WILLIAM SIEMENS, F.R.S. 23 



only effective method of laying the cable to the bottom of a chasm 

 would be to stop the vessel over it until the cable assumes a verti- 

 cal position, aud then to proceed slowly onward. 



It is desirable that a deep-sea cable should be very flexible, so 

 as to accommodate itself thoroughly to the irregularities of the 

 ground, and in this respect the copper or zinc-sheathed cable 

 leaves little to be desired. 



Time does not permit me to enter upon the consideration of 

 untried modes of constructing and submerging cables. The elec- 

 trical tests applied during the operation of paying-out, and for 

 determining the position of faults in existing cables, is a most 

 interesting branch of the science of telegraphic engineering, which 

 I shall also have to pass over on this occasion, referring those 

 interested to the Government Blue Book of 1861, and other 

 sources of information. Nor does time permit me to describe the 

 particular arrangements of instruments for working long sub- 

 marine lines. Enough I hope has been said to justify the following 

 conclusions : 



1. That the insulating materials now used in the construction 

 of deep-sea cables, are efficient and likely to endure until the 

 protecting sheathing gives way. 



2. That for shores and shallow seas, heavy iron-clad cables of 

 from 5 to 10 tons weight per mile have proved practically success- 

 ful, but that a further protection of the iron wires is desirable to 

 increase their durability. 



3. That for deep seas, durability cannot be obtained by weight 

 of iron sheathing, but that a sheathing of moderate weight, which 

 is capable of resisting both the chemical action, of sea water and 

 the teeth of marine animals, is requisite. 



4. That a hemp covered cable, or a bare insulated conductor, 

 without a metallic sheathing of some sort, is highly objectionable. 



5. That the present mode of paying out is safe and efficient 

 under proper management, although capable of further improve- 

 ment. 



