lO Natirai. History' Billetin. 



useful instrument in deeper water, where the bottom generally 

 consists of ooze or tine mud." In our work we found the 

 bottom down to our deepest dredging, about two hundred and 

 sixty fathoms, almost invariably rock, and the trawl nets were 

 quickly demolished by the severe usage. It is evident that 

 the trawl can safely be omitted from the equipment of a ves- 

 sel, unless really deep dredgings ( say five hundred fathoms ) 

 are to be made. 



The dredges were of two patterns. The •• naturalist's " 

 dredge, for use in shallow water with row-boats or small sail- 

 boats, was made in three sizes, with the frames 15 b}' 6 

 inches. 18 by 8 inches, and 21 b}' 10 inches. The largest of 

 these sizes is small enough for any sail-boat work, and still 

 larger sizes would be better for any but the smallest boats. 

 The '• Blake "^ dredge has the advantage of a frame to j")ro- 

 tect the dredge net or bag. In both kinds of dredges it is 

 necessary to punch a series of small holes around the lower 

 edge of the frame, by means of which the dredge nets can be 

 seized to the fram.es. 



Nets for dredges and trawls can be ordered in any dimen- 

 sions or size of mesh, or in any quantity, of the Gloucester 

 Net and Twine Company, of Boston. Massachusetts, whose 

 long experience enables them to understand the requirements 

 better than any other firm in this country, perhaps.'-^ 



In order to protect the dredge nets, it is necessary to make 

 a canvas bag for each, using good new canvas. (We used 

 second hand canvas, to our sorrow.) The mouth of the bag 

 should be as large as the outside of the dredge frame, to 

 wliich it is securely seized with marline. The bag should 

 be bottomless, so that the \\ater can pass freely through the 

 dredge. It is surprising how soon this dredge covering will 

 be worn out and require renewal. 



At the suggestion of Captain Flowers, we also took along a 



1 Agassiz, "Thtec Cruist's of the IJlakc," page 21, Fip. 22. 



s So much difViculty was oncoiinlt-rcd in fincUnK just where the various items of 

 equipment for marine dredjjing could lie bouj^rht, that the author has decided to be ex- 

 plicit in such matters for the benefit of others wlu> may' desire to secure similar eciuip- 

 ment. 



