GALVANIZED STEEL-WIRE STRAND. For Smokestack Guys, Signal Strand, etc. This strand is composed of 7 wires, twisted together into a single strand. 100 Feet. For special purposes these strands can be made of 50 to 100 per cent greater tensile strength. When used to run over sheaves or pulleys the use of soft-iron stock is advisable. FLEXIBLE STEEL-WIRE CABLES FOR VESSELS. (Trenton Iron Co., 1886.) With numerous disadvantages, the system of working ships' anchors with chain cables is still in vogue. A heavy chain cable contributes to the holding-power of the anchor, and the facility of increasing that resistance by paying out the cable is prized as an advantage. The requisite holdingpower is obtained, however, by the combined action of a comparatively light anchor and a correspondingly great mass of chain of little service in proportion to its weight or to the weight of the anchor. If the weight and size of the anchor were increased so as to give the greatest holding-power required, and it were attached by means of a light wire cable, the combined weight of the cable and anchor would be much less than the total weight of the chain and anchor, and the facility of handling would be much greater. English shipbuilders have taken the initiative in this direction, and many of the largest and most serviceable vessels afloat are fitted with steel-wire cables. They have given complete satisfaction. The Trenton Iron Co.'s cables are made of crucible cast-steel wire, and guaranteed to fulfil Lloyd's requirements. They are composed of 72 wires subdivided into six strands of twelve wires each. In order to obtain great flexibility, hempen centres are introduced in the strands as well as in the completed cable. FLEXIBLE STEEL-WIRE HAWSERS. These hawsers are extensively used, They are made with six strands of twelve wires each, hemp centres being inserted in the individual strands as well as in the completed rope. The material employed is crucible cast steel, galvanized, and guaranteed to fulfil Lloyd's requirements. They are only one third the weight of hempen hawsers; and are sufficiently pliable to work round any bitts to which hempen rope of equivalent strength can be applied. 13-inch tarred Russian hemp hawser weighs about 39 lbs. per fathom. 10-inch white manila hawser weighs about 20 lbs. per fathom. 1-inch stud chain weighs about 68 lbs. per fathom. 4-inch galvanized steel hawser weighs about 12 lbs. per fathom. Each of the above named has about the same tensile strength. SPECIFICATIONS FOR GALVANIZED IRON WI Issued by the British Postal Telegraph Authoriti Weight per Mile. of the Standard Size at 60° Fahr Resistance per Mile STRENGTH OF PIANO-WIRE. The average strength of English piano-wire is given as follows by W ster, Horsfals & Lean: Numbers Equivalents Ultimat in Music-in Fractions Tensil wire of inches in Strength Gauge. Pounds These strengths range from 300,000 to 340,000 lbs. per sq. in. The comp sition of this wire is as follows: Carbon, 0.570; silicon, 0.090; sulphur, 00 phosphorus, 0.018; manganese, 0.425. "PLOUGH"-STEEL WIRE. The term "plough," given in England to steel wire of high quality, w derived from the fact that such wire is used for the construction of rop used for ploughing purposes. It is to be hoped that the term will not used in this country, as it tends to confusion of terms. Plough-steel known here in some steel-works as the quality of plate steel used for th mould-boards of ploughs, for which a very ordinary grade is good enough Experiments by Dr. Percy on the English plough-steel (so-called) gave th following results: Specific gravity, 7.814; carbon, 0.828 per cent; manga nese, 0.587 per cent; silicon, 0.143 per cent; sulphur, 0.009 per cent; pho phorus, nil; copper, 0.030 per cent. No traces of chromium, titanium, d tungsten were found. The breaking strains of the wire were as follows: Diameter, inch. Pounds per sq. inch........ 344,960 257,600 The elongation was only from 0.75 to 1.1 per cent. WIRES OF DIFFERENT METALS AND ALLOYS. (J. Bucknall Smith's Treatise on Wire.) Brass Wire is commonly composed of an alloy of 1 3/4 to 2 parts of copper to 1 part of zinc. The tensile strength ranges from 20 to 40 tons per square inch, increasing with the percentage of zinc in the alloy. German or Nickel Silver, an alloy of copper, zinc, and nickel, is