ROAD STEAMERS.

Wellington Independent, Volume XXVI, Issue 3094, 5 January 1871, Page 4

ROAD STEAMERS.

[From" the Builders' Tbadb Ciroulab.] Edinbubqh and Leith are quite taking tbe lead in the matter of improving our means of ordinary locomotion. We have repeatedly called attention to the road steamers with india rubber tyres, invented and patented by Mr E. W". Thomson, as introducing a new era in regard to both fast and slow traffic on ordinary streets' and roads. The principal novelty — the principle upon which all advantages of Mr Thomson's system depends — is the elastic tyre. By its means all the irregularities of the ground to be passed over are equalized, whether those inequalities are matters of unevenness of surface or difference of hardness or softness. Thus, with an india rubber tyre, it does not seem much to matter whether the engine is passing over a well paved street or a rough country lane, a newly ploughed field, or a hill covered with frozen snow. The tyre gives way sufficiently to compensate for all irregularities, and bites sufficiently to go steadily on up hill, and to prevent slipping down hill. It is one ot those simple ideas that constitute a great invention. Prom our former articles Mr Thomson and our readers can judge how much we appreciate his work, and consequently the following remarks will not be misunderstood. Instead of being satisfied with the principle of his invention, and working it out thoroughly, both by himself and by the general manufacturing engineers of the day, it seems to us that Mr Thomson has seriously compromised his success by complicating this principle with details of engineering that, have nothing to do with it. He seems also to have so involved himself with one manufacturing firm as to prevent others from paying attention to the system, and so improving it in all manner of ways. And these two errors are mutually reacting on each other. For Mr Thomson will only hare one maker, and seems to limit his maker to one system, with one particular construction of boiler and engine. This is very unfortunate, for because many think the boiler and engine defective, they condemn the whole system. Mr Thomson is so wedded to liis copper-pot boiler that we believe he has all his engines made with them. This boiler we regard as wasteful, and not to be depended upon. The steam costs muoh, and cannot be kept up, and perhaps in the middle of a trial the whole affair comes to a standstill. As we said, the real principle of Mr Thomson's invention has nothing to do with all this ; but what does that signify when we cannot get steamers fitted with india rubber tyres unless we take them with pot boilers. It seems to be the weakness of inventors to be thus dissatisfied with the general principle they enunciate until they hamper it with useless and impracticable details. Where would Mr Bessemer's process have been now had not practical -men have taken his principle and eliminated therefrom all the subsidiary processes with which he. hampered it P . Another matter which stands in Mr Thomson's way is the material he has chosen for his elastic tyres. In the abstract there can be % no doubt but that india rubber is the best material one could use for the purpose. But in practice there are grave objections to its use— not objections to it in itself so much as objections founded upon its ciroumstantialities. In the first place its cost is very great — a set of tyres costing nearly £200, we believe. A set cannot be kept in reserve, as to say nothing of letting £200 lie idle in the shape of tyres ; the tyrea deteriorate when not in use. They cannot be readily obtained, as we believe that the North British Rubber Company at Edinburg are the only firm that have appliances for making such immense pieces of india rubber. And lastly, when the tyres are obtained there is the skill and labor to be obtained for putting them on. What this is any one can appreciate who knows what it takes to put on a little rubber friction band on one of Barnard's lawn mowers. But Mr Thomson's is not the only*road steamer for which we are indebted to the ingenuity and intelligence of Edinburgh. And the remarks we have made in reference to his will enable our readers the better to appreciate the engines invented and patented by his friend, Mr A. Nairn, of 21, Albany street, Leith. Now, though the elasticity of the tyre is equally the vital principle in both patents, MrNairn Has not limited himself to one material. The. material he recommends is common hempen rope, and the trials hitherto made prove this material to be perfectly suitable for the purpose, both as regards first cost, efficiency when in use, wear, and facility for repair. In fact, the longer hempen tyres are in use the better they seem to become. They are not liable to get injured, however rough the work they have to dp, and I when they have to be repaired any laborer can do the work with almost, any fibrous material that may be at hand. Different materials are used for the. tyres of steamers intended for different duties. For traotion engines hemp alone is used ; for ploughing engines an elastic material like cork or rubber . is placed between the iron and hempen tyres. All the tyres are Nprotec ted by wrought iron plates. In the engines to which Mr Nairn has applied his patent, he has exemplified the same practical skill as is developed in the tyres. The boilers are upright tubular ones, fitted with Fields' tubes, with a considerable excess of heating surface in proportion, to grate surface and cylinder area so that all the coal and coke consumed is made to do effective work, and plenty of steam is obtained, with a small expenditure of fuel. The engines are very simple in construction and working. The driver has only two handles to look after — the steam and reversing handles. And all complication of clutches and gear by means of slip brakes attached to the wheels is entirely avoided. When in Edinburgh last, we had the pleasure of seeing two of Mr Nairn's steamers. One was a street omnibus that was publicly tried on Thursday, and the other was a contractor's traction engine. Of the latter the general description we have given will suffice. But as regards both, we may remark that the judicious manner in which. the weights have been kept as low down as possible, render them very steady and safe, even when going at comparatively high speeds. The omnibus, in external appearance, very closely resembles one of the largest horsedrawn vehicles. There are only three wheels —two driving ones behind, and a leading or ; steering one in front. Tbe leading or steering wheel works in a central bracket, and is regulated by a worm wheel and worm. The wheels are made of wrought iron, about three feet in diameter, and have tyres of hemp ten inches broad, and make little or no noise. The driving wheels are fitted with friction brakes, and although the whole power of the engines is transmitted' through these brakes, yet in taking a curve, however sharp, the

