ARTICLE V. From "Appletons' Mechanics' Magazine," Nov. No. (N. Y.) Steam-Carriage for Plank-Roads and Smooth Pavements. We call attention to the plans of Mr. Fisher for travelling on plank-roads by steam-power. He has been laboring for some twelve years or more on this subject, and has taken measures to secure a patent for the inprovements which, in his opinion, render the project feasible. He will, at his rooms, 179 Broadway, be pleased to exhibit his models and drawings, which are well worth the examination of capitalists about to embark in plank-road construction. The following reports from committees of the American and the Mechanics' Institutes, of this city, will show that the project is favorably regarded by men whose opinions are entitled to the highest consideration. AMERICAN INSTITUTE, The following Report was read, accepted, and ordered on file, viz: Your committee, to whom was referred the consideration of Mr. J. K. Fisher's improvements in plank-road steam-carriages, beg leave to report as follows: The carriage presented by Mr. Fisher embodies a number of new and important improvements, both as regards its general arrangement and the application of steam. He has introduced a new method of working steam expansively, by means*** (we do not give the description, as it might prejudice the inventor's interest in foreign countries). *** We think it highly successful and effective. The arrangement for cutting off the steam at different points of the stroke is equally as effective as the main movement. The combination of the radius and parallel rods, to afford steadiness to the machine, even at high velocities, is certainly a very great improvement, particularly if the machinery and carriage are sustained upon easy springs, as in the arrangement presented in the model. By this arrangement, it should be observed, all the weight of the heavy framing hitherto used is dispensed with, thereby giving greater capacity for carrying passengers." The whole of the machinery, including the apparatus for steering, is so planned that only one person will be required to manage a carriage. We consider the model presented by Mr. Fisher capable, with some slight modifications, of affording a very superior plan for steam-carriages to run on good level roads. (Signed) JAMES RENWICK, Chn., Committee. MECHANICS' INSTITUTE, The committee on Arts and Sciences have had referred to them the improvements in steam-carriages for common or plank roads, by Mr. J. K. Fisher: they appear to possess several advantages over those formerly experimented upon. The cut-off, to work the steam expansively, is a very ingenious contrivance, and is so arranged as to cut off the steam at any part of the stroke; and it would answer for fixed engines, as well as for steam-carriages. The backing or reversing motion appears to be very well arranged. The attaching the engines outside the wheels, as is done in some locomotives, instead of cranking the axletree, as was done in most of the English carriages, is, we think, a decided improvement; and, taking the arrangement altogether, your committee think it worthy of the favorable consideration of the Mechanics' Institute. (Signed) CHAS. W. COPELAND, Com. on Arts and Sciences. The slight modifications alluded to in the report of the American Institute, relate to the apparatus for varying the time of cutting off: they are deemed too complex to bear the jolting of common roads. But, although there is some complexity in those parts, worked only occasionally, which are necessary to vary the cut-off, the whole valve-movement is composed of fewer parts than the movements generally used on locomotives, which do not vary the cut-off, but work either at half-stroke or full stroke. If only the half-stroke cut-off be required, Mr. Fisher's movement can be simplified so that the total number of its parts will be only half that of common locomotive valve-movements, and these parts will be less heavy and complex than those in use. In the common movement there are eighteen principal parts constantly acting, and ten parts occasionally acting, twenty-eight in all; and counting all the subdivisions, screws, nuts, rods, bars, &c., the total number is one hundred and ninety. Mr. Fisher's movement, which has the advantage, important for a common-road carriage, of working at half-stroke with one engine while the other works at full stroke, is composed of twelve principal parts constantly moving, and two occasionally acting, fourteen in all; and counting all the subdivisions, boxes, screws, &c., the total number of parts is sixty-four, only a third of the total number in the common movement, and the parts are smaller, and less subject to jolting. But when it is required to vary the cut-off at pleasure, while the carriage is running, the number of principal parts constantly working will be twenty-two, two more than in the common movement, and those occasionally working will be ten, thirty-two in all; and counting all the subdivisions, one hundred and twenty-nine parts -sixty-one less than in the common movement. And it may be observed, that if the complex part objected to, the geering for timing the cut-off, should be broken, the engines would not thereby be stopped, but would work at full stroke, or cut off at the latest point determined by the construction. And we think that the tenderness of this geering, which works only when the cut-off is to be varied, is not a sufficient reason for foregoing the advantages of a variable cut-off, which will be brought into view in what we have to say upon the subject of working on roads. The practicability of locomotion by steam on common roads is an established fact; several English inventors have run carriages which did efficient service, and were perfectly under control: they emitted no visible smoke or steam; made no noise, except with the wheels; and they were not in any way disagreeable. But their profitableness is a point not yet established. Nor is the contrary proved by their failure to get into general use in England; for there are many reasons, apart from the defects of the carriages, why they should not have done so well there as they might do elsewhere. First, railroads occupy all the long lines of travel. Where capital is abundant, and freight and travel such as they must be with a dense and active population, the hard iron rail makes the most economical road. Second, it is a well-known fact that those carriages were not managed with economy: some required three men to work them, a steersman, an engineer, and a fireman, who, besides his peculiar duty, worked the breaks. And third, a violent opposition from the agricultural interest, prompted by the consideration that they would diminish the demand for horse-feed, continually annoyed, and at last broke down, the projector, Mr. Gurney, who