67A' WILLIAM SIEMENS, F.R.S. 89 



miles per hour ; then, if the ship was going at six miles an 

 hour, the inclination at which the cable would remain would prac- 

 t it-ally be 1 to 3, or if it went at four miles an hour 1 to 2, or if at 

 hv<> miles an hour 1 to 1 ; so that, unless the velocity of the ship 

 c-hiiD^vd. tin- cable must descend nearly in a straight line. Then 

 OUne the question why it was found impossible in practice to do 

 without a certain retarding force during the operation of laying. 

 While the cable was, as it were, sliding down the inclined plane, 

 the force exerted was so great that, if it were not resisted, it would 

 t-au-c the cable to run out with such velocity as to produce an 

 immense waste of cable. When it got to the depth of 1,000 

 fathoms the force with which the cable ran out was very great 

 indeed, and it required to be resisted, otherwise twice or thrice as 

 much cable as was required would be paid out. He thought it 

 was of comparatively little importance what method of paying out 

 was adopted so long as it was a safe one, affording the means of 

 varying the retarding force at will. It appeared to him that the 

 great point was to make the apparatus as simple as possible, so 

 that no kinks or other disturbances could arise. With regard to 

 the measure of the retarding force, that would depend entirely 

 upon the specific gravity of the cable and the depth. The laying 

 of a heavy iron-coated cable in 2,000 fathoms water was a difficult 

 and critical operation. One of very small specific gravity might 

 perhaps go out nearly in the upward curve described by Capt. 

 Selwyn ; and if it did so, although there was no retarding power 

 acting upon it, there would be danger that sufficient slack would 

 not be produced at the bottom. Then came the considerations as 

 to the nature of the bottom. If the cable were laid along a great 

 plateau, then moderate slack was sufficient, but with a precipitous 

 bottom, it was difficult to lay out sufficient slack for the safety of 

 the cable. He would mention a case which came within his own 

 knowledge. A cable had to be laid not far from the Spanish 

 coast, and, according to the soundings previously taken, the bottom 

 descended in a slope of about one in four, but it turned out that in 

 reality the shore was very mountainous, and of volcanic nature. 

 At about eleven knots out at sea, there was a deep valley with 

 precipitous sides. The depth of one edge of this valley was about 

 700 fathoms ; of the valley itself 1,000 fathoms, and of the other 

 edge 900 fathoms, so that the cable was suspended between the 



