DESCRIPTION OF THE EXPEDITION. 17 
used nineteen dredges, and, in spite of the constant exertions of the blacksmith, had on 
arrival in the Seychelles only four fit for use; but then, as already mentioned, our aim 
was rather to ascertain the nature of the bottom around coral-reefs than to preserve our 
instruments. Under no circumstances can we recommend the galvanized frames, as the 
process weakens the steel and flaws are less apparent. 
The trawls employed were of one pattern only, a modification of the well-known 
Agassiz trawl, used for the first time, we believe, by ourselves. The Agassiz trawl is 
derived from the beam and consists of two stirrups joined together, top and bottom, by 
Fig. 4. 
s+ 
a. 
Ekhman Current Meter. 
A, double yane; B, propeller; C, first messenger, which has pushed out D so that E no longer catches the 
propeller; F, measuring-dials over the compass; G, ball-and-socket joint on which the meter swings freely. 
bars. Its particular merit lies in the fact that it is immaterial upon which side it falls. 
It is also particularly convenient for transport, since all its parts, being bolted, can readily 
be taken asunder and put together. Its weakness lies in the bars joining the stirrups, 
which readily become bent or broken. Our modification consisted in attaching the bag 
on either side not to the bottom angles of the stirrups, but two-thirds up their sides. We 
then made the ground-ropes considerably longer, and to prevent the upper falling on the 
lower and closing the bag coarse netting was stretched between the upper and lower 
bars joining the stirrups. This also served in some degree to prevent strong swimming 
forms from getting out of the mouth of the net as its upper half was closed. It will be 
SECOND SERIES.—ZOOLOGY, VOL. XII. 4 
