INTRODUCTION 



LS Experimental improvised line, 235 fathoms long, with end made fast to ship. Outboard end carried 



a 50 lb. weight and was rigged with 16 traces and hooks. 

 N 50 50 cm. silk tow-net. Mouth circular, 50 cm. (19-5 in.) diameter: 200 meshes to the linear inch. 



N 70 70 cm. tow-net. Mouth circular, 70 cm. (27-5 in.) diameter: mesh graded, at cod-end of silk, with 74 



meshes to the linear inch. 

 N 100 1 m. tow-net. Mouth circular, 1 m. (3-3 ft.) diameter: stramin, with 10-12 meshes to the linear inch. 1 



NH Hand net. 



OTC Commercial otter trawl. Head rope 74 ft. (22-6 m.) long; mesh at cod-end 1 h in. (3-8 cm.). 



Sh. Coll. Shore collecting. 

 SSL Lumby surface sampler, for collecting surface water samples while under weigh. Modified version, as 



described by J. R. Lumby 1928. 2 

 TNL Large fish trap, 12x6x6 ft. : a rigid metal frame covered with wire netting of 1 in. mesh, and having 



two funnel-shaped entrances. 

 TYF Young fish trawl. A bag of stramin, 10-12 meshes to the linear inch, attached to a circular frame 2 m. 



(6-6 ft.) in diameter, with a bucket at the cod-end. 

 V Vertical. 



The addition of the symbols B, H or V to those used for the tow-nets indicates whether they were 

 hauled obliquely, horizontally or vertically. Where the depth interval indicates that a net fished 

 vertically was closed, this was effected on the Nansen principle. The maximum depths reached by 

 horizontal and oblique nets were determined by the use of Kelvin sounding tubes, and this is recorded 

 by insertion of the symbol KT in the ' Remarks ' column. Wire angles, expressed as deviations from 

 the vertical and determined by a simple inclinometer, are given for water samples collected with the 

 Nansen-Pettersson water-bottle, but no correction to the depth has been applied. Depths of reversing 

 water-bottles have been calculated from the thermometric depths, using the method of Pollack. 3 The 

 small index figure placed against the figure for depth shows from which hoist of water bottles the 

 sample was obtained. 



The Bathythermograph conformed to the standard of accuracy laid down by the makers ; it was 

 calibrated frequently during the commission, showing negligible variance from the original cali- 

 bration. The depth limit of this instrument is 450 ft. (138 m.). It was our practice to work it with the 

 ship hove to, since we worked a vertical net at all our BT stations, and therefore no time was lost by 

 departing from the normal U.S. Navy method of using the instrument with the ship under way. 

 This explains why we were so frequently able to work the instrument down to the lower limit of its 

 range. 



1 Earlier versions of the N 100 were of graded mesh, but also had stramin at the cod-end. 



2 Journ. du Conseil, ill, No. 3, pp. 340-50. 



3 Pollack, M. J., 1950. Notes on determining the depth of sampling in serial oceanographic observations. Journ. Mar. 

 Research, ix, No. 1. 



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