SECT. VII. Machines of Deportation. 2743. The carriage or conveyance machines of agriculture are chiefly carts and waggons, and their several varieties. SUBSECT. 1. Carts. : 2744. Carts, like other implements, vary in their forms and modes of construction, according to the nature and situation of the roads, and many other local circumstances; but, for the purposes of farming, those of the single-horse kind are in general the most advantageous and useful. The advantages of single-horse carts, Lord R. Seymour observes (Ann. Ag. xxvii.), are universally admitted, wherever they have been attentively compared with carriages of any other description. A horse, when he acts singly, will do half as much more work as when he acts in conjunction with another; that is to say, that two horses will, separately, do as much work as three conjunctively this arises, in the first place, from the single horse being so near the load he draws; and, in the next place, from the point or line of draught being so much below his breast, it being usual to make the wheels of single-horse carts low. A horse harnessed singly has nothing but his load to contend with; whereas, when he draws in conjunction with another, he is generally embarrassed by some difference of rate, the horse behind or before him moving quicker or slower than himself; he is likewise frequently inconvenienced by the greater or less height of his neighbour: these considerations give a decided advantage to the single-horse cart. The very great ease with which a low cart is filled may be added; as a man may load it, with the help of a long-handled shovel or fork, by means of his hands only; whereas, in order to fill a higher cart, not only the man's back, but his arms and whole person must be exerted. To the use of single horses in draught there can be no objection, unless it be the supposed necessity of additional drivers created by it: the fact however is, that it has no such effect; for horses once in the habit of going singly, will follow each other as uniformly and as steadily as they do when harnessed together; and accordingly we see, on the most frequented roads in Ireland, men conducting three, four, or five, single-horse carts each, without any inconvenience to the passengers: such, likewise, is the case where lime and coal are generally carried upon pack-horses. In some of the northern counties of Britain also, one man manages two or three, and sometimes more, one-horse carts. 2745. Carts drawn by one horse, or by two horses, says a writer whose authority is unquestionable (Supp. Ency. Brit.), are the only farm carriages of some of the best cultivated counties, and no other are ever used in Scotland. Their load depends upon the strength of the horses, and nature of the roads; but, in every case, it is asserted that a given number of horses will draw a great deal more, according to some one third more, in single-horse carts than in waggons. Two-horse carts are still the most common among farmers in Scotland; but those drawn by one horse, two of which are always driven by one man, are unquestionably preferable for most purposes. The carriers of the west of Scotland usually load from a ton to a ton and a half, on a single-horse cart, and no where does it carry less than 12 cwt. if the roads are tolerable. 2746. Wheels, such as are broad, with conical or convex rims, are common in England; in Scotland the wheels are generally narrow, though broader ones are beginning to be introduced. Those used for the common, or two-horse, carts, are usually about 4 feet high, and mounted on iron axles. The advantages of broad cylindrical wheels have been illustrated with much force and ingenuity in several late publications. (Communications to the Board of Agriculture, vol. ii. and vol. vii. part i.) 2747. Large wheels to carts, drays, &c. will, besides greatly increasing the facility of draught, tend to lessen the number of accidents to which all two-wheeled carriages are liable, from the shaft-horse falling down. To render this more evident, let us first examine fig. 380., which is a rude sketch of a cart constructed in the usual manner, 380 a and supposed to be loaded with bricks, stone, sand, or other heavy material. While thus loaded, and the horse is in an erect position, the centre of gravity (g) is almost directly over the axletree, in which state the body of the cart is nearly balanced, or only pressed upon the back of the horse with a force equal to a few pounds' weight. But the horse is supposed to have fallen: the consequence is, that the centre of gravity is thrown much more forward; the body of the cart and its load becomes divided by the line a b, perpendicular to the axletree, into two very unequal parts, c and d; the whole of the increased portion (c) in front of the line acting as a weight upon the horse, and only partly counterbalanced by the diminished portion (d) behind the line. It frequently happens that this increased weight, so suddenly thrown upon the shafts, snaps them short off'; and, at all times, tends to prevent the horse from rising until part of the load is removed. By adopting the larger wheels, and the bent axle (fig. 381.) the cart, &c. becomes much less liable to such accidents, because the 381 b centre of gravity (g) and the centre of suspension (the axle) are brought much nearer together; the former being placed nearly over the latter, at a small distance only from it. A horse falling with a loaded cart so constructed, will experience but little increase of weight upon him while down: the cart will be divided as before, by the line a b, into two parts; but it will be observed, these portions differ but little in their respective magnitudes. The centre of gravity (g) will be thrown forward, but in a very trifling degree. In carts, &c. it will almost always happen that the centre of gravity will be above the point of suspension (the axle); but in gigs, &c. the body may be placed so low that the centre of gravity may fall below that point, when the body will always maintain an erect (ie. a horizontal) position, and, should the horse fall down, will operate to lift him up again. A gig so constructed would be almost beyond the possibility of those serious, and frequently fatal, accidents, which occur from the falling of the horse. (W. Baddeley, jun. in Mech. Mag. vol. xii. p. 204.) 