SIR WILLIAM SIEMENS, F.R.S. 19 



cable, an accident in the machinery employed, or an unknown 

 chasm at the bottom, may at any moment cause the entire destruc- 

 tion of the cherished work. 



The machinery employed in paying 6ut cables consists of two 

 principal parts the guide apparatus and the brake apparatus. 

 The guide apparatus consists of a solid cone or cylinder in the 

 eye of the cable, and of a series of iron rings fastened above the 

 cable in crinoline fashion, this being the apparatus first introduced 

 by Newall and Co., and generally employed. The cable, on rising 

 from its coil, is confined in its motion between the cone and the 

 guide rings, and is thereby prevented from twisting round itself 

 and forming kinks. The cable passes through troughs and over 

 pulleys, which should always be well housed, from the hold along 

 the deck, over the brake wheel and a dynamometer wheel, over the 

 stern-pulley into the sea. 



A variety of opinions exists with regard to the apparatus which 

 ought to be employed for the paying out of cables, and the amount 

 of retaining force which should be applied, depending in its turn 

 upon the curve which the cable assumes in sinking to the bottom. 

 To my mind it appears perfectly clear that, supposing the vessel 

 to proceed at a uniform rate through the ocean, the line which the 

 cable assumes at any one time during its progress must be a straight 

 line. Suppose you have a cable of the specific gravity of 2, this 

 will descend say 40 feet per minute through the water, falling 

 laterally ; and if the ship moves forward 40 feet during that time, 

 the result will be that the cable will assume an inclined direction 

 from the ship to the bottom of the sea without any curvature, 

 forming an angle of 45 with the horizon. 



(TJie Chairman : To a certain distance, till the terminal velocity 

 is arrived at, there will be a curvature.) 



I suppose that the cable assumes its maximum velocity from the 

 moment it touches .the water, its acceleration having been accom- 

 plished in descending through the air to the water level ; in fact, 

 the time for accelerating the speed must be proportionately exceed- 

 ingly small, considering that a cable may be an hour and a half, or 

 two or three hours, before it reaches the bottom, and that the 

 maximum velocity which the resistance in the water permits it to 

 acquire would be attained by a free fall through 5 feet of space. 



The cable is acted upon by two forces, one force tending to 



c 2 



