A Treatise on the Principles and Practice of Levelling, Showing Its Application to Purposes of Civil Engineering, Particularly in the Construction of RoadsJ. Weale, 1856 - 214 pages |
From inside the book
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Page
... contained in full in the valuable work of " Sir Henry Parnell on Roads . " An Appendix is added , with permission , containing a description of Macneill's instrument for the purpose of ascertaining the com- parative merits of roads ...
... contained in full in the valuable work of " Sir Henry Parnell on Roads . " An Appendix is added , with permission , containing a description of Macneill's instrument for the purpose of ascertaining the com- parative merits of roads ...
Page 43
... contain the readings of the two staves at the back and fore observations respectively . The difference of such readings is placed in one of the two side columns headed " Rise " or " Fall , " according as the ground at the forward ...
... contain the readings of the two staves at the back and fore observations respectively . The difference of such readings is placed in one of the two side columns headed " Rise " or " Fall , " according as the ground at the forward ...
Page 44
... contained in the columns of " Rise " and " Fall , " the former being considered as positive , and the latter as negative quantities ; thus , assuming the level of the starting point A as the datum , we have the first forward station ...
... contained in the columns of " Rise " and " Fall , " the former being considered as positive , and the latter as negative quantities ; thus , assuming the level of the starting point A as the datum , we have the first forward station ...
Page 80
... contain the numbers corresponding to a base of 50 , and a slope of 1 to 1 ( which is the slope of the cuttings in our example ) . But for a slope of 2 to 1 , reference must be had to the second series of the same Tables , which are ...
... contain the numbers corresponding to a base of 50 , and a slope of 1 to 1 ( which is the slope of the cuttings in our example ) . But for a slope of 2 to 1 , reference must be had to the second series of the same Tables , which are ...
Page 116
... contain the differences of level ( contained in columns 7 and 8 ) multiplied by the ratio of the slopes , and must have the same signs + or as the corresponding numbers in the preceding columns . - The last two columns contain the final ...
... contain the differences of level ( contained in columns 7 and 8 ) multiplied by the ratio of the slopes , and must have the same signs + or as the corresponding numbers in the preceding columns . - The last two columns contain the final ...
Common terms and phrases
100 feet chord 15 feet 20 feet adjustment ÆSCHYLUS angle of deflection approximate point b₁ b₂ back sight bench mark calculated centre line centre stake chain chords of 100 clinometer column computed half width correct Cosine Cotang cross drains curvature curve cuttings and embankments datum line deflection angle deflection distance difference of level direction embossed cloth equal error example feet radius Folkstone foot Fore Sight forward reading forward station give ground Gunter's chain inches inclined plane instrument IV.-NATURAL SINES John Macneill length line A B mean height measured method middle area middle ordinate multiplied NATURAL SINES observation obtain parallax perpendicular placed points a₁ practice quantity radii RADIUS 1-continued radius of curvature reduced levels right angles road SINES AND TANGENTS slope staves stones sub-chord sub-deflection subtracted superelevation surveyor Table Tabular Tang tangential angle tangential distance telescope theodolite Treatise vols yards
Popular passages
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.
Page 51 - ... reduced thereto), otherwise the section will be longer than it ought to be. For the purpose of assisting the surveyor in making the necessary reduction from the hypothenusal to the horizontal measure, when laying down...