The next subject in chronological order that is connected with locomotion is but little calculated to advance the general welfare ; but there are some of our readers to whom it may prove sufficiently interesting and amusing. It is a very ingenious modification of Bmnton's mechanical traveller, described at page 398, and is the subject of a tent granted to Mr. John Baynes, a cutler, of Sheffield, in September, 1819. The mechanism is designed to be attached to carriages for the purpose of giving them motion by means of manual labour, or by other suitable power. It consists of a peculiar combination of levers and rods, represented in the following drawing, in which a and b, are treadles moving upon joints, and having slips or openings about two-thirds of their length, for the legs and rods to move in; c and d are lep or crutches, which Baer against the ground as fulcra, by which the carriage is moved forward; andf are rods which support the legs; g and h are double rods, by which each treadle is connected to its leg; the leg c, the supporting rod e, and the treadle rods g, are joined together by a pivot at i; the leg 4 the supporting-rod f, and the treadle-rods h, are joined together at the pivot k. The mode of orating is described as follows :—" Press upon the treadle a, when the rods g will bring down the pivot i with the leg c, the rod h and the rod g into the situation repre sented in outline; the carriage being connected to the leg c by the rod e, will, by the action of the leg and rods, be impelled forward. At the same time, by pulling a cord 1(which passes through a pulley-block m, and is connected at its two extremities to the rods, e and f, by the arms a and o) the leg 4 the rod f, the rods h, and the pivot k, will be brought up to the situation of c e g and i respectively, ready for a stroke of the treadle b, which being then raised, will again impel the carriage." The patentee also states that " there may be several sets of the machinery above described for working each set with a treadle ; or even only one set and one treadle ; but I prefer two for ordinary purposes, par. titularly when only a single person is intended to be conveyed in the carriage, who may work the same by placing one foot on each treadle, in which the action will be alternate. The lower parts of the leg should be so formed or shod as not to slip upon the ground. This machinery may be variously applied to carriages, according to circumstances, so as that the treadles may be worked either belfind or before the carriage, still producing a forward motion; in some cases it may be advantageous to joint the front end of the treadles to the car riage, and press the feet on the hind ends." Our common roads, although constantly undergoing ameliorations, have not yet arrived at that degree of excellence to enable such machines as the foregoing to be worked by manual labour advantageously ; but wo look forward to the period when (owing to the spirit of emulation that will be excited by the suc cess of the railway system) the resistance to the motion of wheeled carriages on the public highways will be reduced to half its present amount; which will render manual locomotive carriages, in many cases, not only practicable, but highly convenient and useful to their private owners. We would not, however, be understood as inferring that such motive force can ever come into successful competition with steam or even horse-power, as a means of public transport ; nor that such a machine as Mr. Baynes's is calculated to apply human strength in the most favourable manner. Hereafter we shall have more to remark on this subject.
Although the invention of Mr. Hawlu, described at page 409, was exceedingly ingenious, and the execution highly creditable to the mechanical skill of our " workers of iron," its success, as applicable to the construction of railways, was of short duration ; for in October, 1820, the specification of Mr. John Birkin thaw, of the Bedlington Iron Works, in the county of Durham, was enrolled for a mode of constructing rails entirely of malleable iron, the process of which is so simple, and the result so excellent, as scarcely to leave any thing more perfect to be desired; all the bars of our present edge-railways are made by this pro cess, and are but slightly modified in form. Previous to Mr. Birkinshaw's improvethents, the edge-rails were chiefly of cast iron, resembling, for the most part, those described under Messrs. Loch and Stephenson's patent ; and those which were formed of malleable bars were of the sectional shape, designated in the annexed figures in the margin, the first being technically called, flat, and the second square bars.
