R.R.S. 'DISCOVERY': SCIENTIFIC EQUIPMENT 163 



Auxiliary Winch-drum. Close to the winch on the starboard side is a drum fitted with 

 ckitch, brake and hand-operated traversing gear, designed to accommodate 3000 fathoms 

 of wire 6 mm. in diameter (Plate X, fig. 2). It is driven by a sprocket wheel on the 

 main shaft of the winch by means of a roller chain, the brake handle being extended 

 to the control position in the winch house. When not in use the chain was discon- 

 nected. This auxiliary winch was intended for handling grabs and light bottom 

 apparatus, but was used mainly for the storage of lengths of wire used with fish traps. 



Light Deck Machines. For hydrological work and vertical plankton nets three 

 small engines and drums are provided in addition to the sounding machine. All are 

 placed on the port side and are used with wire 4 mm. in diameter. One engine, coupled 

 to a drum holding 3500 fathoms of wire, is placed near the winch house (Plate XI, 

 figs. I, 2) and is used for vertical nets. The second, just forward of the bridge (PlateXII, 

 figs. I, 2), has two drums, one on either side, each with 500 fathoms of wire, and is 

 used mainly for insulating water bottles worked at shallow depths. The third engine 

 (Plate XIII, fig. i), with 3500 fathoms of wire, is placed on the forecastle head and with 

 it deep-water temperatures and salinities are taken with reversing water bottles. All 

 three machines are fitted with the same type of engine, made by E. Reader and Sons 

 — a twin cylinder two-crank engine, class D.F., with cylinders 3! in. in diameter by 

 3 in. stroke, designed to develop 9 brake horse-power at 500 revolutions per minute 

 with 155 lb. steam pressure at the stop valve. Originally these engines were directly 

 coupled to pinion shafts, driving spur wheels bolted to the rims of the drums, the ratio 

 of gearing being 1-87 to i in the machine carrying 500 fathom drums and 3-47 to i in 

 those with 3500 fathom drums. The machine with the shorter length of wire was quite 

 satisfactory with this ratio, but the two deep-water machines, though they doubtless 

 possessed sufficient power, proved unable to start with a standing weight of 2| cwt.^ 

 Even wheii the engine did start, with a lesser weight, it hauled very slowly and was 

 liable to stop every time the vessel rolled to starboard. To overcome this difficulty 

 further gearing was introduced by means of a lay shaft driven by sprocket wheels and 

 a roller chain, the new gearing ratio being 6-3 to i. This alteration was made to both 

 deep-water machines and brought immediate improvement. The machines have since 

 given complete satisfaction and we believe they could not be surpassed for oceano- 

 graphical work. They start easily under any conditions, can on an average haul 1000 m 

 of wire in 5Jmin.'- and can be throttled down to the slowest possible movement, 

 so that an instrument attached to the wire can be brought without the least trouble 

 to the exact height required. It may be noted that these machines, with 6-3 to i gearing 

 ratio and with the drum full of wire, can just lift a dead weight of 5^ cwt. 



1 That is to say, with 3000 m. of wire, 3 reversing water bottles and a 28-lb. lead. 



- With a series of Ekman reversing water bottles the rates of hauling were approximately: 



From 4000 to 3000 m. ... 7 min. 



„ 3000 „ 2000 „ ... 6 „ 



„ 2000 ,, 1000 ,, ... 5 „ 



,, 1000 ,, surface ... 4 ,, 