2748. The power of wheels has no dependence on the height of the wheels, or the length of their spokes, but depends wholly on the power of draught that is joined to their axles, and to the forward motion, or the progress of the carriage. If the carriage were placed upon skates completely polished, and upon smooth ice, it would be drawn by as little power as if it were placed upon wheels. The use of wheels is to lessen the resistance to the carriage by friction, or rubbing upon the ground, or upon the floor upon which the carriage is to be moved; that resistance is least of all when the ground is hard and smooth, such as a rail-road of iron; it increases upon soft and upon rough ground; and it increases still more when the carriage must be drawn up an ascent, according to the steepness of the ascent, because the power of draught must be able to lift the carriage, it may be said, step by step, up the ascent; and when the ascent is soft or rough, more power of draught is necessary. When the wheels are dished they plough the soft ground, and grind the rough ground, and thereby they increase the power of resistance, and require more power of draught to overcome the absurdity of their own form; and thus they cause the continual shaking of the joints of the carriage, and the wearing of the iron and of the wood of which it has been made. Narrow wheels are drawn rather more easily through small loose stones; but, upon every other kind of ground, broad wheels that are rollers are drawn more easily, or with less power, and the benefit of them to the roads is greater according to their greater breadth. High broad wheels do not sink so deep into soft ground as low wheels do; but, if the low wheels be made broader, the benefit obtained will be in proportion to the additional breadth. The axles of high wheels turn seldomer round, or the wheels turn seldomer round the axles, which is an advantage; but high wheels must be weightier than low wheels, which is a disadvantage. High wheels are useful to carry great stones, or great trees, under the axles; and loads of every kind, alive as well as dead, ought to be hung as low as possible. And every load ought to be hung, or to be placed, upon springs, which will allow the carriage to be lighter; and the lower it is hung, or placed, it will be so much safer from overturns, there will be less shaking, and less power of draught will be required. (Sir Alex. Gordon, in Farm. Mag. vol. xx. p. 150.) 2749 The construction of wheels has been much improved by the introduction of cast-iron naves or stocks These stocks are found particularly suitable for warm climates, and scarcely any others are exported. Messrs. Morton, of Leith Walk, have renewed the spokes in them after they have been in use twenty years, and found the stocks as good as when new. (Gard. Mag. vol. vi.) In England wroughtiron spokes have been employed, which are found to succeed perfectly, and, from their durability, will, in the end, be found cheaper than wood. 382 2750. Jones's improved iron wheels (fig. 382.) are formed wholly of cast and wrought iron. The felly, or periphery of the wheel (a), is made of cast iron, with conical holes on the outside, contracting towards the centre, through which the spokes, made of iron rods, are to be passed, and secured in the box, or nave (b), near the centre of the wheel, by nuts screwed on to the reverse end of the rods, by which means they are drawn tight. (Newton's Journal, vol. i. 2d Series, p. 154.) 2751. A great improvement in the construction of axles for carriages, carts, and waggons, has been made by George Burges, Esq. M. A. of Cambridge. Instead of one circle moving within another, as in all common axles; or one circle moving within another, this other 383 having grooves for retaining oil in the manner of the patent axles; Mr. Burges's axle is a circle (fig. 383. a) moving within six points, formed by six equal convex segments, which hold oil in their angles (b): the friction is thus reduced to a minimum in theory; and with case-hardened iron, and abundance of oil, we should think it could not be otherwise in practice. Mr. Burges has had the axles of his own carriage constructed in this way for some years. (Gard. Mag. vol. v.) 2752. The Scotch one-horse coup cart is used either building on a greater load of hay, straw, or corn in the sheaf. This frame is held on by no fastening, but remains in its place from being fitted to the exact width of the body of 384 the cart. On drawing out an iron pin, the fore part of the body rises up from the shafts, while the other end sinks, and allows the load, whether of dung, earth, or stones in the close cart, or of hay, or sheaves of corn, on the cart and frame, to fall to the ground. 2753. The Scotch corn cart (fig. 385.) consists of open framework, with a boarded 385 bottom, and is used solely for the purpose of carting hay, corn in the sheaf, or similar materials. It is light, cheap in construction, and contains a bulky load, which, being lower and more extended than a load on a coup cart with a frame, is less likely to be overturned. 