The insulated core was first surrounded with a serving of hemp saturated with a mixture of tar, pitch, linseed-oil, and wax; and then sheathed spirally with an armor of eighteen strands, each containing seven iron wires of No. 22 B.W.G., the completed strand being No. 14 gage in diameter. [Illustration: FIG. 5.--Manufacture of the Core.] The cable (Fig. 8) was then finally drawn through another mixture of tar. Its weight in air was 1 ton per N.M., and in water only 13.4 hundredweight, bearing a strain of 3 tons 5 hundredweight before breaking--equivalent to nearly five miles of its weight in water. For each end approaching the shore, the sheathing (see Fig. 9) consisted of twelve wires of No. 0 gauge, making a total weight of about nine tons to the mile. This type was adopted for the first ten miles from the Irish coast, and for fifteen miles from the landing at Newfoundland, at both of which localities rocks had been found to abound plentifully--so much so that the armor was insufficient, and present practise provides double the weight under similar conditions. [Illustration: FIG. 6.--Serving the Core with Hemp-Yarn.] [Illustration: FIG. 7.--Applying the Iron Sheathing.] [Illustration: FIG. 8.--The Deep Sea Cable.] [Illustration: FIG. 9.--The Shore-End Cable.] Only four months was allowed for the manufacture of this 2,500 miles of cable, which had to be delivered in June of that year (1857). This involved the preparation and drawing of 20,500 miles of copper wire (providing for the lay) and stranding into the 2,500 miles of conductor. For the insulation nearly 300 tons of gutta-percha required to be prepared, and the three separate layers of gutta-percha required to be applied to the wire, subsequently followed by the spiral serving of yarn. Finally--and with a due allowance for lay--367,500 miles of wire had to be drawn, from 1,687 tons of charcoal iron, and laid up into 50,000 miles of strand for the outer sheathing. The entire length of copper and iron wire employed was, therefore, 340,500 miles--enough to engirdle the earth thirteen times, and considerably more than enough to extend from the earth to the moon. The work was enormously increased, of course, on account of the sheathing being composed of a number of strands instead of several single wires. While having certain mechanical advantages at the outset, this stranded sheathing is not a durable type of cable--besides being somewhat costly--and is never adopted nowadays. The contract price for the entire cable was £225,000, the core costing £40 and the armor £50 per mile.[18] As fast as the cable was made at the respective factories, it was coiled into iron tanks ready for shipment. [Illustration: FIG. 10.--Coiling the Finished Cable into the Factory Tanks.]