252 SUBMARINE CABLE LAYING AND REPAIRING. 



when the latter is built as a separate wheel, and keyed to the 

 shaft at a little distance from the drum. When so built the 

 strain comes on the spokes and keys of both drum and wheel 

 and a torsional strain is put on the shaft, which is avoided by 

 making the wheel one with the drum. As far back as 1863 

 Mr. F. C. Webb made this improvement in the gear he designed 

 for the cable-ship " Amberwitch," the repairing vessel for the 

 Persian Gulf cables. The brake on main brake-wheel B can be 

 set up by weighting the lever S. The hauling-ofF pulley H is 

 mounted on a separate shaft, with clutch and lever for throwing 

 in or out of gear. With the clutch over to one side the pulley 

 is set in motion at a circumferential speed a little in excess of 

 that of the drum, so pulling cable taut away from the latter, 

 as required during picking up. Putting the clutch over to the 

 other side disconnects the shaft from the driving pulley and 

 couples it to a small brake, E, the tension on which can be 

 adjusted by the lever to keep cable taut on its way to the 

 drum from the tank, as required in paying out. 



Driven off the drum shaft through the intermediary of the 

 toothed wheels T T, and worm on shaft W, is a simple form 

 of rotometer for recording the number of revolutions made. 

 The dial R, graduated in revolutions of the drum, is slowly 

 rotated by the action of the worm on its outer circumference, 

 the index hand remaining stationary, and being set to zero at 

 starting. This is read very easily, and there is nothing to get 

 out of order, while, like all rotometers which follow both the 

 forward and backward movements of the drum, it registers the 

 exact length of cable passing between bows and tank during 

 picking up or paying out without calculation. 



Two knives for fleeting the turns of cable on drum are 

 fitted on opposite sides of the drum, the forward one for 

 use in picking up, and the other behind for paying out. The 

 former is made movable, so that when it is required to remove 

 the turns of cable bodily off the drum this knife can be shifted 

 out of the way. This is frequently a necessary operation 

 where there is only one drum, as in this set of gear. 



For paying out, the pinion driving dram is thrown out of 

 gear and the drum used with the brake. When up to buoy 

 the drum is required for picking up buoyed end, so the turns 

 of cable are taken off it, first removing the forward knife. 



