4 WALLICH, ON APPARATUS FOR DREDGING, ETC. 
the rod or cylinder, and at the centre of the margin of this 
plate, intended always to rest on the bottom, is attached a 
stud of several inches in length, whereby the moment contact 
with the surface of the ground is made the plate is made to 
rise and admit whatsoever presents itself. ‘To complete the 
apparatus, a twelve- or fourteen-pound lead weight is cast 
round the upper portion of the knee formed at the angle 
of the rod; a small rod of iron, about eighteen inches in 
length, is riveted at the outside of the mouth of each cylinder. 
This rod is bent somewhat backwards, its use being, in event 
of the cylinders touching the bottom in a lateral direction, to 
tilt them forward again. Lastly, the line being attached, the 
apparatus is ready for use. 
In sounding, it should be hove astern as far as possible. 
Now it will be observed that, owing to the angle in the iron 
rod, and the heavy weight appended to a particular part of 
it, whilst in the act of sinking such weight will remain per- 
pendicular, whilst the cylinders will be held out from the 
perpendicular to the extent of the angle. They will never- 
theless touch the bottom first at their outer closed ends, 
which will then act as a fulcrum, on which the rod will turn 
till it also reaches the bottom. The line bemg now hauled 
upon, each cylinder acts as a scoop, and on leaving the 
surface is effectually closed up by the return of the valve to 
its normal position. 
Of course soundings with this apparatus, or indeed with 
any apparatus, can only be effected in perfectly calm weather 
or at anchor, its advantage over other forms consisting in 
its simplicity, its certain action, and the great quantity of 
material it is capable of bringing up. No doubt it admits 
of mechanical improvements in many ways, and these could 
with ease be carried out; but as the organisms found at the 
sea bottom are daily engrossing more attention, whilst those 
procurable near the surface are not only interesting in them- 
selves, but can be made to yield up the minute ‘structures 
they feed upon, and from which the microscopist eliminates 
many a choice repast, I trust the foregoing detail may not 
prove without interest. 
