NATURAL PHILOSOPHY. 129 



The first deep-sea length, of about nine hundred and fifty miles, for from 

 five to eight hundred fathoms, is covered, like the Atlantic cable, with 

 eighteen No. 11 gauge solid iron wires, weighing two tons the mile in air, 

 thirty-three hundredweight in water, and equal to a strain of nearly eight 

 tons. The deepest sea part is enclosed in twelve steel wires of No. 14 gauge, 

 each wire being spun round and enclosed in a separate strand of hemp, in 

 order, if possible, to take off that dangerous springiness and tendency to 

 kink which makes all steel-wire rope, even when coiled, so lively, and so 

 much resembling a cargo of live eels. The cable, the chief points of which 

 we have thus described, is necessarily a most expensive one; for, as we have 

 already stated, the government have contracted that all parts of the material 

 and workmanship should be of the finest possible kind. 



Nevertheless, in spite of all the care that has been taken to secure a good 

 rope, and the improvement which, with regard to strength with a certain 

 amount of lightness, the deep-sea portion of this cable undoubtedly displays, 

 it is still, we are sorry to say, constructed on the old self-destructive principle 

 of spiral iron wires round a soft core, one of the most faulty mechanical 

 arrangements that could have been attempted. There is not a single engi- 

 neer of eminence who does not condemn the principle of laying on the out- 

 side wires spirally, instead of longitudinally, in a line with the strain they 

 have to resist. Why the old arrangement is persisted in at the present day 

 it is difficult to imagine, unless it is due to the fact that most of the wire- 

 rope manufacturers have their machines constructed for laying on the wires 

 spirally, and do not care to make others which will render the completion 

 of their work slower, more difficult, and less profitable. Four years ago, 

 when the plan of construction of the Atlantic cable was resolved on, we most 

 strongly deprecated this arrangement-, and the event has so clearly justified 

 what we then pointed out would be the consequences, that we may be excused 

 for quoting the opinion on the present occasion: 



" Whenever a cable is constructed with spiral wires round a soft core, any 

 severe strain in paying it out must, by stretching the outside wires, either 

 attenuate or break the insulation of the copper conductor. This is a simple 

 fact, which those least conversant with mechanics can easily understand. 

 We do not mean to say that the Atlantic cable cannot succeed, but the 

 chances are very much against it; and it is certain that before it has been 

 down twelve months it will, like most others similarly constructed, be per- 

 fectly useless. If it does answer even temporarily, it will not be due to the 

 plan on which it is made, but in spite of it." 



We shall, on another occasion, inform our readers of the chief principles 

 on. which the light cable before mentioned is being constructed, and the 

 prospects which cables of that description hold out of being successful when 

 laid. All that we have at present to add with regard to the Gibraltar cable is, 

 that the contractors undertake to submerge it at their own risk and expense; 

 and to insure proper fulfilment of this portion of their task, the government 

 very wisely retain five per cent of the price of the whole cable (which is 

 nearly 300,000) in their own hands, and further compel Messrs. Glass and 

 Elliot to give security to the amount of 20,000 that the rope shall be suc- 

 cessfully laid. It is proposed to submerge it in two equal portions one 

 from Gibraltar to Cape Finisterre, and one from Finisterre to (we hope) the 

 southwest coast of Ireland. It is anticipated that the whole rope will be laid 

 early in 1801. London Times. 



