76 Report of the Board of Shell Fish Commissioners, =<" 
Tt consists in a drag made up of three pieces of chain — 
fastened to the middle and ends of a wooden bar two feet in — 
length, to which by means of a short wire bridle a stout cop- — 
per wire is attached. To this wire, near the point where it — 
passes to a reel on the launch, a short stiff wire is joined by — 
means of a clasp, which leads to a cone-chaped bell having — 
a universally jointed clapper with adjustable disk fastened — 
to the roof of the launch. When running a line of soundings — 
the drag at the end of the stout wire is towed over the bot- 
tom, and from the vibrations or lack of vibrations on the 
wire the condition of the ground is inferred. The vibrations 
are detected by the hum of the disk in the bell or by holding — 
the wire in the hand. When the drag is passing over barren 
bottoms the chains tow smoothly and evenly and no vibra- 
tions are transmitted to the wire, but when shells or oysters 
are struck by the chains the wire is made to jerk and vibrate. 
If the vibrations are infrequent the inference is that shells” 
or oysters are very scattering and when the vibrations be-— 
come more frequent or constant a scattering, medium or dens 2 
growth of oysters is inferred. eZ 
A small boat containing small buoys with 10-pound dumb- 
bells for sinkers is towed behind the launch at a distanee 
such that it remains above the chain drag. At points on 
each line of soundings small bouys are cast over to mark 
stations to be occupied and examined by the ‘‘INVESTI- 
GATOR” which, with an expert tongman, follows the survey 
launch (see insert opposite page 16). The position of each — 
buoy on the line of soundings and the number of each is: 
recorded in both the angle record and sounding record be ks. 
Their positions are also plotted on the boat sheets, being 
indicated by small flags (see page 77). a 
Between consecutive plotted positions of the launch in a: 
line of soundings, shown in figure 8 by the numerals above 
the lines (32-41), seven observations of the depth of wa er, 
character of the bottom and condition of the oyster ground 
have been made. The positions of these observation stations 
are plotted on the lines of soundings by dividing the part of 
the plotted line between consecutive positions of the launch 
into eight equal spaces, the points separating these spaces 
indicating the positions of the sounding stations. The find- 
ings of the local assistant with the chain apparatus at these 
stations are indicated by writing the symbols B, V, 8, 8, M or 
D below the lines as shown in figure 8. De 
