## A TREATISE ON THE PRINCIPLES AND PRACTICE OF LEVELLING |

### From inside the book

Results 1-5 of 18

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**diagram**let the straight line A B repre- sent the surface of the earth , upon the supposition of its being an extended plane , the direction of gravity at the points A , I , and B , would be represented by the lines A C , I D , and B E ... Page 8

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**diagram**for the tangent I H , r for the radius C I of the earth , and x for G H , the excess of the secant of the arc of distance above the radius I H being considered as equal to I G ; then ; 2 ( r + x ) 2 = r2 + 8 A TREATISE. Page 20

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**diagram**at page 26 , which represents the staff e as it appears in the field of the telescope , which shows objects inverted . If the staff be held perpen- dicularly , it will appear between and equally distant from each of the two ... Page 24

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**diagram**, let A B represent the section of a A D B lens ( or object glass of a telescope ) ; let the parallel lines on the left represent the rays of light coming from some distant object in that direction ; the instant they impinge ... Page 25

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**diagram**to re- present a section of it ; the image of a levelling staff held at a distance , in the direction of C , would be formed at the point W , the focus of the object glass ; let D F represent the eye - glass , which is fixed in ...### Other editions - View all

### Common terms and phrases

50 base adjustment approximate point b₁ b₂ back sight back staff bench mark calculations centre line centre stake chain clinometer Cloth 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 Dumpy Level earth edition engraving equal example field-book Folkstone Foot of bank Fore Sight forward reading forward station give gradient ground Gunter's chain horizontal line hypothenuse Hypsometry Illustrated inches inclined plane instrument J. P. WHITNEY length line A B lines of railway mean height measured Merrimack River method middle area mile object glass observer obtain outer rail parallax perpendicular placed plates point a₁ point H practice radius ratio Reduced Levels refraction represent right angles slope spirit-level stones subtracted superelevation surveyor Tables tangent telescope theodolite tion Top of bank Treatise turnpike road yards

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