To Change Dirt Road To Macadam

The modern system' of making roads ís a compcund of two systems, used in England in the early part of the century by 'JVlford and Macadam respectively. Telford was an enginecr and Macadam a road maker. The latter undoubtedly originated the principie of using small fragment8 of 6tone for roadw a y s . Telford insisted upon a stone foundation coinposed of regular stone froiu six to eight inches in size as base, to prevent the smaller stone (rom heilig pushed into tlie ground in soft places, and to insure good drainage. Macadam denied the usefulness of the foundation, and engineers are vet divided on tlic question. Macadam'a rule for the size of the fragments, termed road metal, vas six ouncos in weight. A cube ri one and onc-half inclies of compact limestone weigha about six ounces. Roadwaya with the macadam top and with or without the ïelford baso luay be ccinstructed from a common dirt road. The tnethod f or such work is described in a recent article in The Philadelphia Record. A variety of macadam roads are now under way in the vicinity of Philadelphia, and this article evidently treats the mal ter from a practical point of view: "In building a macadamizod road from a common dirt road it is es.sential tliat the surface should be scraped or excavated in order to gi re a good foundation for the layer of brokcn stone. The carth ís tlien thoroughly rollod, in order to compact it and prevent the broken stone from sinking too deeply in the soft earth. IftheTelford foundation is used thestones. which aro from SL3C to eight iuches in size, are set in position on the rolled earth and covercd with a six-inch layerof macadam metal, broken so as to pass through a two and one-half inch ring. ïhis is then rolled with a steain roller, the pattern most commonly used beingal5-ton machino, retina S-,,000. tbough 20-ton and 30-ton machines are in use. "When it is found that the metal will not yield to the roller the bed is ready for another layer of stone, whieh should be six inchcs deep in the center, sloping to thesides, and again compact ly rolled. A top dressing of fine broken stone, usually the screenings f rom a crusher, and not excecding three-quarters of an inch in largest dimensions, is spread over the road to a depth of two inches. A 6team roller will compact these screenings to a sniooth surface and the road is ready for travel. The rolling is facilitated and greater compactness secured if the stone is thoroughly sprinkled. Unless a great volume of trafüc is to pass over the road it is not necessary to have the metal a foot thick, a depth of eight inchea being suilicient for ordinary travel." In using the macadam on a common dirt road, without tho Telford foundation, the metal is placed upon the hard rolled surface in a uniform layer not esceeding 6 inches in depth. This layer is compactly rolled, and then another layer of metal is spread on and treated in tho same way, and so on until the roadway is completed according to The Records description of the Telford road. The great expenso of macadam roads is an obstacle to their general adoption. A method for reducing the expense is sugge8ted by Tho New York Journal of Couimerco in au editorial given below: "It would pay every where to construct the best macadamized roads, and the work should bo undertaken by the state where long thoroughfares are rnquired. Wo havo often suggested that it need cost very little if the convicta and crimináis who cannot bo given thcir liberty because of their unrestrained depravity wero cniployed at the task. This would effect a doublé object. It would build splendid roads at small cost throughout the length and breadth of the land, and it would tond to restrain crime. It is little hardship to the burglar or thehighwaymah lo keep hini in a prison where In' is will forl and clothed and better cared for on the whole than the average of honcst laborers who support thetnselves. If ho was set to breaking stone and road building in a chaiu gang, and made to eat his bread in the sweat of hia face, iindor a burning July sun or in tho chili of winler, lie would not think that conviction of crime was such a light matter."