wheels adapt themselves perfectly to their relative speeds on the curves, thus rendering the engines extremely simple and easy of management. The body of^he carriage is supported on the wheels by a combination of laminated and volute springs, and blocks of india rubber, which makes it swing with perfect ease. A small portion of the fore end 'of the carriage is partitioned off for the boiler, and this partition is formed so as to prevent any heat from the boiler entering the passenger compartment. Under the centre of the carriage a water tank is placed for supplying the boiler. The motive power is applied through three combined cylinders placed under the rear of the carriage, and acting directly on the axle of tho two hind wheels. The engine is six horse-power nominal, and is entirely under tho command of the steersman. All the bearings are made curved, so that swaying on the springs throws no undue strain on any of the working parts. Coke is used in firing the boiler, so that there is little or "no smoke ; and the hot air from the furnace and the exhaust steam are, by an ingenious arrangement carried off noiselessly, and without causing any inconvenience to the passengers. There is no funnel, according to the common acceptation of the term, the hot air and Bteam being conveyed away by a pipe leading from the boiler along the top of the carriage, beneath the seats for outside passengers, and having an exit at the extremity of the weather board over the conductor's head. The pipe through which the hot air and steam pass is inside another pipe or tube, a few inches apart, and through this space a current of cold air is constantly passing, so that no heat can be felt by those outside the 'bus. The engines are managed, and the vehicle steered, by the man seated in front, and the fire can be attended to by a boy. So completely is the omnibus under the control of the engine man, that it can be stopped or started almost simultaneously, and the sharpest curves can be taken without danger. On Thursday the omnibus started from Mr Adamson's Bazaar, Leith Walk, at 2.15, and proceeded under easy steam by London Eoad, Norton Place, Eegent Road, Waterloo Place, to west end of Princes street, returning again by Princes street to ' Register Office, L*eith street, down Leith walk to Bernard street, thence by Junction Road to Caledonian Station ; here it was intended to take in water, but, still having abundance, the route was continued by Annfield, through the narrow street at Newhaven, turning to the left into a very steep hill, better known as the New Cut, thence by tho Ferry Road to Messrs Hawthorn's Works, Leith. During the whole journey there was not a single mishap. It was beautiful to see the perfect command the driver and steerer had over the machine; the difficult corner at Norton Place was taken in splendid style. Another great matter in connection with the working of the omnibus was the absence of smoke and noise, which has all along been a great annoyance to the general public in most engines previously invented. In passing along Princes street this was most observable, not a vestige of either waste steam or smoke was to be seen ; in fact, many of the general public must have wondered what actually propelled the omnibus along. The number of passengers during the whole time was 60, in one instance 55, when a number of porters at the Caledonian Station were allowed on the top. With this heavy load the engine took the gradient at the New Cut, of 1 in 15, with perfect ease, the tyres gripping the road to admiration. Not a single slip was made. AfterJ ascending the hill full speed was allowed on the level road of about 900 yards, when a speed of fully 20 miles an hour was obtained, and could have been kept up for 15 miles without stoppage. No one who experienced the quietness and steadiness of the ride could doubt but that Mr Nairn has introduced a vehicle that completely supersedes the necessity of laying down tramways in our streets. We. commend it to the attention of all companies who have obtained powers to lay down tramways in the metropolis and the larger provincial towns. Is it worth while to interfere with street traffic, as tramways must do, when the object can be better attained at infinitely less cost, both in construction and working expenses P