THE MOST IMPORTANT DISCOVERIES AND IMPROVEMENTS IN MECHANICS AND THE USEFUL ARTS; NATURAL PHILOSOPHY; Building for the International Exhibition, 1862.-(See page 13.) LONDON: LOCKWOOD AND CO., 7, STATIONERS' HALL COURT. WILLIAM FAIRBAIRN, C.E., F.R.S., LL.D. (With a Portrait.) THE characterization of the Ages of the World by association with its Metals was a favourite myth of the Greek and Roman poets. They had their Age of Iron, deemed to have commenced long before the day of Hesiod, who lived, probably, at least twenty-six hundred years ago; but this was merely a general name for the existing order of things, as distinguished from some imaginary previous state. This poetic painting, however, consisted but in slight varieties of shade, and had little or nothing to do with the history of the actual world. Tubal Cain was, ages before the time of Moses, 66 an instructor of every artificer in brass and iron." The art of smelting iron was known in England during the time of the Roman occupation; in the Middle Ages, and down even to a late date, the forges of Kent and Sussex were all aglow with smelting and hammering the iron of their soil; then came the smelting with coal, and the blast-furnace; the mighty power of the steam-engine superseded the descendants of Tubal Cain in working the metal, and thus the Iron Age became applied to the stupendous realities of our own time instead of being borrowed from the poetic myth of the antique world. Among the thinkers and workers in our Iron Age, William Fairbairn is entitled to high rank,-presenting a combination of the theoretical and practical man, such as is rarely to be met with. He was born at Kelso, on the north margin of the Tweed, in 1789, and was brought up as a mechanic at Newcastle-upon-Tyne. In 1817, he commenced business in Manchester, in partnership with Mr. Lillie, and the firm soon rose into the very foremost position in the trade of that city; and when this partnership was dissolved, Mr. Fairbairn continued the business. About the year 1830 or 1831, he commenced various trials as to the forms of vessels, and employed a small iron vessel for that purpose. The success of his experiment emboldened him to proceed, and by 1836, he ventured on the construction of iron vessels of considerable tonnage. Mr. Fairbairn was one of the earliest members of the British Association for the Advancement of Science, to whose Proceedings he has contributed some valuable papers on engineering, his great subject being "Iron." In 1837, he read to the Association an elaborate Report on the Comparative Strength and other Properties of Cast-iron, manufactured by the Hot and Cold Blast respectively; in which were employed irons of fifty sorts.* In 1840, Mr. Fairbairn read to the Association a paper on Iron Shipbuilding, wherein he went into the extent to which the strength of iron plates was affected by the rivet-holes; and the general deduc *See Arcana of Science and Art, 1838, pp. 93-97. Also, Year-Book of Facts, 1840, p. 85. tion made from his experiment was, that there was a loss equal to about 32 per cent. As to the comparative strength and safety of iron boats, it seemed to be a general opinion that they were preferable to wood in most respects; and Mr. Fairbairn then predicted that iron would entirely supersede wood in the course of four or five years. * In 1847, Mr Fairbairn patented his method for the Construction of Hollow Wrought-Iron Beams: the mode is to form the beams of stout plate-iron, riveted at the points to strong T-iron, and at the angles to L-iron, to give additional strength, and prevent buckling and deflections as much as possible. A transverse section represents three chambers, the two square ones at top being together rather wider than the upright one, and all bolted together in the most substantial manner. In his specification for these hollow beams, he describes them under different constructions, suitable for mills, factories, warehouses, dwelling-houses, bridges, &c.t When Mr. Robert Stephenson had resolved upon the construction of his Tubular Railway Bridge for crossing the Menai Straits, he confided the experiments to be made upon the strength of iron for that purpose to Mr. Fairbairn, who was considered to possess more practical experience of the power and strength of cast-iron than any other individual. With Mr. Fairbairn was associated in these experiments, Mr. Eaton Hodgkinson; and subsequently, Mr. Stephenson added one of his own confidential assistants (Mr. Edwin Clark), who regularly recorded, and reported to Mr. Stephenson the result of every experiment. Mr. Fairbairn was appointed assistant-engineer by the Railway