. Discovery reports. Discovery (Ship); Scientific expeditions. PLANKTON NETS AND APPARATUS i8i APPARATUS AND METHODS PLANKTON NETS AND APPARATUS Six different types of plankton net were used in the investigations: a small silk net on a ring of 50 cm. diameter, a series of four nets of graded mesh, with diameters of 70, 100, 200 and 450 cm. respectively, and the Petersen young-fish trawl, which was used at first with the otter boards as a trawl proper and later as a tow-net on a 200 cm. ring. These nets will be referred to as the N 50, N 70, N 100, N 200, N 450 and TYF respectively. The N 50 wa
. Discovery reports. Discovery (Ship); Scientific expeditions. PLANKTON NETS AND APPARATUS i8i APPARATUS AND METHODS PLANKTON NETS AND APPARATUS Six different types of plankton net were used in the investigations: a small silk net on a ring of 50 cm. diameter, a series of four nets of graded mesh, with diameters of 70, 100, 200 and 450 cm. respectively, and the Petersen young-fish trawl, which was used at first with the otter boards as a trawl proper and later as a tow-net on a 200 cm. ring. These nets will be referred to as the N 50, N 70, N 100, N 200, N 450 and TYF respectively. The N 50 was almost exclusively used for vertical hauls, the N 70 vertically, hori- zontally or obliquely, the N 100 horizontally, obliquely, or very occasionally vertically, and the remainder horizontally only. All the nets could be closed, if necessary, by messengers and closing mechanisms on the Nansen principle. Whilst differing in size of mesh and details of construction, according to their different functions, all the nets, with the exception of the TYF, follow the same general plan shown in Fig. 6. Between the ring R and the conical catching part of the net BC there. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Institute of Oceanographic Sciences (Great Britain); National Institute of Oceanography; Great Britain. Colonial Office. "Discovery" Committee. London, New York, Cambridge University Press
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