68 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 
is faulty in this respect. The rope (c, c) forming the upper side of the 
aperture of the net is provided with cork buoys, in order to keep the 
mouth of the net distended. The drag-rope is connected with the bridle 
by means of a stout swivel (a, Fig. 5) so as to allow the rope to twist 
without overturning the trawl. 
THE RAKE-DREDGE. 
Figure 6. 
This instrument was devised in 1871 by the writer* for the special 
purpose of obtaining deep-burrowing species of bivalves, annelids, holo- 
thurians, crustacea, &c. It can be used only on muddy or sandy bot- 
toms, and, of course, requires considerable foree to draw it through 
compact mud or sand. In its original form, which is still in use, it con- 
sists of a strong A-shaped frame, made of flat bar-iron, and so bolted 
together that it can be folded up compactly when not in use, or for con- 
venience in transportation. ‘The rakes consist of two flat bars of iron, 
furnished with strong iron teeth (steel would, perhaps, be better) about 
a foot in length, with thin sharp edges and sharp point. The two rake- 
bars, when in use, are placed back to back and bolted to the ends of the 
side-pieces of the A-shaped frame. The cross-bar of the A projects be- 
yond the side-pieces, and has a hole at each end, by which the arms of 
the dredge-frame are attached, so that the dredge follows the rake at a 
distance of about two feet. The net-frame for this instrument is made 
entirely of round iron, and as light as is consistent with the stiffness 
necessary to support the bagful of mud when being hoisted on deck. 
The length of the frame should be equal to or somewhat exceed that of 
the rake-bars. In the one now used by the Commission it was originally 
considerably larger, but owing to the too great weight of the load of 
mud it brought up it has been made smaller, so that it is now of about 
the same length as the rake-bars. 
The net is similar to that of the common dredge, but deeper and with 
somewhat larger meshes, in order that a part of the mud may pass 
through more rapidly. The vast numbers of annelid tubes, often encount- 
ered in using the rake-dredge, frequently clog the net so as to prevent 
even the fine mud from passing through the meshes. As this form of 
dredge can only be used on smooth bottoms there is not so much need 
of a canvas protection as in the case of the common dredge, and we 
have often dispensed with it, but the net will doubtless last longer if 
protected with the canvas bag. 
* Descriptions and figures (from drawings of Mr. J. H. Emerton, furnished by the 
Fish Commission) of the ‘-rake-dredge,” ‘‘ wheel-tangles,” ‘‘cradle-sieve,” and other 
apparatus used by the Fish Commission were published in 1873, in the New York Tri- 
bune, by Mr. William C. Wyckoff. These were republished the same year in the Tri- 
bune Extra, No. 10, scientific series. They have also been described in several other 
articles. The writer also published a description of the rake-dredge, &c., in an article 
on ‘‘ Deep-sea Dredging” in Johnson’s Cyclopedia, Vol. I, 1875. 