practically brass whitened by the addition of nickel. It has been drawn into wire as fine as .002" diam. Platinum wire may be drawn into the finest sizes. On account of its high price its use is practically confined to special scientific instruments and electrical appliances in which resistances to high temperature, oxygen, and acids are essential. It expands less than other metals when heated, which property permits its being sealed in glass without fear of cracking. It is therefore used in incandescent electric lamps. Phosphor-bronze Wire contains from 2 to 6 per cent of tin and from 1/20 to 1/8 per cent of phosphorus. The presence of phosphorus is detrimental to electric conductivity. "Delta-metal " wire is made from an alloy of copper, iron, and zinc. Its strength ranges from 45 to 62 tons per square inch. It is used for some kinds of wire rope, also for wire gauze. It is not subject to deposits of verdigris. It has great toughness, even when its tensile strength is over 60 tons per square inch. Aluminum Wire. Specific gravity .268. Tensile strength only about 10 tons per square inch. It has been drawn as fine as 11,400 yards to the unce, or .042 grains per yard. Aluminum Bronze, 50 copper, 10 aluminum, has high strength and ductility; is inoxidizable, sonorous. Its electric conductivity is 12.6 per cent. Silicon Bronze, patented in 1882 by L. Weiler of Paris, is made as follows: Fluosilicate of potash, pounded glass, chloride of sodium and calcium, carbonate of soda and lime, are heated in a plumbago crucible, and after the reaction takes place the contents are thrown into the molten bronze to be treated. Silicon-bronze wire has a conductivity of from 40 to 98 per cent of that of copper wire and four times more than that of iron, while its tensile strength is nearly that of steel, or 28 to 55 tons per square inch of section. The conductivity decreases as the tensile strength increases. Wire whose conductivity equals 95 per cent of that of pure copper gives a tensile strength of 28 tons per square inch, but when its conductivity is 34 per cent of pure copper, its strength is 50 tons per square inch. It is being largely used for telegraph wires. It has great resistance to oxidation. Ordinary Drawn and Annealed Copper Wire has a strength of from 15 to 20 tons per square inch. SPECIFICATIONS FOR HARD-DRAWN COPPER WIRE. The British Post Office authorities require that hard-drawn copper wire supplied to them shall be of the lengths, sizes, weights, strengths, and conductivities as set forth in the annexed table. According to English practice, cable-traction ropes, of about 31⁄2 in circumference, are commonly constructed with six strands of seven or teen wires, the lays in the strands varying from, say. 3 in. to 3% in., and lays in the ropes from, say, 71⁄2 in. to 9 in. In the United States, howe strands of nineteen wires are generally preferred, as being more flexil but, on the other hand, the smaller external wires wear out more rapi The Market-street Street Railway Company, San Francisco, has used ro 14 in. in diameter, composed of six strands of nineteen steel wires, weigh 21 lbs. per foot, the longest continuous length being 24,125 ft. The Chica City Railroad Company has employed cables of identical construction, longest length being 27,700 ft. On the New York and Brooklyn Bridge cal railway steel ropes of 11,500 ft. long, containing 114 wires, have been used of about 31⁄2 in. in ands of seven or ifn. to 31⁄2 in., and the ed States, however, eing more flexible; rout more rapidly. sco, has used ropes teel wires, weighing The Chicago 25 ft. al construction, the oklyn Bridge cablehave been used. Plough-Steel Rope. Wire ropes of very high tensile strength, which are ordinarily called "Plough-steel Ropes," are made of a high grade of crucible steel, which. when put in the form of wire, will bear a strain of from 100 to 150 tons per square inch. Where it is necessary to use very long or very heavy ropes, a reduction of the dead weight of ropes becomes a matter of serious consideration. It is advisable to reduce all bends to a minimum, and to use somewhat larger drums or sheaves than are suitable for an ordinary crucible rope hav ing a strength of 60 to 80 tons per square inch. Before using Plough-stee Ropes it is best to have advice on the subject of adaptability. 227 |