ran carriages in the country. In our country, for years to come, there will be long lines of travel upon which railroads will not pay a profit, owing to the high rate of interest, and the scantiness of the business: upon these lines cheaper roads must be used, as precursors to railroads. And it will be seen by the above report that a carriage may be so arranged that only one person will be required to manage it, thus saving the wages of two men,-which alone would afford a handsome profit on a carriage. As for the opposition of any parties, we apprehend that there is too much good sense to allow it. But there is one new element, in this country, which, above all others, will operate in favor of steam-carriages; we refer to plankroads, which have not been used in England, nor any where until within sixteen years. The power required to draw a load upon them is about a third of what is required upon a good Macadamized road, upon a level; and they are usually graded so as to avoid steep ascents. According to Parnell (Treatise on Roads), a pull of seventy pounds is required to draw a ton upon a Macadamized road in ordinary condition: on a plank-road a pull of twenty-three pounds will draw a ton, even when there is dirt upon it, as is usually the case. But if they were kept clean, as they would be if steam-carriages were in general use, probably a much less pull would serve; for upon stone tracks only twelve and a half pounds will draw a ton. Now hard planks, laid lengthwise, and kept smooth and clean, should not require much more power than stone tracks. We may, therefore, confidently expect that roads of this kind will be laid on the new lines of travel, and be used until the increase of business will warrant the perfecting of the grades, and the substitution of iron rails. Until this time we shall have many roads, suitable for steam-carriages, which will require but one-third of the power required upon the English roads, upon which their steam-carriages worked. The advantage of this may be briefly shown by a statement of the weight and power required to run a small carriage, to carry four to six persons, upon roads of different kinds. Weight of the carriage, six hundred pounds; machinery and water, about four hundred; load, six hundred; total, sixteen hundred. On a gravel road the pull, 147 lbs. per ton, will be 112 lbs. upon a level; to ascend a hill rising one in twelve, such as often occurs, 133 pounds additional pull, making a pull of 245 pounds, which the engines must be capable of exerting. Suppose that the boiler is large enough to take the carriage up such a hill at three miles per hour, it will run at the following rates upon a level, upon different roads: On gravel, cutting off at half stroke, 9 miles, on a Macadamized road, 17 miles; on planks, 27 miles, the consumption of fuel per hour being constant. Hence it appears that the same force of steam, or fuel, besides overcoming the friction and other resistances of the machinery, will work sixty per cent more effectively on planks than it will on Macadamized roads, and nearly three times as effectively as on gravel roads, so far as increase of speed is concerned. If, instead of increasing the speed, we increase the load, we may draw upon the Macadamized road, upon a level, an additional carriage weighing with its load twenty-one hundred pounds, and carrying nine passengers. Upon a plank-road we may draw six additional carriages weighing with their loads sixteen hundred each, and carrying altogether forty passengers. Thus, as to the cost of the motive power to do the same work, it is more than three times greater on the gravel than on the Macadamized road, and eleven times greater on the plankroad; and on the Macadamized road it is three and a third times greater than on planks. These considerations show that it is not unreasonable to expect a profit upon plank-roads, even though it were certain that none could be made upon Macadamized roads. As to what may be done on common gravel roads, and others of a worse quality, it is only claimed that carriages may be run over them at a slow rate, with a large consumption of fuel. This has actually been done in England. So, if it be required that a carriage should deviate from the good road, for the sake of going to a place on a bad one, it can do so. In the foregoing estimates we have proceeded upon the supposition that the grades should correspond to the quality of the roads. This is true to a certain extent, the plank-roads being graded with great care; and on the prairies there are some which scarcely depart from a level; but in practice the loads would be lighter, and the speed greater, than we have assumed in the latter view: a compromise between the greatest speed and the greatest load, suited to the exigencies of business, would be made in each case. We have also supposed that the cut-off would be at half-stroke. This is in accordance with the views of several eminent engineers, who are extremely fond of simplicity, even in the light and subsidiary parts of machinery; and if the work were upon level grades, with resistances varying but slightly, there might be no sufficient reason to pay the first cost, and perhaps the cost of repairing of a complex apparatus for varying the cut-off. But as the total resistance, including the back-pressure in the cylinders, the friction, etc., will be ordinarily not more than a fifth of what the engines must be able to overcome, in order to get over hills on bad roads, we think that, upon mature consideration, the variable cut-off will be regarded as indispensable, where speed is required. The following comparison will show the advantage of it: The power necessary to run on a level, on gravel, is 52 of what is required to ascend such a hill as we have described. By reference to tables of expansion we find that, the pressure remaining constant, we may cut off at a fifth, and have sufficient power to overcome the resistance. Hence we may run fifteen miles per hour, on a level, with a boiler that will go up hill* only at three miles, when working at full stroke; and we have before stated that when cutting off at onehalf, we can run but nine and three-quarters. On a Macadamized road the power required is only 3 of what is required to ascend a gravel hill. By reference to tables we find that cutting off at oneeighth will give 399 of the force of a full cylinder. Hence we may run twenty-four miles per hour, and yet diminish the pressure considerably. But when cutting off at half we can run only seventeen miles, at the same cost. On planks the resistance is less than a fifth; and cutting off at a tenth will give nearly a third as much power as the full stroke: hence we may run, if required, nearly fifty miles per * By hill is to be understood a rise of 1 in 12, or 440 feet per mile. |