THE SOUNDING APPARATUS 319 



line, where a small weight (a) hangs; then it is lowered 

 until the indicator-wheel, over which the line passes, 

 shows 100 metres (54 fathoms) ; Apparatus II. is then 

 put on, and it is lowered again for another 100 metres, 

 when Apparatus I. is put on and the line paid out for 

 300 metres (164 fathoms) — that is, until the indicator- 

 wheel shows 500 metres (273 fathoms). The upper 

 Apparatus (I.) is then at 300 metres (164 fathoms). 

 No. II. at 400 metres (218 fathoms), and No. III. at 

 500 metres (273 fathoms) . Under Apparatus I. and II. 

 is hung a slipping sinker (about 8 centimetres, or 

 31 inches, long, and 3 centimetres, or li inches, in 

 diameter). To the water-samplers are attached ther- 

 mometers ( 6 ) in tubes arranged for the purpose. 



The water-samplers themselves consist of a brass 

 cylinder (c), about 38 centimetres (15 inches) long and 

 4 centimetres (1^ inches) in diameter (about half a litre 

 of water), set in a frame (d). At about the middle of 

 the cylinder are pivots, which rest in bearings on the 

 frame, so that the cylinder can be swung 180 degrees 

 (straight up and down). 



The cylinder, while being lowered in an inverted 

 position, is open at both ends, so that the water can 

 pass through. But at its upper and lower ends are 

 valves, working on hinges and provided with packing. 

 When the apparatus is released, the cylinder swings 

 round, and these valves then automatically close the 

 ends of the cylinder. The water that is thus caught in 



