140 SUBMARINE CABLE LAYING AND EEPAIEING. 



in bearings, and on the other spindle is a long screw placed 

 parallel to the edge of the cone. On the screw is a threaded 

 circular disc, the edge of which bears lightly against the sur- 

 face of the cone. If, say, the cone is stationary and the screw 

 revolved the disc will travel up the screw, as it is prevented 

 from turning by touching the cone; and if the screw is stationary 

 and the cone revolving the disc will travel down the screw, as 

 the friction of the cone causes the disc to turn with it. If the 

 spindles revolve in the same direction the screw has a left- 

 handed thread and vice versa. If the cone and screw are 

 both revolved the disc will travel up or down the screw in 

 accordance with the relative speeds of the two spindles. The 

 motion imparted to the disc by the revolving cone varies 

 according to the position of the disc ; if it is near the large 

 diameter of the cone the speed is greater, and if near the small 

 diameter it is less. When both cone and screw are in motion, 

 therefore, the disc soon finds for itself a position of rest on the 

 screw, such that the cone at this point tends to work it down 

 at the same rate as the screw tends to work it up. The position 

 of the disc is proportional to a certain ratio between the speeds 

 of the two spindles, and should the ratio of speeds change the 

 disc will take up another position and indicate the change. A 

 scale is placed behind the disc divided in degrees of excess speed 

 of the cable drum spindle over the wire drum spindle, and these 

 divisions are calibrated directly in percentages of slack, thus 

 giving a continuous indication. The brake weights can then 

 be adjusted for the required percentage slack, which can be kept 

 constant for any depth and waste of cable avoided. By means 

 of a train of clockwork and travelling paper-slip the nut is made 

 to imprint a continuous record of the percentage slack paid out. 

 The economy effected in cable payed-out amply covers the cost 

 of the steel wire. 



Particulars of the slack paid out and the lengths of each 

 type of cable laid are noted down in the paying-out log, together 

 with a chart of the course of the cable, so that every information 

 about the cable is ac hand when required for the carrying out 

 of repairs. The paying-out log is an abstract of each position, 

 or change of course, with calculated distances and lengths of 

 cable paid out, &c. The details recorded in this log are of a 

 series of positions, giving the latitude, longitude, and true course 



