Description of a Railway on a new Principle; with Observations on those hitherto constructed, and a Table, shewing the comparative Amount of Resistance on several now in use: also an Illustration of a newly-observed Fact relating to the Friction of Axles; and a Description of an improved Dynameter, for ascertaining the Resistance of Floating Vessels, and Carriages moving on Roads and Railways. By Henry R. Palmer, Civil Engineer. With Plates. Second Edition, revised.-J. Taylor. 1824.

Remarks on Steam Navigation, and its Protection, Regulation, and Encouragement; in a Letter to the Right Honourable William Huskisson, Treasurer of the Navy, and President of the Board of Trade. By Thomas Tredgold, Civil Engi neer.-Longman, Hurst, and Co. 1825.

HAVING observed the favourable mention of Mr. Palmer's railway, in a treatise on Railroads and Carriages, by Mr. Tredgold, which we reviewed in our last Journal; and Mr. Tredgold having made several quotations from the experiments therein detailed, we were induced to procure the work, that, from a careful perusal, we might form an opinion of its merits. The passage alluded to, is the following:

"The railroad invented by Mr. Palmer is of a novel and ingenious kind. The carriage is drawn upon a single rail, the surface of which is raised about three feet above the level of the ground, yet is supported by pillars placed at equal distances-the average distance apart being about nine feet. The carriage consists of two receptacles or boxes, suspended one on each side of the rail, by an iron frame, having two wheels of about thirty inches diameter. The rims of the wheels are concave, and fit to the convex surface of the rail; and the centre of gravity of the carriage, whether loaded or empty, is so far below the edge of the rail, that the receptacles bang in equilibrium, and will bear a considerable inequality of load, without inconvenience, owing to the charge of fulcrum from the breadth of the rail, which is about four inches. The rail is also made capable of adjustment, so that it may be kept straight and even. The advantages of this arrangement consist in its being more free from lateral friction than even the edge rails; and, the rail being raised higher above the ground, it is much less liable to be covered with dust or any extraneous matters likely to affect the motion of the carriages. Also, where the surface of a country undulates considerably, a rail-way of this kind may be made without cutting to level the surface, except so far as is necessary to make a track that a horse can travel in.

"When horses are employed, a track-rope is required, which ena

bles them to draw without material alteration of the angle of draught, while the weight of the rope serves as a spring to regulate the variable exertions of the horse.

"We expect, that this single railroad will be found by far superior to any other, for the conveyance of the mails, and those light carriages, of which speed is the principal object; because, we are satisfied, that a road for such carriages must be raised so as to be free from the continual interruption and crossings of an ordinary railway. Abcarriage, moving at a greater rate than about six miles per hour, on a railway, must be raised so as to remove the possibility of overrunning people, or of dashing against other vehicles. Carriages running smoothly and rapidly with a small moving power, cannot be checked suddenly; and they admit of no change of direction. But, were a railway elevated ten feet above the common roads, the accidents could not take place, except through neglect; the passengers would not be raised to a much greater height than the top of a common coach, and in a suspended carriage, which could not possibly overturn. A road of this kind would be more free from interruption than any other; and a velocity, sufficient for any useful purpose, may be ob tained at a small expence of power, in a mode pointed out in the fourth chapter. Undoubtedly, a carriage might be suspended from between two rails raised at any height above the ground; and there would be some convenience in this arrangement; but it would be much more expensive, for the rails must be made firm and equi, distant. As to the circumstance of the single rail dividing the riage into two parts, that would, most likely, be esteemed a recommendation."

Having seen the working model at Mr. Smart's, New-road, near Westminster-bridge, referred to in the Preface of the work, we can speak to the correctness of this description; but then, the model is executed in a manner very superior to what would be done by an ordinary workman, on a common rail-way. Therefore, the facility with which the loaded carriages are there moved, could not be realized in general practice, unless attended with greater expence than many persons would be inclined to incur, for the conveyance of any common cheap materials. A railway, on the principle invented by Mr. Palmer, has lately been formed near Cheshunt, in Hertfordshire, by Mr. Gibbs, for the conveyance of bricks, brick-earth, deals, &c. from the river Lea to Cheshunt, a distance of about a mile and a half. A part of this rail-way was opened on the 25th of last June. A train of seven carriages, partly loaded with bricks, and about thirty persons, making a total weight of about seven tons and a half, was drawn up and down the railway. The motion of the carriages was exceedingly smooth and agreeable; several of the scientific gentlemen were observed writing during the time,

