INVESTIGATIONS OF THE ALBATROSS. 259 
7:30 a.m. on the 25th a sounding was made in 1,471 fathoms, green ooze. 
Serial temperatures and specific gravities were taken, and a success- 
ful haul of the trawl followed, the surface net being towed during the 
interval of dredging. 
Submarine tow net.—Experiments with a new design of submarine 
tow net were made later in the day, with unsatisfactory results. In 
fact, it was a failure, owing, doubtless, to the large size of the net and 
its small mesh, which caused undue tension on the bridles while towing, 
The frame is composed of rods and tubing of brass. There is a fine 
serew-thread on the upper half of the central shaft, which works in a 
nut in the upper middle part of the frame. The lower end of the shaft 
is plain and passes through two studs in the frame, which serve as 
stops for the bridies. A propeller on the middle of the shaft holds it 
down while the apparatus is being lowered and. slowly raises it while 
the net is towed through the water. The jaws are of two sizes, 3 feet 
and 24 feet in diameter, with hinges which permit them to open and 
shut. The net is 7 feet in length, half-inch mesh, lined with mosquito 
net for 5 feet, and inside of this lining isanother of silk gauze, extending 
3 feet from the lower end of the net. A weight is attached to the lower 
end of the net to prevent its floating up and fouling the jaws or bridles. 
To use the apparatus, close the mouth of the net, attach both bridles 
by their terminal rings to the central shaft and lower to the desired 
depth, then steam slowly through the water, when the propeller will 
be-brought into action, the central shaft slowly raised, and the first 
pair of bridles released, opening the jaws. After towing about half a 
mile the shaft will have reached its upper limit, when the remaining 
bridle will be released and the net again closed, ready to be hoisted to 
the surface. This apparatus could be made to act by reducing the 
size of the net and removing one of the linings, but the chances of acci- 
dent or irregularity in the working of the propeller were so great that 
there would always be a doubt as to its having properly performed 
its functions. Prof. Agassiz was greatly disappointed at its failure, 
for he considered the examination of intermediate depths among the 
most important problems to be worked out during the cruise. I had 
thought little of the matter, as my confidence in the apparatus just 
described was explicit, but I now set to work to devise something that 
would do the work. 
The Tanner tow net is designed for the collection of pelagic forms at 
intermediate depths, and was used successfully during the cruise. The 
net is the same as that previously described, except that the mosquito- 
net lining is reduced to about half the length of the bag. The upper 
bridle has four legs attached at equal distances around the ring and 
Shackled to a sinker on the end of the steel-wire dredge rope, which 
serves as a tow-line. The lower bridle has two legs, 10 feet in length, 
attached to opposite sides of the ring, and a 60-pound sounding shot is 
toggled on the bight at the lower extremity to act as a sinker. The 
