New road covered with gravel, five inches thick....... Solid Road, with gravel.. Trucks of Diligences, small two tons. wheels, five tons, .... .1-12.................... Smooth and solid earth Road.........1-41. Dry and smooth Macadamised Road.1-75.........1-55...... Moist and dusty Road...... ..1-26 .1-48 ..1-69.........1-50.........1-44 ..1-98.........1-68..... ....1-64 From the diversity of opinion among writers as to the proper average estimate of the useful effect of a horse-by fixing the grade at one in twenty-one, and supposing the horse to be passing at the rate of two miles per hour, equal to a tractive force of one hundred and sixty-six pounds, by placing the resistance at 1-60 of the load, as the common average, we will find the ability of the horse to be 2,700 pounds, or 10,800 pounds, as the load of a fourhorse team. Desaquiliers fixes the power of a horse at two hundred pounds, with a speed of two and a half miles per hour; M. Sauver at one hundred and eighty-nine pounds, with a velocity of three miles per hour; Moore, an English writer, at eighty pounds, with a velocity of eight miles per hour-continued for ten hours. Tredgold's estimate is for six hours. 2 miles per hour, 3 miles per hour, 160 pounds. 4 miles per hour, 83 pounds. 125 do. 5 miles per hour, 43 2-3 do. Brown, the celebrated engineer, from experiments upon fiftytwo teams, or one hundred and forty-four horses, says: "The force exerted by each horse is one hundred and sixty-three pounds, at two and a half miles per hour. "As these experiments were fairly made, and by horses of the common breed used by farmers, these numbers may be considered a pretty accurate measure of the force actually exerted by horses at a plough, and which they are able to do without injury for many weeks." The same force required of a horse in ploughing, would, on a good Plank Road, with a grade of one in thirty, haul 3,260 pounds, and with one in twenty-one 2,505 pounds. Assuming, therefore, the resistance on a well laid Plank Road to be 1-98, we have then a good foundation for any estimates required. This is certainly a very favorable view of the subject, and may, when the road first comes into use, require some modification. Its best period, we think is, when the first surface of the plank has been used long enough to reduce every thing to the greatest degree of solidity and hardness. Softer wood increases the resistance, good yellow pine would, we think, offer a resistance of one in eighty, cypress one in seventy-three. On the maximum grade of one in twenty-one, which will, of course, determine the weight of the load, the resistance from gravity being in the proportion to the size of the angle of inclination, will be one-twentieth of the weight, to which the resistance from friction being added gives 94-1,400, or 643-10,000 of the load for the aggregate resistance in overcoming the ascent. Thus a weight of sixty-four pounds, suspended over a pulley, would drag 1,000 pounds fixed upon wheels up an ascent of 1 in 21, upon a Plank Road. We may assume that the resistance from friction on the macadamized road, compared with the Plank Road is as three to one, or one-tenth of the weight; that the rises, to which such roads have to be accommodated, are, at times one to eight, and we have one-tenth to one-eighth-eighteen-eightieths of the load for the general resistance. One thousand pounds, therefore to be drawn over such a road would require a weight of two hundred and twenty-five pounds suspended over a pulley. The advantages possessed, therefore, by the Plank Road over the other, would be as sixty-four pounds is to two hundred twenty-five. With a grade of one in twenty-one, six horses or mules could draw sixty barrels of flour or thirty bales of hemp or cotton, and by reducing the grade from one in twenty-one to one in thirty, six mules or horses would be able to draw seventy-four barrels of flour or thirty-seven bales of hemp. One thing should never be forgotten in laying out grades, namly: that it is advisable, and sometimes economy, to make a detour of considerable extent, or to cut through heavy work rather than attempt to carry a road over an ascent of any great extent, wherein the grade is under one in sixteen. Animals can, by extraordinary exertions, draw a load up an ascent with a grade of one to twelve, and even under; but is it not evident that it is an impossibility to convey a heavier load over the entire length of the road than can be dragged upon the steep ascents? Hence, the folly of pursuing a pernicious course in the first stage of operations on a Plank Road, seeing that an easy ascent permits the passage of much heavier loads than where the grade is unfavorable. Should a few thousand dollars more be expended upon a good grade, it will, in the end, prove the wisdom and propriety of such a course. DRAINAGE. After a good grade, the next question of moment is complete and THOROUGH DRAINAGE. However excellent the grade, and admirably well performed the work on a road may be, if the drainage is incomplete, much of the utility of the road is lost. We urge it as a subject of vital importance to drain well, whatever the cost may be. To effect this, let the ditches on either side of the road be at least three feet deep, and with true slopes. Outlets for the water should be provided wherever a convenient one can be found. Let those outlets have as much descent as possible. If the ditchings and outlets be efficient, the plank will last much longer, and the road be always in better condition. Where it is difficult on any particular side of the road to obtain an outlet, run a culvert under the road, if one can be found on the other side. The object, at all times, should be to carry off every drop of rain which may fall on the road. The centre of the road should be thrown up at least twenty-two inches. Throw away the sods; let no earth be used but what will afford a firm and solid foundation when it has settled. Let the right side of the road, coming into town, be selected as the side for planking.