Mr. Birkinshaw's attention was first drawn to the subject of substituting malleable for cast iron rails, by reading a Report made by Mr. Stevenson at that time, on the Edinburgh Rail way. At page 26 of that Report, the author remarks, " One pomt, however, deserves particular notice here, as likely to be attended with the most important advantage to the railway system, which is the application of malleable iron instead of cast iron rails. Three miles and a half of this description of
railway have been in use for about eight years on Lord Carlisle's works, at Tindal Fall, in Cumberland, where there are also two miles of cast iron rail; but the malleable iron road is found to answer better in every respect. Experiments with malleable iron rails have also been made at Mr. Taylor's Works, at Ayr, and Sir John Hope's, at Pinkie ; and, upon the whole, this method, as in the case of the Tindal Fall Railway, is not only considerably cheaper in the first cost than the cast-iron railway, but is also much less liable to accident. In the use of malleable iron bars, the joints of the railway are conveniently obtained about twelve feet apart, and three pedestals are generally between each pair of joints." Previous to, and at the period of Mr. Birkin shaves patent, a considerable degree of prejudice existed against the use of malleable iron rails, on account of their supposed liability to waste by rust. To settle this question by the test of experience, the arnt of the earl of Carlisle, at Tindal Fell (where extensive hnes of both kinds of rails were in use, as already mentioned) was applied to for information on the subject. In a letter dated May, 1819, to Mr. Birkinshaw, that gentleman said—" Our rails are one and a half inches square, and stand upon stones 'about ten inches square, and are placed at one yard distance from centre hole to centre bole. Our railway carries four tone weight, and has never cost us any thing yet, as to expense of the malleable iron, except creasing. The iron I cannot see the least alteration with, although it has now been laid eight years. The cast iron is a daily expense; it is breaking every day." The causes of the preservation of malleable iron bars, expaed to the weather, from rust, and their slow wear, may be readily supposed to be the constant friction to which they are subjected by the traffic, and to the condensation of the upper surface of the metal by the heavy weights rolled over it, which produces La hard compact coat, like that produced by cold hammering steel and copper plates. The facilities which cut iron presents, of enabling the engineer readily to mould and run it into such forms as will com bine the utmost strength with the least quantity of material (individually con sidered), made it, for a long time, a favourite ; but the necessity of guarding against breakage, owing to the brittleness of the substance, occasioned them to be made so much heavier than the malleable, as to render the latter even of less first coat than the cast metal. It was from considerations of this nature that. Mr. Birkinshaw was induced to attempt those improvements that are described in his specification ; an extract from which we shall now make, it being particu larly worthy of notice, as it is descriptive of the fiat and perfectly successful attempt to roll iron ban of those varied and useful forms, which so much abridge the labours of the smith and engineer, and give a higher degree of excellence to the products of their workshops :— " My invention consists in the adaptation of wrought or malleable iron bars or rails of a peculiar form, instead of cast-iron rails, as heretofore. From the brittle nature of cast iron, it has been found, by experience, n to make the bars of a railroad sufficiently strong to bear at least six necessary weight intended to be carried along the road, by which the original cost of a railroad was considerably augmented ; or if light rails were need, the necessity of fre quently repairing entailed a heavy expense upon the proprietors. To obviate these objections, 1 have invented a bar to be made of wrought, or malleable iron, the original coat of which will be lees than the ordinary cast iron reds or bars, and, at the same time, will be found to require little (if any) reparation in the course of many years. The rails or bars which I have invented are formed as prisms, though their sides need not of necessity be Sat. .Figs. 1 and 2 show sections of the bar thus formed ; the upper surface upon which the wheel of the carriage is to run is slightly convex, in order to reduce the friction ; and the under part rests in the supporting-blocks, chairs, rests, standards, or pedestals, which are mounted upon the sleepers. The wedge-form is proposed, because the strength of the rail is always in proportion to the square of its breadth and depth. Hence this form possesses all the strength of a cube equal to its square, with only half the quantity of metal, and, conse quently, half the cost. Sufficient strength, however, may be still retained, and the weight of metal further reduced, by forming the bars with concave sides, as shown in section, by Feet's. 3 and 4. The mode of making iron bars of a great variety of forms, we have already generally explained in our account of the iron manufacture. See litox.