12 " THETIS " SCIENTIFIC RESULTS. 



that, in place of the usual single warp, two were used, and the 

 advantage of this was on one occasion clearly demonstrated. At 

 Station 13 the forward warp broke, notwithstanding the fact that 

 it was composed of the best wire-rope, an inch in diameter. 

 Had the net not been held by a second warp, we should have lost 

 ■everything — an experience not new to me. This double warp 

 does away with the necessity of a bridle, and, had we been 

 able to pay it out over the stern instead of the port side, its 

 advantages would have been still further increased. In working 

 an otter trawl at varying depths some nice adjustment is neces- 

 sary to ensure the boards always running at the correct angle. 

 In shallow water the warp paid out was about three times the 

 indicated depth, but in deeper water the proportion was lessened 

 in consequence of the greater weight of the warp. If hemp, 

 instead of wire, had been used, much more rope would have been 

 required. 



The net being intended for economic and experimental 

 purposes, the mesh was altogether too large to meet the require- 

 ments of a naturalist ; near the mouth it was about five inches, 

 and in consequence large quantities of fish escaped. Indeed, the 

 first indication of a successful haul, from an economic standpoint, 

 was the large number of Gurnards (Triglidce) rising to the surface, 

 belly upwards, and floating away astern. At the smaller end, 

 the mesh was also large, consequently the smaller organisms 

 among which a zoologist would expect to reap the richest harvest, 

 were, for the most part, not obtained. When mud was freely 

 encountered, our efforts were more successful, and it was on such 

 occasions only that I was able to gather the more minute 

 Invertebrate life. In such cases as much mud as possible 

 was put through the filters of various gauges and a fair 

 unwashed sample retained to be afterwards worked for microscopic 

 forms. On several occasions when mud had without doubt been 

 netted, all but a trace of it had been sifted out as the trawl 

 passed through the water. With a view of retaining some of this 

 mud, a canvas bag was attached to an iron hoop within the 

 bunt end of the net and thus on several occasions the object was 

 effected. As considerable trouble was entailed in securing and 

 removin.g the bag, I did not care to try the good nature of our 

 trawlers too frequently. 



DREDGE. 



I had hoped to largely supplement our takings by means of 

 ■dredges specially designed for arresting the smaller organisms 

 which the trawl was not calculated to retain. In this I was much 

 disappointed. Having no appliances for running out a separate 

 warp, the dredge had to be attached to the bunt or "cod-line" of 



