R.S.S. 'WILLIAM SCORESBY': SCIENTIFIC EQUIPMENT 179 



The two Light Deck Machines are placed on the starboard side of the vessel, one 

 of them on the fore deck opposite the main-mast, and one further aft, abreast the engine 

 and boiler casing. Both these machines are equipped with the same type of engine, 

 made by Philip and Son of Dartmouth. The engine is of the compound enclosed type, 

 with cylinders 4 and 8 in. in diameter and a common stroke of 5 in., working at a 

 maximum of 600 revolutions a minute with a boiler pressure of 180 lb. to the square 

 inch. Each of these engines is coupled to a drum which carries 3500 fathoms of light 

 wire, 4 mm. in diameter. The drum is strongly constructed of cast steel; the centre 

 hub is 8 in. in diameter, the extreme diameter over flanges is about 29 in., and the 

 clear width between flanges is 10 in. With these dimensions the full amount of wire is 

 easily stowed. The connection between the engine shaft and the gearing for driving 

 the drum is by means of an ordinary dog clutch. The main spur wheel is bolted to the 

 side of the drum, and the pinion wheel, driven direct from the engine shaft, gears with 

 the spur wheel, giving a single purchase drive with a ratio of 5 to i. A band brake 

 operated by a foot lever is fitted, and is so arranged that the drum can be locked when 

 desired. A fork, fitted with rollers and operated by hand-driven screw gear was originally 

 provided for spreading wire on the drum. This fork proved unsatisfactory and it was 

 replaced by a small traveller carrying three rollers — two vertical and one horizontal. 



The after machine consists of the engine and drum described above and is used for 

 vertical plankton nets. The forward machine is for hydrological work, and the engine, 

 in addition to driving the drum of 4 mm. wire, is coupled on its forward side to a 

 sounding machine (Plate XVII, fig. 2). The three units composing this machine are 

 mounted on a common bedplate. The sounding machine is connected with the engine 

 by means of a dog clutch and is driven by machine-cut bronze gearing. 



During the first year of service it was found that in cold weather the drainage of the 

 engines was insufficient, resulting in damage to the cylinders. On renewal larger drains 

 and relief valves were fitted and the engines have since given no trouble. 



In the ' William Scoresby ' the operation of vertical nets and water bottles is more 

 easily eff'ected than in the 'Discovery'. Opposite each machine a davit is stepped in 

 the rail, the wire from the drum leading direct to a recording sheave slung at the davit 

 end. Accumulator springs of the type employed in the 'Discovery' were not fitted; 

 instead, the recording sheave is attached to a long pin which passes through a hole in 

 the end of the davit and is supported on the upper side by a compression spring. This 

 device is not very eff'ective, for the spring is too short to give sufiicient play to the wire. 



The Recording Sheaves for the plankton and hydrological machines are of the same 

 pattern as in the ' Discovery ' and showed the same defects (p. 167). A sheave of diff'erent 

 pattern is used with the centre drum of wire rope on the main winch ; it was supplied 

 by the Laboratoire Hydrographique at Copenhagen and is of the heavy type described 

 by Knudsen in 1923.^ This sheave is of the most solid construction and has proved 

 very satisfactory. 



1 Knudsen, Pub. Circ, Cons. Explor. Mer, 77, p. 14, 1923. 



