i64 DISCOVERY REPORTS 



The drums carrying 500 fathoms of wire are 16 in. in extreme diameter and 5 in. 

 in clear width; those with 3500 fathoms of wire are 28 in. in diameter and 9I in. in 

 width. Tlie centre hub in all the drums is 6 in. in diameter. The drums are a little small 

 for the length of wire they are intended to carry; the full amount can only be accom- 

 modated when wound on under considerable strain, and to do this on board ship is a 

 task of some difficulty. The drums are of cast steel with the ends strengthened with 

 radiating ribs. They are clutched to the engine and are fitted with large band brakes, 

 operated by a foot lever which can be locked when desired by means of a screw clamp. 



Outboard Platforms, Samson Posts, Booms, etc. It has already been explained 

 that in view of the pronounced "tumble home" of the ship's side it was necessary 

 to work from outboard platforms, but this does not apply to the apparatus for deep 

 water bottles on the forecastle head. The wire from this machine is led through snatch- 

 blocks to the anchor davit, and the instruments are lowered into the water close to the 

 bow, where the sheer is ample. With the other two machines, platforms, fitted with 

 movable stanchions and chains, are hinged to the covering board, folding against the 

 bulwarks when not in use. 



When designing the equipment it was felt that the " tumble home " would also prove 

 a difficulty in another way, for it seemed probable that if the wire were not to foul the 

 ship's side during heavy rolling, it must be slung so far out that it would be beyond 

 the reach of the man on the platform. To obviate this difficulty a samson post, 4 in. 

 in diameter and 9 ft. 10 in. in length, is stepped in the rail and a boom of the same 

 diameter and io| ft. in length is hinged to the covering board opposite each of the 

 drums of the two after machines. The boom is fitted with a sheave at the end and its 

 topping lift passes through a fair-lead in the samson post to a small drum which can 

 be turned by hand and locked in any position by ratchet and pawl. With this method 

 the inclination of the boom, and consequently the distance of the wire from the ship's 

 side, can be regulated to suit the prevailing conditions: in heavy weather the boom 

 can be inclined well outboard and can be topped up to bring the wire within reach of 

 the operator when the apparatus is at the surface. The arrangement is indicated in 

 Fig. I. In actual practice it was found that there was less danger of apparatus being 

 damaged against the ship's side than was anticipated and that the use of booms and 

 topping lifts was scarcely necessary. With the shallow-water machine they were, how- 

 ever, retained, with the addition of a fair-lead consisting of a box of four small rollers, 

 to prevent the wire jumping out of the jib sheave. At the after machine a high davit 

 was substituted (Plate XI, fig. i) and this simpler arrangement, which permits the use 

 of a slung block for the jib fair-lead, is to be preferred. 



Light Accumulators. Light compression springs or accumulators, designed to take 



up sudden jars and minimise the effect of the rolling, are fitted to all the machines and 



in general design are somewhat similar to those used by Dr Schmidt in his oceano- 



graphical expeditions to the Mediterranean.^ The plan adopted for the two after 



1 Schmidt, Rep. Oceanogr. Exped. Mediterranean, 1908-10, I, p. 10, fig. 7, 1912. 



