A Manual of the Principles and Practice of Road-Making; Comprising the Location, Construction, and Improvement of Roads (Common, MacAdam, Paved, Plank, Etc.) and Rail-Roads (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1849 edition. Excerpt: ...roads rough and rulty, the admission of water being the great evil. He adds that nothing must be laid on the clean stone under the pretence of "binding;" for clean broken stone will combine by its own angles into a smooth solid surface, which cannot be affected by vicissitudes of weather, nor displaced by the action of wheels. The French engineers consider this cleanliness as unnecessary, since the travelling on the road very soon pulverizes the materials, and fills the interstices with dust and mud; though it might be replied that this took place only on the surface. Some of them, observing the large amount of vacant space in a mass of broken stone, have even proposed to combine with it in advance a certain proportion of calcareous stone, f or even clay and sand.J just sufficient to fill up the existing vacancies. This would doubtless make a road tolerably fit for use much sooner than the regular plan, but its permeability to water would entail on it all the evils mentioned in the preceding paragraph. A cubic metre of broken stones, placed in a water-tight box, which they just fill, can receive in the empty spaces between the fragments a volume of water r= yVs)or nearly one-half of the whole, the actual solidity of the stones being therefore only This does not vary for stones from 1 to 8 inches in size. After prolonged travel it increases to Ty, leaving a void of only Y For rolled pebbles and sand the actual solidity may be as much as T6. For perfect spheres, calculation shows that the solidity of a mass of them increases as their diameter decreases. Thus, if a cubic metre be filled with spheres 4 inches in diameter, their solid volume will be T6j; if they are 1 inch in diameter their volume is;and if only Jj inch, it...