APPLIANCES FOR COLLECTING PELAGIC ORGANISMS. 
147 
Describing tlie apparatus, Agassiz says (Bulletin of the Museum of Com))arative 
Zoology, vol. XXIII, No. 1): 
Fig. 1 shows the closed net ready to lower; fig. 2, the net opened, ready to tow at the required 
dej^th; and fig. 3, the closed net on its way up. /is the metal frame protecting the propeller j). The 
propeller shaft extends to the cross bar c", fitting into a socket from which it is relieved after a few 
trims of the propeller, when the net is first moved horizontally, and liberates the rings of the chain h 
from the bar c", and thus opens the jaws of the net, bringing the strain on the two parts of the chain 
a. As soon as the propeller shaft passes beyond the crossbar c, the upper parts of the chain « are 
relieved, and it then becomes the longest, and the strain comes upon the chain h, which pulls together 
and closes the jaws of the net at the termination of the time of towing, and it remains closed until it 
reaches the surface. 
The net was -^-iiich mesh, thread 34-0 stow, barked, lined with mosquito net the 
entire length, with an inner lining of silk gauze in its lower half. 
The apparatus was tested on the 35th of Feliruary, 1<S91, when it was towed near 
the surface, where every detail of its action could be noted, this iirecaution having 
been taken merelj" as a matter of form, as our conhdence in the device was explicit. 
Tt was soon apparent, however, that the propeller would not act at all under the low 
speed required with the tine-mesh net of delicate material needed for our purpose, and, 
increasing the speed sufflciently to work, the propeller iiroperly, the strain on the parts 
was so great that no dependence could be put upon its uniform action. 
THE TANNER INTERMEDIATE TOW NET, FIRST PATTERN. 
This element of uncertainty being inherent in the system, we decided to abandon 
it and seek for some method more direct and positive in its action, I had thought very 
little of the matter, having perfect faith in the Ohun-Petersen device; but, seeing the 
disappointment of Prof. Agassiz and knowing how important he considered our con- 
templated exploration of intermedial depths, I set about devising an apparatus for 
its accomplishment. Taking the ring and net of the Chun-Petersen apparatus, we 
removed the mosquito-net lining from the upper portion of the latter, and added a 
bridle having four legs of equal length which were secured around the ring in such a 
manner that it would remain oi)en at all times. 
The steel- wire dredge rope, which served as a tow line, was attached to the bridle 
by a shackle; 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 lower end of the net being properly secured, the 
ends of the lashing are carried down to the sinker and made fast, in order to keep the 
net in place while going down. 
Four small brass rings are secured to the bag, at equal distances, a few inches 
below the upper edge of the silk-gauze lining, ami through them is rove a soft white 
tie line, which makes a complete round turn, the ends being passed through the same 
ring, then rove through small metal blocks on the lower bridle, and finally secured tm 
leads weighing 14 pounds each. Two tripping-lines with eyes in their upper extrem- 
ities are hooked over a friction clamp on the tow rope, then rove through small eyes; 
on the rim of the net, and through brass rings on the lower bridle above the metal 
blocks before mentioned. The ends being hitched to the leads support their weight, 
allowing the tie or draw string to hang loosely and the net to retain its natural form 
while sinking and being towed. 
