70 THE SCIENTIFIC PAPERS OF 



shown in Fig. 6, Plate 4, so placed that the wire to be coated 

 passes in a straight line through them all, receiving in each 

 successive machine an additional coating, with the longitudinal 

 seams at right angles to those of the previous and succeeding 

 coatings, as seen in Fig. 11, Plate 5, which is effected by the 

 different angular positions in which the machines are placed. 

 The last machine in the train is supplied with strips of cloth or 

 felt covered with india-rubber, which is also capable of being 

 joined by compression of the fresh-cut edges, and is extremely 

 useful in adding firmness and protection to the insulated con- 

 ductor. 



This machine is also applicable, with certain modifications of 

 details, for covering wire with the compound of india-rubber, 

 shellac, and pounded flint, known by the name of Wray's mixture, 

 which possesses in common with india-rubber very remarkable 

 insulating properties. The machine is also applicable, with great 

 apparent advantage, for the manufacture of india-rubber tubes, 

 and for several other similar purposes. In producing tubes by 

 this process, a spiral or tube of wires is first prepared, which is 

 coated with india-rubber in one or several layers, with or without 

 intermediate layers of canvas previously coated with india-rubber. 

 The spiral wire is then either withdrawn or left to support the 

 tube, which is finally subjected to the vulcanising process. 



In order to produce a submarine cable, an outer covering is 

 required for protection and strength. Instead of the ordinary 

 hemp serving and iron sheathing, the author proposes to saturate 

 hemp yarn with a cement consisting of ordinary marine glue 

 mixed with a certain proportion of pitch and shellac, applied to 

 the yarn in a fluid state and under pressure so as to penetrate the 

 fibre completely. Two or more layers of this yarn are put upon 

 the insulated conductor by means of a train of machines, which 

 cause each strand to be drawn tight uniformly, and to pass 

 separately through a heated chamber, so as to soften the cement 

 and unite the yarn in complete layers upon the core, winding 

 alternately right and left. The covering thus produced combines 

 great tensile strength and lightness with the power to exclude the 

 bea water from the core. It thus adds very considerably to the 

 insulating coating, whereby the retarding effect of induction is 

 greatly diminished ; and forms a thorough protection to the more 



