That the days of the barbarous cobble-stone pavements, and of all other roadways approximating to them in character, are numbered, must, we think, be evident to every careful observer. This is an age of progress, but it is an age which favors smooth and rapid progress, and is intolerant of jolting and jarring. It has sickened of the intolerable nuisance of stone blocks and cobbles, and now demands something that will exact less of man and beast and vehicle, and it will get what it wants by and by. The construction of good and durable roads is no easy problem, especially in a climate like ours, where giant frosts annually get under the surface and upheave it, unless some adequate means can be devised to prevent them. To dig down below the reach of frost, and carry up a solid structure to the surface as in a foundation for a building, would, of course, do away with this difficulty; but it introduces another, even worse—enormous expense. The problem may, perhaps, be stated as follows : Required to make a roadway impermeable to water (which alone renders the action of frost destructive to roads), and at the same time sufficiently thick and strong to withstand the heaviest traffic for a reasonable period of time; smooth on its upper surface, but not so hard as to fail to afford good footing for horses; and dieap. But cheapness does not by any means mean small outlay in the first instance. A road costing four dollars per square yard at first, and having the capability to endure for twelve years, is cheaper than one costing two dollars, and lasting only three year's. And a road that will transfer a great proportion of the wear and tear from beasts of burden and vehicles to itself, may wear out rapidly and still be a very cheap road. There are also some minor reqnisites for roads in cities, such as facility in getting up and repairing gas and water-pipes and sewers, which may not be disregarded. In no field of construction, perhaps, can mere theorizing ' be less relied upon than in the improvement of our roads, proverbially bad both in city and country. Everything proposed must be brought to the test of actual and prolonged experiment, before it can be pronounced either good or bad. Hence it is impossible at present to pronounce intelligently upon the merits of many new claimants upon public favor. And in the cases of many of those which have been lor some time under trial, it is equally difficult to decide, as the circumstances under which they were tested have been in many cases the worst possible, and in no manner of accordance with the intentions of their originators. Thus the American Builder informs us that " The manner in which the wooden pavements are being put down this season in Chicago is enough to make the dead inventor of the Nicolson pavement laugh in his coffin. Indeed it is a ghastly joke. To avoid paying an honest and just royalty, the city authorities are compelling the sorely taxed people to throw their money away." The Nicolson pavement, if not the most durable, is certainly tbfe most agreeable of roads, but we insist that in very few instances have its promoters been able to secure for it anything like a fair chance. Its durability depends upon the manner in which the work of laying is performed perhaps more than any other pavement possessing equal merit, and so long as the work is performed as the Builder states it is now being done in Chicago, there will not be lack of those who will saddle the shortcomings of contractors upon the character of the pavement. We are informed by one of the promoters of the Nicolson pavement, that an important improvement has been made in the method of constructing it. It originated with Mr. De Grolyer, of Chicago, we believe ftnd consists of replacing the wooden pickets hitherto used to separate rows of the blocks, with a layer of concrete rammed as hard as possible. This supports the blocks laterally in a much more efficient manner than was attainable by the old method, and greatly adds to the durability of the pavement. We believe that experiment will ultimately lead to the construction of concrete roads which will answer all the requisite conditions. In fact, some statements made in regard to the Scrimshaw pavement, if they are to be relied upon, would seem to give hope that this ultimatum has already been reached. We are informed that this pavement has been tried in Portland, Maine, on a piece of road exposed to very severe wear from heavy trucks used to carry large blocks of granite, and has stood the test of wear and weather for eight years. This pavement is now being put down on Bedford avenue, in Brooklyn, and also in Fifth avenue. New York. It consists, first, of a foundation of stone laid like the cobble or block pavements. The earth and sand being carefully swept from the interstices of these stones, a layer of gravel and asphalt mixed with coal ashes is spread over the surface, and the whole rolled down with heavy rollers. Successive coats of fine gravel, asphalt, and coal ashes complete the work. Each coat is heavily rolled down as applied; and the road when finished has an elegant appearance, and is delightful to drive over. The method of laying the concrete upon the old pavement without previously relaying it, is, we think, not likely to prove so efficient as when the stones are relaid, although on account of diminished expense it is done in some instances. Per contra, to the a-bove favorable statements in regard to the Scrimshaw pavement, we hear rumors of unsatisfactory results in Montague street, Brooklyn, where it has been recently laid, and some assert that no such results as the above, given on the authority of the committee, appointed to investigate the merits of the Scrimshaw pavement ,previous to its adoption in Bedford avenue, can be realized. Without crediting or discrediting the statements put forth in regard to this pavement, we shall patiently await the result of the experiments now in progress and, while we yet prefer tl*e Nicolson pavement when properly and honestly laid, to any road we have yet seen, that does not prevent us from hoping and expecting something which will prove an advance on anything yet devised for American roads.
This article was originally published with the title "Wood and Concrete Pavements" in Scientific American 21, 12, 185 (September 1869)