R.R.S. 'DISCOVERY': SCIENTIFIC EQUIPMENT 169 



wire to part. The fork for guiding the wire on to the drum did not prove satisfactory, 

 and was replaced by a guide formed of three small rollers (two vertical and one horizontal) 

 fitted to a transverse bar and moved by a lever. 



The wire used is single-strand piano wire, 0-028 in. in diameter and with a breaking 

 strain of 220 lb. Experiments were also made with a fine 7-strand wire 0-039 i"- ^^ 

 diameter with a breaking strain of 250 lb. : it was found that the 7-strand wire was very 

 perishable and its use was discontinued. 



A Kelvin sounding machine, driven by electric motor, was fitted on the poop deck. 

 This machine can be employed in the ordinary way for determining the depth when 

 the vessel is stationary, and with the use of the well-known Kelvin tubes, reliable 

 soundings can also be taken while the vessel is under way. As an aid in navigation it is 

 a most valuable instrument and it was frequently used for taking soundings in the course 

 of scientific work. The machine is provided with a dial which indicates the amount 

 of wire run out, and the wire itself is ,'^ in. in diameter, composed of seven strands 

 of 24 S.W.G., and has a breaking strain of 280 lb. 



The internal accommodation for scientific work on board the ' Discovery' comprises 

 two laboratories, a darkroom, two holds, and a locker in the topgallant forecastle. 



The Biological Laboratory, as already mentioned, is placed on the upper deck, 

 at the after end of a deck house which also contains the chart room, a spare cabin and 

 the wireless operator's room. It has a door on either side to the deck, and one leading 

 into a vestibule at the head of the companion to the wardroom. The general arrange- 

 ments are sufficiently well shown in the sketch (Fig. 2) and plan (Fig. 3), but one or 

 two points perhaps deserve special mention. 



The portholes are 14 in. in diameter and are placed much lower than usual, 3I in. 

 above bench level, in order to give the best possible light for microscopic work; and, 

 in view of the large amount of bench space that would have been taken up by their 

 dead lights and screw clamps, those on the after bulkhead are reversed and are opened 

 and closed from the outside. The benches give seating accommodation for four and 

 are so placed that those using the centre table face thwartships, a position which is 

 preferable for work in a rolling vessel. The chairs of the two side benches have folding 

 backs ; they run on brass rails flush with the deck and can be pushed under the bench 

 when not in use. All microscope stands are drilled and can be bolted to a brass plate 

 countersunk in the bench surface. 



The swing table, 20 in. by 33 in., is built of teak, with iron stays carrying a tray 

 below the table and a lead weight of 56 lb. This table was a very essential part of the 

 equipment: except in the calmest weather it was in constant use. It would have 

 been improved with more space round it. Two small swing tables, bracketed to the 

 after bulkhead between portholes, were useful for small dishes of specimens. 



The sink is supplied with fresh and salt water from two small tanks placed on the 

 bridge, and above it, in an alcove built out over the companion, are three 20 litre glass 