-The face of the road, between the ditches, should be twenty feet wide, eight feet for the plank and twelve feet for the earth track. When the road is evenly thrown up, let it then be rolled with a heavy roller. This can be made by taking a log three feet or so in thickness, cut it six or eight feet in length, peel the bark off, and make it tolerably round; then bore two holes, two inches in diameter, in the ends of the log, as near the centre as possible; hew out a pair of stout fils, make two pins of dog-wood, or of an equally hard wood, leaving heads to the pins, bore a hole in each of the fils and mortice a cross bar into the fils two feet from the holes, after driving the pins in the centre holes, a team may be attached to the fils, or what is better, saw them so as to leave them but three feet in length, and hitch your team to the middle of the cross bar. After a thorough rolling, if any place requires more earth, let it be supplied. If sleepers are used, let the trenches for them be four and a half feet apart, and the sleeper let in so as to allow the plank to touch the earth. A tendency is now manifested to set the use of sleepers aside entirely, for the reason that on solid ground they are of no use, if any fastening can be used to keep the planks in place without them; and in wet and mucky soils the sleepers commonly used are a positive injury, from the vibration caused by passing teams. This vibration causes a churning of the wet soil, which is soon washed away from under the sleeper, and causing a depression in the road. It is not depth of sleepers that is needed -it is width for "bearing." Sleepers have only been useful for keeping the road in shape while it was settling; they add at least $400 additional cost to the mile, without any adequate utility sufficient to warrant their use where they can be dispensed with. In wet or soft places, if the draining has been properly attended to, we would recommend the use of a cheap kind of boards, say winding edge boards from nine to fifteen inches wide and one to one and a half inches thick. We prefer those from the fact that they will never vibrate in the ground, and not having the depth to settle that a sleeper has, they therefore allow the planking at all times to lay firmly bedded in the soil. Eight feet has uniformly been deemed a sufficient width for roads in the eastern States. We think it a matter of doubt whether our heavy western and southern teams of six horses or mules. and frequently six yoke of cattle, will find this width a sufficient one, particularly when they have to get on the planking after having had to turn off. Nine feet might, we think, answer the purpose. From the prevalent opinion entertained by people at large, that no skill is required to construct plank roads, we anticipate much dissatisfaction in many sections from the ill-advised attempts of persons to construct such roads without a proper conception of their requirements. We are sorry to see a Senator in our Legislature, in a report. otherwise able, setting forth this idea. To secure a good road should be the aim of all interested, and the chief requisite in a Plank Road being a good and well drained foundation--every engineer should, therefore, feel the importance of this undertaking and endeavor to make his work a monument of skill and judgment, rather than a clumsy thing for sensible men to laugh at. It should be always understood that the loaded team keeps the road, and where two loaded teams meet, the team going out from town is the only one that can turn off the track. The planked part of a road should incline three inches in the entire width of the planking. No circumstances will justify laying a plank road in the centre of the road way-first, because in that event the plank would be level on the top. Whereas, it is of the utmost importance to have a slant to lead off the water-and secondly, in wet weather especially, the one wheel running off on the earth track, finds less resistance to cutting than the other, consequently, the weight of the load being thrown on that wheel, must necessarily increase the weight of the draft, and soon cause the earth track to rut up and need repairs. A double track is rarely required on any route. Actual experience has demonstrated that any arrangement in the building of a plank road, whereby the earth settles away from the plank, allowing confined air to exist underneath, is fatal to the durability of a road. If the plank is well bedded in the soil, the period at which we may safely set down the duration of a Plank Road is, if of pine or other soft timber, eight years; oak, it is thought, will last two or three years longer. The wear, by abrasion, is calculated at one-fourth of an inch yearly, and the plank will last till worn down to one and a quarter inches. The plan is adopted in many places, of turning the plank over, after two or three years wear. A slight covering of soil is useful on the planking, and effectually avoids the dangers suggested, of slipping of the animal. In speaking of single and double tracks, Mr. Geddes, the distinguished New York Engineer, observes: "Great speculative objection was made in the start to but one track; but we have the entire community with us, in deciding that, on all ordinary roads, one track is fully sufficient. The reason is this: the travel in wet weather is entirely on the plank, except the turning out of light teams; but they seek the plank again as soon as they get around the team met or overtaken, so that the turn-out track is not cut with any continuous lengthwise ruts, and perhaps the wheels of not one team in a hundred turn-outs will strike the exact curve of another; consequently in our experience, our turn out track being well graded, passing the water easily and rapidly from its surface, remains perfectly hard and smooth." In concluding, we think, that we have, in general terms, shown the advantages of Plank Roads, and believe that we have shown from reliable data: 1. That Plank Roads are more easily and cheaply constructed than Railroads. 2. That they are more easily kept in repair, are less perishable, and yield larger and more certain returns than Railroads to the stockholders. 3. That produce can be conveyed over them, at least twenty-five per cent. cheaper, and with no greater loss of time, than on a Railroad. 4. That they are better able to accommodate the country at large, because they can be carried to almost every man's door. 5. That from the material and power used, they are peculiarly adapted to our Western and Southern States. 6. That they create markets at home wherever they reach, adding wealth and population; and, generally, that they are better adapted to an agricultural country, from the fact that they can be constructed and kept in repair easily, and that farmers and planters can own and manage them so as to make the transient travel pay the expenses of carrying their own produce to market, and also to return a handsome dividend besides. Now, in view of these facts and suggestions, it must readily occur to every farmer, within a reasonable distance of the line of a Plank Road, that he can better afford to take stock in such a company than any other of our industrial classes, because he can more cheaply pay for his shares-by working them out on the road. Every head of a family, with his teams, scrapers, shovels, and other implements which are always at hand in the cultivation, &c., of his farm, could, during those leisure times which every one occasionally enjoys, work out from one to a dozen shares, according to his force and proximity to the road, without any serious diversion of his attention from his regular vocation, or perceptive detriment to his crops. In fine, to all classes of farmers, no scheme was ever devised that afforded so rich an assurance of immediate and positive benefits to them, as the construction of plank roads in the neighborhood of their farms. It is vitally important, also, to the business man in towns and cities; it effectually removes the embargo that frequently, for months, shuts out the country from the city by reason of bad roads. |