DEEP-SEA EXPLORATION. 
361 
lu selecting’ material for lead ropes, particularly for the Blake deep-sea trawl net, 
better results will follow by using rope that has been a short time iu service, as a 
tackle fall for instance, until the extra turns are taken out of it end it has become 
pliable and well set. Condemued running rigging has been used, but it is not recom- 
mended, owing to its uncertain strength. The iiractice of bending trawl nets to their 
frames as soon as they are roped and tricing them up while the 
side seams are being laced and pockets and jackets attached 
is recommended, as the finished net invariably sets better when 
so treated. 
A trawl net should set very loosely on its frame when dry, 
for if it fits snugly then its shrinkage when wet will be sufficient 
in most cases to impair its usefulness. 
The net length is given for head, leech, and lead roxies, 
no allowance being made for shrinkage by wetting, as that 
depends largely upon the roxie used. 
THE DREDGE. 
The dredge iu ordinary use on shix^board is shown iu cut 
65. It is com])Osed of a x>idi‘ of beveled jaws flaring about 12 
degrees and joined together by an iron stud at each end, -which 
is welded to the jaws. The net is laced through holes along 
the back edges of the jaws, and x>rotected from chafing on the 
bottom by a canvas shield wddch is drawn over it and laced 
through the same holes. 
Iron arms serve as a bridle. One arm is a little shorter 
than the other and is secured to the larger one by a seizing 
which is intended to x>art whenever undue strain is brought 
uxiou it, allowing the dredge to be drawn ux) by one arm, in 
which x'osition it would be most likely to free itself from an 
obstruction. Its dimensions are as follows: 
Jaws: Length, 2 feet; width, 2X inches; opening between, 8 inches; 
angle of 12 degrees. 
Stud: Length, 0 inches; diameter, round iron, J inch. 
Bridle: Diameter, round iron, f inch; weight of metal part, 26 
pounds. 
Net: Length, .3 feet 6 inches; size of mesh, square, 1 inch; material, 
cotton, harked, 30-thread; jacket, length, 2 feet 6 indies; jacket, 
size of mesh, inch; jacket matt'rial, cotton, harked, 16-thread; 
hottom lining, cheese-cloth. 
Shield : Length, 3 feet 8 inches ; material. No. 2 cotton c.anvas. 
Cut 65. — The common 
dredge. 
THE CHESTER RAKE DREDGE. 
This admiralile instrument (cut 06) was devised by Oafit. II. 0. Chester for the 
purpose of collecting mollusca., annelids, Crustacea, etc., which burrow beneath the 
surface out of reach of any other ax)paratus in use on board vessels of the U. S. Fish 
Commission. The rake is shackled to the dredge roxie, and a Blake dredge secured 
to eyebolts on the rear of its frame, follows it as it is dragged over the bottom, and 
