DEEP-SEA EXPLOEATION. 
3()5 
The frame A is co]ui)ose(t of two pieces of black walnut, or other suitable wood, 
each 1! feet in length, 2 inches wide, and inch thick, scored ou their iiiuer surfaces 
to receive the rod, springs, and i)eudulum. 
The ba-(;k part of the fraiiiie has a semicircular projection, to which the scale 0 is 
secured. The pendulum B is of brass, 4 inches in lengtli, weigiited with lead at its 
lower end to insure prompt action. There is a disk at its upper extremity with a. 
milled surface, and it is suspended on friction bearings which allow it to swing freely. 
The rod D has a knob on its outer end for convenience in working, and to its inner 
Cut 68. — The angle and scope of the dredge rope. 
grip the milled head of the disk and hold the pendulum securely in place whenever 
the notch in the rod D is freed from the spring catch E. To release it from the em- 
brace ol the spring, press on the knob witli the iialm of the right hand until the notch 
in the rod D is engaged by the slot in the spring catch E; the elliptical spring F is 
thus distended, the friction removed from the disk, and the pendulum given unob- 
structed movement. 
The scale C is of brass, secured to the frame by brass screws; it is graduated on 
both sides from 20° from the perpendicular to 00° or horizontal, so that it can be used 
on either side of the vessel, whether backing or going ahead. A guard of round 
