[9] VERRILL—DREDGING APPARATUS OF U. S. FISH COMMISSION. 73 
can be taken out and its contents emptied upon the assorting table. 
This also allows the wire netting to be more easily renewed when it 
becomes worn. The upper or coarse sieve (A) is made with wide, flaring 
or hopper-shaped, wooden sides, upon which, at about the middle, there 
are cleats (c, c) that rest upon the edges of the main frame. The bottom 
of the “‘ hopper” is formed of strong galvanized-wire netting, of ?-inch 
meshes (Fig. 13, b, 0). 
Dimensions of table-sieve. 
Inches. 
Main frame, height to upper edge .... . ca IR ay Sag TM oo. Rl par 30 
Ler Mera ES BIT h rare) cee verse Ne Siete chew arereys email tae eal aftestsaeGfala)a 66 
MBit AIS MUTE Leis a gtd oot smh ciay ake eee eee ae ae wee 38 
Mainotrame:widthof side Pi€CeS!..:0.\05 232 As heed ese se slna ae 11 
Main frame, thickness of side pieces’. '...-.....-.-2.5. 2-s.60%----- 1 
Mopper trame,.width of side-piecegs. .2is2\/ie3, 2h akis doas ese ew eee es 13 
sion persirames lene th atsDOttom. is Sete ac a eacle sd arasie sadn 2 oe e 56 
Hopper frame, length at top ......-.... Ege, Sucnaectes Sy Gd circ See ee 66 
Hopper trame, sareadtncat: DObUOMA aAI\. she cs acpee ote S07. 8 Boe ee 27 
Oper iramMe-breadchvat LOP. 2c... ec e sels ce Soe Bae iin eee eat fore Sor 
This form of sieve, in its primary form, was invented by Capt. H. C. 
Chester and the writer, in 1877, but it was soon afterwards much im- 
proved by the addition of the canvas bag and pipe beneath it, which 
were devised by Mr. J. A. Smith, the executive officer of the Speedwell. 
The original use of this sieve was to receive the contents of the trawl, 
instead of emptying it on deck, as had been done previously, but its 
advantages were soon found to be so great that it has also been used 
for washing the contents of the dredges whenever the quantity of mud 
was considerable. The legs are made of unequal lengths to correspond 
with the curvature of the deck. 
EXPLANATION OF THE FIGURES. 
{All the figures are from drawings by Mr. J. H. Emerton.) 
Fig. 1.—The common dredge: a, a, the iron frame; b, b, outline of the net; ¢, c, the 
canvas bag; d, the drag-rope; e, light rope for the attachment of one 
arm. 
Fig, 2.—The beam-trawl: a, a, the beam to which the upper edge of the net is at 
tached ; b, 6, the runners supporting the ends of the beam; ¢, c, the leaded 
line attached to lower edge of net; d, the net; e¢, e, ‘‘ pockets” in the net to 
prevent the escape of fish. 
Fig. 3.—The otter-trawl, showing the mouth of net and side pieces arranged for use : 
a, a, the wooden side-pieces attached to bridle-ropes b, b, by means of four- 
short ropes i, i and 0, 0, of which the pair marked 0, 0 are the shorter; 
d, d, the leaded bottom line; ¢, c, the top line of the dredge-mouth, with 
cork buoys (this should have been drawn shorter and less curved backward 
than the bottom line). 
Fig. 4.—Wooden side-piece of the otter-trawl to show the arrangement of the ropes: 
d, e, rings for the attaehment of the bridle; c, ring for the attachment of 
