bar, A D. The same cross-piece of iron, D /, is 

 attached, in a similar manner, by its other extremity, /, 

 which is made to pass, that it may be afterwards bent, 

 through one of the holes, with which the back of the plate, 

 B C, is pierced. 



This plate, as we before mentioned, is pierced with eleven 

 holes, of which eight only are employed in giving passage to 

 the meshes of the net or bag. These holes are arranged two 

 and two together : an idea of their arrangement, and the use 

 of the three others, may be learned by inspecting fig. I. That 

 in the middle serves to attach the cross-bar D/. The two 

 others serve to attach in like manner, two similar cross-bars, 

 d d, d d, fig. 1, which strengthen the whole machine, and of 

 which the other extremity is attached to the rod, 6 c, by a 

 kind of hook which embraces that rod. 



The bar, A D, and the cross-bar, D/, are inclined to one 

 another. By means of this inclination, the bar A D, through 

 which passes the cross bar T> f, is strongly fixed to the rod 

 b c, from which it can be removed only by being elongated. 

 This bar, A D, is a little less thick than the two ascending 

 branches A B, AC; they are, however, nearly two inches 

 in diameter. The three branches, A B, A C, A D, unite 

 again at the summit of the dredge, where they are welded 

 together so as to make only one, whose extremity is bent to 

 embrace the ring, as seen at A, figs. 1 and 2. The common 

 oyster-dredge is smaller than that which we have described, 

 and of a lighter make. 