2754. The Scotch two-horse cart differs little from the one-horse cart, except in being larger. To prove the inferiority of double to single horse carts, Gray observes, "that whatever greater part of the load is placed before the centre of gravity, which is always in the axle, must rest constantly on the horse that is in the shafts. In going down hill this burden must be considerably increased, especially if the load be high above the centre of the axle, or the descent steep; and the additional burden upon the shaft-horse is always in proportion to these two causes united. But there is another disadvantage; for, unless the line of the draught of the foremost horse be exactly in the line from the hook of his collar to the centre of the axle (which is hardly possible), he will perpetually be pulling down the hindmost horse, or, in other words, will be giving him more weight to carry. For, as the traces of the foremost horse are generally fixed upon the shafts, this throws his line of draught at a considerable angle above the centre of the axle; from which it is evident, that although the road be ever so level, yet in every double or two-horse cart, the foremost horse must either not draw at all, or must bring additional weight upon the horse in the shafts, which weight will always be in proportion to the force with which the trace-horse draws, and the largeness of the angle which the line of his draught makes with the line from the hook of his collar to the centre of the axle. Besides, unless the driver be more careful than ordinary, and keep the trace-horse to his duty, the other one has not only this great weight to carry, but also the whole load to draw. The angle is increased considerably when the trace-horse is of a lower size than the one in the shafts, which may frequently happen; and, by this means, a still greater burden is laid upon the back of the horse employed in the shafts. 386 2755. Improved two-horse carts. (fig. 386.) It may be suggested to those who are fond of employing two-horse carts, that, in order to adjust the traces of the fore-horse with as little injury as possible to the one behind, and by this means make both their powers coincide, two iron frames are fixed into the axle, in each of which is placed a sheeve or whorl. Upon these sheeves pass a rope or chain (a). In the outside of each shaft is fixed a long iron staple; and on each staple is placed an iron slider (6), having liberty to shift either forward or backward; the chain from the collar of the shaft-horse is hooked into the eye of the slider; and the chain or rope, by which the foremost horse draws, passing from his collar (c), round on the sheeve at the axle, is hooked into the other eye of the slider. By this means the two horses are so connected, that, if the one shall relax, immediately the exertion of the other horse presses the collar hard upon his shoulders, so that he must either exert himself or be pulled backwards. Thus the exertions of the two horses are united, so as to form one power applied to the cart, in place of two powers working generally against one another, which must be the case in the common way of attaching two horses to a cart. But, by this way of yoking, the shafthorse receives no additional burden from the exertion of the trace-horse, as they both draw from one point, which is the centre of the axle, to the hooks of their respective collars, by which their powers must nearly coincide. If this coincidence does not take place, it is evident that the two horses will, to a certain degree, be pulling against one another, which must be extremely distressing to each in his turn, especially to the one in the shafts. The same principle, as will afterwards appear, has been employed in yoking horses to threshing machines. 2756. The corn cart has a longer body than the close cart, and the sides and ends are cpen, and support two rails along each. It is made to fit the axle and wheels of the close cart, and is chiefly used in haytime and harvest, when it is supposed to admit of laying on a larger load of sheaves or hay than the cart and frame. 2757. Lord Somerville's drag-cart (fig. 387.) is constructed with a contrivance for 387 checking or regulating the rapidity of its motion in going down hills or other declivities. The method for adjusting the position of the centre of gravity of the load, and to prevent its pressing too much on the cattle in going down hill, is by a toothed rack, screwed to the front of the cart, and worked by a pinion and handle (a) immediately connected with the pole. By means of this pinion and rack the front of the carriage is elevated more or less, in proportion to the declivity of the hill, by which means the weight of the load is made to bear more on the axis, and less on the necks of the oxen. A friction drag (b) is made to press more or less on the side of the wheel, according to the steepness of the descent; the one end of it is connected with the tail of the cart by a small chain, and the other end to the front, by means of a toothed rack, which catches on a staple in the front of the cart, by which the pressure of the friction-bar may be regulated at the discretion of the driver: the notches or teeth in this rack, it is observed, should be as close to each other as circumstances will permit. 