PRINCIPLES OF CONSTKUCTION. 91 



core to protect the latter, and also increase its diameter to take 

 a suflBcient number of sheathing wires. 



The types of cable manufacturing machinery illustrated in 

 Figs. 43 to 46 are those designed and made by the well- 

 known firm of Messrs. Johnson and Phillips, of London, to 

 whom the author is indebted for the use of the engravings. 

 The illustrations are also generally representative of machines 

 of this class. The serving machine (Fig. 43) consists of two yarn- 

 serving discs or heads (each carrying a set of spindles arranged in 

 two concentric rings for holding bobbins of yarn), one drawing- 

 ofF gear (seen in the front of the illustration), pulley for driving 

 the whole machine by belt, and pair of standards (seen at the 

 back) for supporting core drum spindle. The serving heads are 

 mounted on separate shafts, so that they can be driven in 

 opposite directions, and are hollow to allow the core to pass 

 through. 



Each shaft carries a driving pulley and runs in two bearings 

 (one on each side of the pulley) supported by A frames on one 

 side of the disc, leaving the other side with the bobbins free 

 from obstruction. The two heads are driven off the counter- 

 shaft by belt, one of the belts being crossed so that they are 

 driven in opposite directions. The core passes straight through 

 the hollow spindles and three times round the drum of the 

 draw-off gear, the jockey pulley riding on the last turn and 

 drawing out the served core from the machine. This gear Is 

 driven by spur and bevel wheels off the countershaft, and is 

 provided with change wheels for setting the speed according to 

 the lay required. As the discs revolve the yarn is wound off 

 each bobbin on to the core, two separate layers being formed in 

 ■opposite directions. The served core as it issues from this 

 machine is re-wound on drums and kept in water until the 

 moment it is required for jointing. The jute is sometimes 

 steeped in cutch (from the mangrove bark) or brine as a 

 preservative. 



We now come to the sheathing process, which is carried out 

 in a separate shop generally built parallel to the tank-house, so 

 that the finished cable as it leaves the various machines is 

 -delivered straight Into the tanks. 



The illustrations (Figs. 44 and 45) represent sheathing 

 machines for shore-end and deep-sea types respectively. The 