Company, on the 13th of May, 1846: a claim was subsequently made by Mr. Fairbairn to the idea of the self-supporting Tubular Bridge; a strong controversy ensued; and all who take interest in the matter will find it fully discussed in Sir F. B. Head's very clever Highways and Dryways, and in Mr. Fairbairn's Truths and Tubes, to which Mr. Stephenson's caustic champion, Sir F. Head, subsequently replied through a newspaper channel. Previously to the experiments instituted for this bridge, observes Sir F. Head, "it had been long considered almost a mechanical axiom, that iron possessed a greater power to resist compression than extension," whereas it was discovered by Mr. Fairbairn, that, "after bearing a certain amount of weight, the resisting properties of cast and of wrought-iron are diametrically opposite. Cast-iron can resist per square inch-compression of from 35 to 49 tons; extension of from 3 to 7 tons. Wrought-iron can resist per square inch--compression of from 12 to 13 tons; extension of from 16 to 18 tons." If these experiments had not been instituted, the tubes would have been erroneously constructed stronger at the bottom than at the top, which might have lead to disastrous results. Tubes were constructed of circular, elliptical, and rectangular forms, and, after 40 experiments, their relative strength might be thus expressed in figures -13; 15; 21. The rectangular form being prodigiously stronger. *Year-Book of Facts, 1811, p. 70. Mining Journal: Year-Book of Facts, 1848, p. 57. It than the others, was adopted. The word tube has been objected to, as suggesting a round pipe; tubular is more correct, since the whole strength of the bridge resides in the tubular top and bottom. may be ascertained, by a simple calculation, that a solid bar of iron -could such a thing be made-of the same length, breadth, and depth, as one of the large tubes, would not even bear its own weight! The experiments by which the stability of these Cyclopean bridges was thus secured, called into exercise by Mr. Fairbairn and Mr. Hodgkinson a union of the highest mechanical and mathematical skill, and not merely sufficed for the immediate purpose, but have effected a sure basis for the labours of succeeding engineers. The result was the demonstration that the greatest amount of strength would be obtained by giving to the materials the form of a hollow quadrangular beam or girder, somewhat larger in section in the centre than at the ends, and making the top and bottom, (or the floor and roofs,) instead of being solid, to consist of shallow tubes or cells.* How fertile a principle this has proved need hardly be pointed out it is to having been constructed on this principle that the Great Eastern steamship owes its enormous strength. Mr. Fairbairn was an active promoter of the Great Exhibition of 1851, as a juror and an exhibitor: among the contributions of his great establishment at Manchester, (W. Fairbairn and Sons,) were a six-horse power steam-engiue; wrought-iron tubular crane; inside cylinder tank locomotive engine; and a model of a tank locomotive engine. The firm also sent their important and original machine for riveting boiler-plates by pressure; and their corn-mill on a castiron frame with gearing, showing their improvements in the modes of driving, adjusting, and feeding the millstones. For this machine and mill Messrs. Fairbairn received the Council Medal. In the same year (1851) Mr. Fairbairn read to the British Association a most important paper, "On the construction of iron vessels exposed to severe strain," including the results of his experiments on the resistance of malleable iron plates, beams, and angleirons; continued, from time to time, for improving the construction of malleable iron bridges, boilers, and other vessels, such as caisson and sheet-iron pipes, coming into more general use for pump-trees and other articles connected with mining. A variety of plates from Low Moor, Staffordshire, and other parts, were submitted to direct experiment; first, by tearing them asunder in the direction of the fibre; and secondly, across it: the strength proved uniform, probably from the superior manner in which the article is now manufactured. The experiments were completed, by results as to the process of riveting, by which it is now proved, one-third of the strength is lost. In conclusion were shown several important improvements in steam-boilers, by gussets to strengthen the flat ends and retain them in shape.+ The strength of Iron Ships was also ably illustrated by Mr. * See the papers by Professor Cowper in Year-Book of Facts, 1851, pp. 37-39. See the paper in Year-Book of Facts, 1852, pp. 34-36. |