2758. The advantages of the friction-drag, and other contrivances, are said to be, 1st, The method, which is equally simple and expeditious, of adjusting the centre of gravity of the load, so as to have a proper bearing on the horses or cattle, in going down hill. 2dly, The method of applying friction to the side of the wheel, to regulate the motion of the carriage in going down hill (instead of locking the wheels), the advantages of which method appear to be as follow: namely, first, the pressure and degree of friction may, with great expedition, be adjusted to the steepness of the declivity, so that the carriage will neither press forward, nor require much exertion to make it follow the cattle; secondly, the friction is so applied to the wheel, that a given pressure will have twice the effect in retarding the progress that it would have if immediately applied to the body of the carriage, or to the axis: and, by applying the friction on both sides of the wheel, the risk of heating and destroying the friction-bar is much less than if the same degree of friction were applied in one place. Sdly, This apparatus is so conveniently placed, that it can be instantly applied or adjusted, without stopping the carriage, or exposing the driver to the same danger as in locking a wheel. And, 4thly, This contrivance will assume yet a greater importance when applied to both the hind wheels of waggons, by which means the resistance may always be proportioned to the steepness of the descent, the tearing up of the road prevented, the unnecessary exertion of the cattle in drawing the locked carriage down hill avoided, the danger to which the driver is sometimes exposed in locking the waggon-wheel totally evaded, and the time now lost in locking and unlocking the wheel saved to the 2759. Rapson's stop drag for carriages going down hill (figs. 388, 389, and 390.) con sists of five or more pieces of wood, "united on the outside by a strong jointed iron hoop; the wood pressing upon the nave of the wheel. The first, a fixed pivot (a), from the hoop, is fixed to the under side of the frame of the cart; from the other extremity of the hoop of the brake proceeds a bar (6), which slides through the plate or socket (c) fixed to the side of the cart frame; a vertical perforation is made through the bar (b), just behind the plate, to receive the pin (d), which is likewise chained to the shaft: this pin, so placed, prevents any force applied to the chain from tightening the brake on the nave of the wheel. Fig. 389. represents the interior of a wheel on level ground, the nave surrounded by the brake, which, by its own gravity, is hanging loose, leaving the wheel perfectly free. Fig. 390. shows a wheel on a declivity, the chain drawn tight by the pressure of the breeching on the horse; the brake, of course, closely surrounding the nave, and forming an effectual drag. Fig. 391. is a bird's-eye view of the whole 391 apparatus, exhibiting the framing of the cart, the shafts, wheels, and brakes; the chains also are shown, passing from the bars on each side, each round a horizontal pulley on the shaft, and attached to the ends of the breeching. Thus it is evident that, when a cart, furnished with this drag, is going down hill, the load, pressing the breeching against the horses, draws the brake tight by means of the chain, and produces a friction on the nave proportioned, in some measure, to the declivity. When backing upon level ground, by inserting the pin (fig. 388. d) through the bars of the brakes, the wheels will be kept free. This drag is to be applied to the naves of the carriage wheels, with a chain attached, fastened to the breeching of the horse, and a small pin on each side of the shaft is to go into the hole of the bar of the drag. If one of the pins be taken out, one wheel will be dragged and the other not. By leaving out both pins, the two wheels are dragged in going down hill, by the breeching bearing against the horse. The wheels will revolve round on a level road, and in going up hill undrag themselves. When the wheels are braced, two or three tons' weight have very little pressure on the horse in going down hill. If two loaded carts should meet on a narrow hill, by unhooking the drag-chain from the breeching, and hooking it to the tub-chain (back chain), the horse can be put back with the greatest ease and safety. When the horse is put back against the hill, the two pins must be put in the bars of the drags. The drag consists of a wooden brake, applied round the nave of each wheel, in pieces which are encircled and connected by a jointed iron plate. The small bar attached to one end of this brake slides freely through a corresponding hole in a plate fixed at right angles to the shaft: a hole is drilled through this sliding bar, for the purpose of admitting a pin or forelock, chained to the shaft. To each end of the breeching is attached a chain, which, passing through a horizontal sheeve, or pulley, on the upper surface of each shaft, is ultimately fixed to the bar of the drag. While the bolts or forelocks remain in the holes behind the perforated plate before mentioned, it is evident the brake cannot tighten upon or drag the wheel; but, on either of those pins being removed, the wheels become immovable." (Smith's Mechanic, vol. ii. p. 322.) 2760. Kneebone's drag for two-wheeled carriages (fig. 392.) is composed of a piece of wrought iron, curved to the exact form of the circumference of the wheel, with a chain, to be fastened to the near shaft, to keep the drag properly under the wheel. When the drag is out of use it may be hung on hooks, at the under part of the tail of the cart. The weight of this drag is usually from sixty to eighty pounds. "This simple contrivance has never failed to be effectual in retarding carts, or any two-wheeled carriages, while descending hills, taking off the great burden from the shaft horse, and |