MISCELLANEOUS PAPERS. 



TUKXPIKING AND UNDERDRAINING COMMON EOADS. 



BY R. C. CARPENTER, C. E., MICH. STATE AGRICULTURAL COLLEGE. 



In this article it is proposed to briefly discuss the various methods of providing 

 an escape of the surplus water from roads. The methods recommended here are 

 valuable only when applied as here designated. It is not claimed that the removal 

 of the water will, in all circumstances and under all conditions, render a road 

 good ; but it is claimed that this is an essential condition to the making of a 

 good road, and one which if not provided by nature must be provided artificially. 



The systems of turnpiking and underdraining are fully considered, but met- 

 alling, that is applying a road covering, as gravel or broken stone, though 

 strongly recommended, is not treated of in this article. 



IMPORTANCE OF ROAD DRAINAGE. 



The principal cause of poor roads on all heavy soils is an over-abundance of 

 Avater, which renders the road wet, soft, and at times totally unfit for travel; 

 consequently we find that the road makers in all ages have strongly urged the 

 adoption of some efficient method of removing the surplus water. For instance, 

 McAdam, in his report to the British Board of Agriculture (Vol. VI., p. 46) 

 says, "Eoads can never be rendered perfectly secure until the following princi- 

 ples be fully understood, admitted, and acted upon, namely : that it is the 

 native soil which really supports the weight of traffic ; that while it is preserved 

 in a dry state it will carry any weight without sinking, and that it doss, in fact, 

 carry the road and carriages also ; that this native soil must previously he made 

 quite dry, and a covering impenetrable to rain must then be placed over it, to 

 preserve it in that dry state ; that the thickness of a road should only be regu- 

 lated by the quantity of material necessary to form such impervious covering, 

 and never by any reference to its own power of carrying weight. There are some 

 exceptions to this rule. A road of good naturally binding gravel may be laid 

 on a sub-bed of bog earth, which from its tenacity will carry all kinds of car- 

 riages for many years. 



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DIRECTIONS FOR PREPARING MACADAMIZED ROAD. 



Mr. McAdam in describing the method of preparing a road-bed says : "The 

 first operation in making a road should be the reverse of digging a trench. The 

 road should not be sunk below, but rather raised above the ordinary level of 

 the adjacent ground ; care should be taken at any rate that there be a sufficient 

 fall to take off the water, so that it should always be some inches below the level 



