54 
DREDGING AT OBAN 
brought to aud from the steamer, and wei’e finally packed for convey¬ 
ing home the selected specimens transferred into spirit. Three 
galvanised iron sieves were also used, having 1^, f, and inch 
meshes respectively. Four tow-nets were taken, 1ft. diameter and 2ft. 
long, one made of coarse muslin, and the others of fine muslin ; these 
were used occasionally, either from the steamer or from a rowing boat. 
When the dredge was lowered it was left each time from ten to 
twenty minutes at the bottom, being either towed very slowly by the 
steamer, or allowed to drift with the current. The rope was hauled in 
by hand over the side of the vessel in raising the dredge ; but a con¬ 
siderable inconvenience was experienced in doing this, from the labour 
of the work and the loss of time involved, about nine minutes being 
generally required for hauling in the dredge, even from the moderate 
depth of 22 fathoms. The provision of some simple hauling winch, 
with a leading pulley for the rope where passing over the side of the 
vessel (however rough in construction), will be an important advantage 
in future dredging operations ; and these should be arranged so as to 
admit of being readily shifted in position, as the circumstances of the 
varying position of the dredge in the drifting of the vessel may render 
desirable. 
A sketch map is appended, showing the localities of the several 
dredging stations ; and an abstract is added of the log that was kept of 
the dredging operations, recording in each case the station, the time of 
lowering the dredge, and the time of remaining at the bottom, with a 
general note of the contents brought up, and the nature of the bottom. 
The most important point of experience gained from the dredging, 
is the great value of the tangles as a means of securing good specimens; 
the large Funiculina specimen was brought up by being caught 
by a few of the hempen fibres of a tangle, and was secured by 
this means in perfect and uninjured condition; and one of the 
two Pennatula specimens was also caught bj^ a tangle. A serious 
defect, however, in the present tangles (which are attached one to 
each bottom corner of the dredge-net), is that the dredige precedes the 
tangles, and the heavy cutting edge at the mouth of the net conse¬ 
quently scrapes over the whole of the ground that is passed afterwards 
by the tangles, and is thus liable to break off and damage objects that 
are growing upright at the bottom of the water. An important illus¬ 
tration of this damage is given by the circumstance that all the 
Virgularia specimens (which have a very brittle and rigid stem) were 
broken off at the bottom, the point of fracture being at a quarter to 
three-quarters of an inch below the lower extremity of the “ feather” 
or fleshy body, and most probably very near the surface of the ground 
in which the objects were growing. 
In the report of the “Challenger” Dredging Expedition special 
value is assigned to the tangles, and as many as eight tangles were used 
together in the dredging, carried by a transverse bar 5ft. long at the 
bottom of the dredge-net, which was 4^ft. wide. A light iron rod was 
attached to each end of the tangle bar, extending to the mouth of the 
