NATURAL HISTORY SOCIETY OF GLASGOW. 181 



to establish the habitat of the animals there found, thus obviating 

 all doubt on that point that might be caused by the dredge being 

 dragged over many hundred yards. 



The body of the dredge is in two pieces, which are held together 

 by the arms passing down through the dovetailing at the sides, 

 and each fixed at the bottom by a screw. The bottom is made of 

 coarse canvas, stretched over a hoop, which fits into the dredge. 

 By these arrangements the whole can be readily taken asunder and 

 packed into very small space. 



Dimensions : 



Length of body, . . . 



Diameter at point of lips. 



Depth of lips, _ _ . 



Longer diameter at lower angle of lips, 



Shorter, do., do., 



Longer diameter at bottom, - 



Shorter do., do.. 



Circumference of arm rods, - 



Weight of dredge, . - - 



The rope is connected to the dredge by ten feet of small chain, 

 which tends greatly to keep down the machine, by counteracting 

 the buoyancy of the rope. The next thing to be taken into 

 consideration is the weight of the dredge. The ordinary weight 

 used for a small boat is about 15 lbs.; but whatever the weight 

 may be, it must be sufficient to take with ease the rope 

 required for its use to the bottom, and to keep its place there 

 against the ordinary speed of the boat, which has a tendency 

 to raise the rope, and with it the mouth of the dredge. When 

 the sea is found a little too rough, or the currents a little 

 too strong, preventing the dredge from taking the ground, a 

 few stones put into it will generally succeed in keeping it down, 

 or a small bag, with a stone, fastened to the rope a fathom or two 

 forward from the dredge, will answer the same purpose, and not 

 interfere with its contents. 



The Rope. — This, of itself, seems to be a trifling matter — yet in a 

 small boat the character of the rope may be of much importance. 

 The first quality is its strength; and as the way on a row-boat need 

 scarcely be taken into account, a rope to resist the strain that 

 could be put upon it by three or four men, may be considered 

 sufficiently strong. A too thick rope adds unnecessarily to the 



