The formation of the tramway on the Commercial Road gave Mr. Walker another opportunity of proving the absolute wear and comparative hardness of granites. The experiments were made on pieces of the tram-stone 18 inches wide and a foot deep, which, after being accurately weighed, were laid down in one of the toll-gateways where all the traffic from the East and West India Docks uniformformly passed; on being taken up, the stones were again weighed, and the results were as under: * Budle is a whinstone from Northumberland; the others are all granites. + Herm is an island adjoining Guernsey. The second of the above series may be considered the more correct, from the longer duration of the experiment, and from the dressing of the stones of the different descriptions at the time of the first series not being quite equal. Remarks on Horse Railways, and Tramways, by John Macneill, Esq. Railways worked by horses are becoming very general; some have been constructed both in Scotland, England, and Wales, and others are about being formed in Ireland to a very considerable extent. These lines, though worked by horses, have edge rails similar to the best description of locomotive railways, but of less dimensions; they should therefore be called horse railways, not tramways, which, as before stated, are constructed in a very different manner. A railway worked by horses possesses many advantages; in the first place, a horse will be able to perform nearly ten times as much work as he could on a common road, and the expense of construction is so moderate, when compared with locomotive railways, that they may be introduced into districts and countries where the trade and commerce would not justify such an expenditure, even if a sufficient capital could be raised for the purpose. They are certainly more adapted for the carriage of goods and agricultural produce than for the carriage of passengers where a very speedy transit is required; but where 9 or 10 miles an hour are sufficient, they are admirably adapted for a passenger trade, as proved on the Edinburgh and Dalkeith railway, and several others, and at that rate of velocity will probably be found to be the most economical mode of conveying passengers that has yet been introduced. The first cost of such railways will be found to vary from 3,000l. to 5,000l. per mile, according to the nature of the country through which they are carried; the total mass moved in a train of waggons drawn by one horse being so small as compared with the mass moved by a locomotive engine, that the increase of resistance, arising from gravity on an acclivity, bears but a small proportion to the increased resistance arising from the same cause on a locomotive line, and is therefore more within the compass of the moving power. The rates of acclivity may therefore be much greater on the former than on the latter description of railway; and the cuttings and embankments, which are the most expensive part of railways, may therefore be much less, and the cost of construction consequently reduced. The rails may also be of much less weight per yard; on locomotive lines the rails should weigh from 60 to 70 lbs. per yard; as they have to carry the weight of the engine, which is often made to weigh from 8 to 12 tons, and the rails must be proportionably strong, though the waggons which carry the goods or passengers would not require rails of half these dimensions. The wear and tear on the horse railway will be much less than on the locomotive line, for the power which propels the waggons in the former case does not touch the rails, or do any injury to them; whilst, on the contrary, the propelling power on the locomotive railway causes the greatest amount of annual repair and expenses. The effect which a horse can produce on a railway of this description will be seen from the following table. The power assumed for a horse moving at the rate of three miles per hour is 150 lbs., and 70 when moving at the rate of ten miles an hour, and working short lengths, as in mail coaches. Tramways, or what should more properly be called trackways, formed of flat metal plates without ledges, or of blocks of granite, have been used with considerable advantage, and have of late been introduced with considerable success. These trackways are more applicable to general traffic in the streets of towns, and on quays, wharfs, &c. than the edge rail, or tramway; but where they are likely to become most useful is on the sides of the present turnpike roads, where they may be adopted with the greatest public advantage. The trackway in Glasgow is composed of plates of cast metal laid on stone supports, and flush with the surface of the road. They are about two inches thick, three feet long, and eight inches wide. They are laid on a part of the street which rises 1 in 20, yet on this steep incline horses drew up 4 tons with apparent ease. The expense of keeping this road in repair is very trifling. Trackways of granite have been lately laid on the turnpike road between Coventry and Nuneaton, and are found to answer exceedingly well. In this case, as the horses work two abreast, they are obliged to travel on the stone tracks, as they work in the lines of the wheels; in the others already mentioned, the carts or waggons are drawn only by one horse in the shafts, by which means he travels on the pavement between the lines, and not on the tracks themselves. This, however, produces no inconvenience whatever, and no obstruction to the horses from slipping or any other cause. On this trackway the blocks are of granite 12 in. x 9 in. and 34 feet long; the space between the lines is not paved. The work cost at the rate of 1,5197. per mile. A trackway is about to be laid down on part of the Holyhead road, the specification for which is given in another part of this work, and when finished will perhaps be the most perfect one of the kind hitherto made. That part of the road on which it is to be constructed is gene rally very soft, and difficult to draw over, arising from the nature of the soil and the limestone used in repairing it. The power required to draw one ton over a horizontal part of it was found by experiment to be 150 lbs., and on the acclivity of 1 in 20, 294 lbs. When the trackway is laid the horizontal draught will be reduced to 13 lbs., and the draught on the acclivity of 1 in 20 to 131 lbs. This is equivalent to reducing the acclivity from 1 in 20 to a horizontal, supposing the surface of the road to remain as it was when the experiment for ascertaining the force of traction was made. As the part of the country where this work is to be executed is a considerable distance from granite quarries, the work will be expensive; perhaps as much so as in any part of England. The expense of similar works where granite could be procured at a moderate rate would be much less, as will be seen by the following detailed estimate of one running yard of the proposed work. Getting out earthwork and drains 11 yard sandstone and coating, at 1s. 6d. 1 yard of limestone broken, at 3s. yard of Huntshill broken, at 8s. Blocks of granite, at 3s. 9d. per cubic foot Workmanship, pitching, grouting, ramming, laying blocks and curbs Total expense of one running yard 0 2 0 1 0 1 6 3 |