Elements of Surveying, and Navigation: With Descriptions of the Instruments and the Necessary Tables |
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Page 70
... telescope MN . This telescope is connected with a hollow cylinder , which is worked freely round the outer spindle , by the thumb- screw P having a pinion working into a concealed cog- wheel , that is permanently fastened to the limb of ...
... telescope MN . This telescope is connected with a hollow cylinder , which is worked freely round the outer spindle , by the thumb- screw P having a pinion working into a concealed cog- wheel , that is permanently fastened to the limb of ...
Page 71
... telescope , with its attached level , rests on the vernier plate , to which it is made fast by three adjusting screws , placed at the angu lar points of an equilateral triangle . The vertical semi- circle UV , is called the vertical ...
... telescope , with its attached level , rests on the vernier plate , to which it is made fast by three adjusting screws , placed at the angu lar points of an equilateral triangle . The vertical semi- circle UV , is called the vertical ...
Page 72
... telescope , and at the focus of the eye - glass . The vertical hair is moved by two small hori- zontal screws , one ... telescope . Having screwed the tripod to the instrument , extend the legs , and place them firmly . Then loosen the ...
... telescope , and at the focus of the eye - glass . The vertical hair is moved by two small hori- zontal screws , one ... telescope . Having screwed the tripod to the instrument , extend the legs , and place them firmly . Then loosen the ...
Page 73
... telescope in the Y's , and make the same correction again ; and so on , until the bubble stands in the middle of the tube , in both positions of the tele- scope : the axis of the level is then horizontal . Let the telescope be now ...
... telescope in the Y's , and make the same correction again ; and so on , until the bubble stands in the middle of the tube , in both positions of the tele- scope : the axis of the level is then horizontal . Let the telescope be now ...
Page 74
... telescope comes directly over two of the levelling screws , then turn them contrary ways , till the upper telescope is horizontal ; after which , turn the vernier plate 180 ° , and if the bubble of the level remains in the middle of the ...
... telescope comes directly over two of the levelling screws , then turn them contrary ways , till the upper telescope is horizontal ; after which , turn the vernier plate 180 ° , and if the bubble of the level remains in the middle of the ...
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Common terms and phrases
axis back-sight base line bearing called centre column comp Cosine Cosine D Cotang course decimal degrees determined difference of level direction divided double meridian distance draw east error example feet figure fore-sight given angle given line given point ground half hence horizontal angle horizontal distance horizontal line horizontal plane hypothenuse inch instrument intersection latitude and departure length line of collimation logarithm marked measure method miles multiplied natural sines needle parallel passing perpendicular plane of reference Plane Sail plane triangle protractor quotient radius right angles right-angled triangle rods scale of equal screws secant sector sides sights similar triangles spherical excess spider's lines square chains staff station straight line subtract surface survey Tang tangent telescope theodolite trigonometrical variation vernier plate vertical limb yards
Popular passages
Page 10 - The logarithm of . the quotient of two numbers, is equal to the logarithm of the dividend diminished by the logarithm of the divisor.
Page 38 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees...
Page 45 - C' (89) (90) (91) (92) (93) 112. In any plane triangle, the sum of any two sides is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference.
Page 138 - ... the time of revolution is 23 h. and 56 min. To the eye of an observer, this star is continually in motion, 'and is due north but twice in 23 h. 56 min. ; and is then said to be on the meridian. Now, when it departs from the meridian, it apparently moves east or west, for 5 h. and 59 min., and then returns to the meridian again. When at its greatest distance from the meridian, east or west, it is said to be at its greatest eastern or western elongation.
Page 61 - Being on a horizontal plane, and wanting to ascertain the height of a tower, standing on the top of an inaccessible hill, there were measured, the angle of elevation of the top of the hill 40°, and of the top of the tower 51° ; then measuring in a direct line 180 feet farther from the hill, the angle of elevation of the top of the tower Cway 33° 45' ; required the height of the tower.
Page 9 - THE LOGARITHM: of a number is the exponent of the power to which it is necessary to raise a fixed number, to produce the given number.
Page 142 - Now, if the elongation, at the time of observation, was west, and the north end of the needle is on the west side of the line, the azimuth, plus the angle shown by the needle, is the true variation. But should the north end of the needle be found on the east side of the line, the elongation being west, the difference between the azimuth and the angle would show the variation, and the reverse when the elongation is east. 1. Elongation west, azimuth 2° 04' North end of the needle on the west, angle...
Page 39 - The secant of an arc is the line drawn from the centre of the circle through one extremity of the arc, and limited by the tangent passing through the other extremity. Thus, 00 is the secant of the arc AB.
Page 44 - CB : CA : : sin A : sin B. For, with A as a centre, and AD equal to the less side...
Page 22 - In a Right-angled Triangle, the side opposite the right angle is called the Hypothenuse ; and the other two sides are called the Legs, and sometimes the Base and Perpendicular.