A Treatise on the Principles and Practice of Levelling, Showing Its Application to Purposes of Civil Engineering, Particularly in the Construction of Roads
J. Weale, 1856 - 214 pages
100 feet chord 20 feet 2nd edition adjustment ĘSCHYLUS angle a b c angle of deflection b₁ back sight back staff bench mark bound in embossed calculated centre stake chain clinometer computed half width correct Cosine Cotang cross wires curvature curve cuttings and embankments datum line deflection angle deflection distance difference of level direction Dover Castle Dumpy Level embankment embossed cloth equal error EURIPIDES example Folkstone Foot of bank Fore Sight forward reading forward station French Languages ground Gunter's chain half-morocco inches instrument IV.-NATURAL SINES John Macneill length line A B marbled edges measured method middle ordinate NATURAL SINES observer obtain parallax perpendicular placed Plate practice quantity RADIUS 1-continued reduced levels right angles road side SINES AND TANGENTS slope SOPHOCLES spirit-level starting point staves sub-chord subtracted superelevation surveyor Table Tang tangential angle tangential distance telescope theodolite Top of bank Treatise vols
Page 11 - A Treatise on the principal Mathematical Instruments employed in Surveying, Levelling, and Astronomy...
Page 95 - Well-made roads, formed of clean, hard, broken stone, placed on a solid foundation, are very little affected by changes of atmosphere ; weak roads, or those that are imperfectly formed of gravel, flint, or round pebbles, without a bottoming or foundation of stone pavement or concrete, are, on the contrary, much affected by changes of the weather. In the formation of such roads, and before they become bound or firm, a considerable portion of the subsoil mixes with the stone or gravel, in consequence...
Page 72 - The area of each end added to four times the middle area, and the sum multiplied by the length divided by 6, will give the solid content. If the measures used in the calculation are yards, the result will be the content in cubic yards ; but if they are feet, the result must be divided by 27, to obtain the corresponding number of yards. CALCULATION OF THE TRIANGULAR PORTION O.
Page 92 - ... one ; for it wears so rapidly that the crust of a road made with it always consists of a large portion of the earthy matter to which it is reduced. This prevents the gravel from becoming consolidated, and renders a road made with it extremely defective with respect to that perfect hardness which it ought to have.