140 THE SCIENTIFIC PAPERS OF 



ship's speed can be at all times noted on the index of a Berthon 

 hydrostatic log. 



The deck is fitted with machinery to be used in laying opera- 

 tions, which will be best described by tracing the path of the cable 

 from the tanks to the sea. Let us begin with the bow compart- 

 ment : the cable, which lies coiled round one of Newall's cones, 

 begins to be unwound, passes up through an eye carried on a beam 

 placed across the hatch, next over a large pulley fitted with guides, 

 and by a second pulley is gently made to follow a straight wooden 

 trough fitted with friction rollers, which carries it aft to near the 

 funnels ; here it passes through the " jockey," a device for 

 regulating the strain, consisting of a wheel riding on the cable, 

 which can be adjusted by a lever, and a drum fitted with a brake. 

 Thence it passes on to a " compound paying-out and picking-Dp 

 machine," which consists of a large drum provided with a friction 

 brake, and round it the cable passes three times ; it is also furnished 

 with a steam-engine, which by means of a clutch can be geared on 

 to the drum when required. Now, in paying out, the cable causes 

 the drum to revolve as it runs over it, and the brakes regulate 

 the speed as the vessel moves onward ; but should a fault or other 

 accident render it necessary to recover a portion, the drum is 

 stopped and geared on to the engine, the ship's engines are re- 

 versed, the stern rudder fixed ; and so what was formerly the bow 

 is now the stern, while the little engine hauls in the cable over 

 the same drum which before was used to pay it out ; thus it is 

 coiled back into the same tank whence it started. By this means 

 the necessity of passing the cable astern before proceeding to haul 

 it in is avoided. It was during this operation that an accident 

 befell the Atlantic cable in 1865, causing its loss for a time. 



The next apparatus is a dynamometer, consisting of three 

 pulleys, one fixed, and the centre one, which rests on the cable, 

 movable in a vertical plane ; by this strain is registered and ad- 

 justed. After passing this the cable runs into the sea over a pulley 

 carried on girders and constructed so as to swing freely on an axis 

 parallel to the length of the ship, so that, should the vessel make 

 lee-way, the pulley will follow the direction of the cable, and thus 

 friction and sharp bends are avoided. The bows are also fitted 

 with a similar pulley, compound machine, and dynamometer. We 

 see that by these devices the cable is kept perfectly under control, 