and with scarcely any interruption or inconvenience from the motion of the carriages. The rate appeared to be about six or seven miles an hour, or, perhaps, more, when they were at the greatest velocity. It appears that, as a railroad for conveying passengers, the notions formed of it by Mr. Tred gold, in his book on railroads, are fully justified. Indeed, the only objection would be the expense of rendering such a road perfectly strong at the height he proposes it to be placed above the surface; whilst the motives for raising it to such an elevation, seem to be sufficiently strong to warrant the necessary increase of expence.

The construction of the railway executed for Mr. Gibbs, is not so perfect as we should have expected, it being somewhat roughly executed, and the carriages not very well made. One of the carriages was provided with a species of friction-rollers, which did not appear to act as they had been intended to do; and we did not perceive how the friction of the axes would have been reduced by them, if they had acted as intended. Whether it be from imperfect execution, or from some error in the experiments on this railway in model, we know not; but the effect was not so great as that promised in the pamphlet before us; nevertheless, it was equivalent to the effect on the best of other species of railway; and it will undoubtedly be a valuable acquisition to Mr. Gibbs. The posts and rails forming the rail-way, are of timber, and the upper edge of the rail is covered with a thin plate of wrought iron, on which the wheels of the carriage run.

Mr. Palmer's treatise commences with some general remarks on the application of rail-ways, and then proceeds to examine the nature of the different kinds. From an experi ment made on a branch of the Cheltenham tram-road, which was nearly new, and in good condition, with a view to ascertain the difference of resistance, occasioned by dust lying upon the rails, he states, that he found the increase upwards of one fifth. But it appears, that this resistance is somewhat diminished during rain, and it is not unusual to attach an additional waggon to a horse during rainy weather. It was this circumstance which suggested the idea of carrying water in front of the train. We agree with him in his, observations on the several imperfections to which the surfaces of rail-ways are exposed, arising from the deranged position of the foundations, by which the line is rendered irregular, the parallelism of the two lines of rails are destroyed, and, ultimately, repeated fractures and expensive repairs are incurred; and that the adjustment of the rails to their proper position becomes an expensive operation. And though he offers some

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conclusive reasons for avoiding arrangements which are subject to get out of order, yet the inference, that we should employ rails capable of adjustment, is more ingenious than consistent with the economy of a railway. The great object of other engineers has been, and will continue to be, to devise methods which render adjustments as little necessary as possible; and the loss, by a small degree of undulation, will not be equivalent to the expence of the means and process of adjustment. He mentions an experiment on the axle, deserving of notice. Having perceived (he says) that when fresh oil was applied to the axles of the carriages, the resistance was increased, and it required the ordinary motion of the carriage, for several days, to restore the resistance to its usual standard;" and that, when the axle was only moistened with oil, the resistance was found to be similar to what was ob served when the carriage had been some days in motion. Conceiving that the resistance arose from the wedge-like form, which the oil assumed by the motion of the wheel, he had an axle made with the lower half to fill that part of the nave, and reduced the upper half to the segment of a smaller circle, finishing with a line nearly parallel with the radius!" the consequence was, that the space, thus provided, became areceptacle for the superfluous oil, and the resistance was one tenth less than the former standard.

His attention is next directed to the power of a horse in a railway, and the actual resistance of a load on different rail-" ways. To determine these resistances, the author contrived an instrument, with a view of improving the common dynamometer. It consists of restraining the motion of the index, with a view to make it vibrate less; but it is not shewn that its indications will be the mean result of the actions upon it; and, unless that be the case, the instrument is not worthy of confidence.

However, by way of exhibiting the difference of resistance upon different railways, we refer to the Table, in the next page. In each experiment, the power of the horse is assumed at one hundred and fifty pounds, moving at the rate of two miles and a half per hour.

2 Surry Tram-road.

Coals. 39
Chalk. 60

8850
9000

4602 2 1 30.005958 6 -1 92
6750 3 0 30.010000 10 0 100

3 Penryhn Slate Quarries, Edge Railroad, curv ed surface