A Treatise on the Principles and Practice of Levelling: Showing Its Application to Purposes of Railway Engineering and the Construction of Roads, &cVan Nostrand, 1870 - 157 pages |
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Page 8
... equal to the excess of the secant of the arc of distance above the radius of the earth . The difference , G H , or M N ( see last figure ) , be- tween the true and apparent level may be thus found : put tin the adjoining diagram for the ...
... equal to the excess of the secant of the arc of distance above the radius of the earth . The difference , G H , or M N ( see last figure ) , be- tween the true and apparent level may be thus found : put tin the adjoining diagram for the ...
Page 9
... equal to the square of the distance ( 12 ) divided by the diameter of the earth ( 2 r ) , and con- sequently is always proportional to the square of the distance . The mean diameter of the earth is 7916 miles , and the excess of the ...
... equal to the square of the distance ( 12 ) divided by the diameter of the earth ( 2 r ) , and con- sequently is always proportional to the square of the distance . The mean diameter of the earth is 7916 miles , and the excess of the ...
Page 30
... equal to C E , therefore D and E are level points , being equidistant from the centre of the earth ; and if the reading of one staff above the ground is greater than the reading of the other , the difference will at once show the ...
... equal to C E , therefore D and E are level points , being equidistant from the centre of the earth ; and if the reading of one staff above the ground is greater than the reading of the other , the difference will at once show the ...
Page 34
... equal errors of an opposite kind may have been committed , when , the sum of each being of the same magnitude , a balance of errors would cause the extreme points to be right , whilst the inter- mediate levels would be incorrect ; but ...
... equal errors of an opposite kind may have been committed , when , the sum of each being of the same magnitude , a balance of errors would cause the extreme points to be right , whilst the inter- mediate levels would be incorrect ; but ...
Page 47
... equal distance from each staff ; but it is not essential that it be placed in the exact line between them , unless it should happen to prove the most ad- vantageous position . Plate II . represents an example of this kind of work , the ...
... equal distance from each staff ; but it is not essential that it be placed in the exact line between them , unless it should happen to prove the most ad- vantageous position . Plate II . represents an example of this kind of work , the ...
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Common terms and phrases
a₁ adjustment application approximate point b₁ back sight back staff bench mark Bridge calculations centre line centre stake chain Civil Engineer clinometer Cloth column computed half width construction correct cross wires curvature curve cuttings and embankments datum line depth of cutting determined diagram difference of level direction distance Dover Castle Drawing Dumpy Level earth edition engravings equal example feet Folkstone foot fore sight formula forward reading forward station give ground Guns Gunter's chain horizontal line hypothenuse Hypsometry Illustrated inches inclination inclined plane instrument Iron J. P. WHITNEY John Macneill length line A B lines of railway mean height measured method middle area miles object glass observation obtain parallax perpendicular placed quantity radius reduced levels represent result road side slope spirit-level Steam stones STRENGTH OF MATERIALS subtracted superelevation Survey surveyor Tables tangent telescope theodolite tion U. S. Navy Water wood-cuts
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