A Treatise on Military Surveying: Including Sketching in the Field, Plan-drawing, Levelling, Military Reconnoissance, Also a Particular Description of the Surveying Instruments Commonly Employed by Military Men, with Instructions for Using and Adjusting ThemW.H. Allen, 1847 - 344 Seiten |
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Seite 5
... circle , thus , which denotes a station . Place the centre of the protractor at this point , and endeavour to make any one of the lines which are drawn across it , to coincide with one of those upon the paper , being careful to keep its ...
... circle , thus , which denotes a station . Place the centre of the protractor at this point , and endeavour to make any one of the lines which are drawn across it , to coincide with one of those upon the paper , being careful to keep its ...
Seite 6
... circle of 360 ° . Consequently , all bearings lying on the west side of the meridian , are read off from south to- wards the north ; and therefore in the present instance the bearing of D is 156 ° N. W .: that is , 156 ° from the south ...
... circle of 360 ° . Consequently , all bearings lying on the west side of the meridian , are read off from south to- wards the north ; and therefore in the present instance the bearing of D is 156 ° N. W .: that is , 156 ° from the south ...
Seite 13
... circle NES W ( plate IV . , fig . 1 ) represent the compass , having a line , HL , passing through its centre : the circle being divided into twice 180 ° , that is , the semi- circle NE S is numbered from 0 to 180 ° , beginning at N ...
... circle NES W ( plate IV . , fig . 1 ) represent the compass , having a line , HL , passing through its centre : the circle being divided into twice 180 ° , that is , the semi- circle NE S is numbered from 0 to 180 ° , beginning at N ...
Seite 21
... circle . A clamping screw , A , to prevent the horizontal circle from moving round . A tangent or micrometer screw , B , to turn the instrument slightly , after being clamped by the screw A. A screw , P , for fixing the upper or index ...
... circle . A clamping screw , A , to prevent the horizontal circle from moving round . A tangent or micrometer screw , B , to turn the instrument slightly , after being clamped by the screw A. A screw , P , for fixing the upper or index ...
Seite 22
... circle is truly level . The vertical arc is in a plane , perpendicular to the horizon . The line of sight , or of collimation ( i . e . , axis of the telescope ) , must be true , and the level at- tached to the telescope must be ...
... circle is truly level . The vertical arc is in a plane , perpendicular to the horizon . The line of sight , or of collimation ( i . e . , axis of the telescope ) , must be true , and the level at- tached to the telescope must be ...
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accuracy adjustment altitude artificial horizon ascertain barometer bearing bisect centre chain contour lines convenient correct cosine degrees depression direction distance divided divisions draw elevation equal error field-book fixed give given glass Greenwich ground half height hills Hindustani language horizontal circle inches instrument intersection Lachar latitude length limb longitude lunar distance Malaga mark means measured ment meridian meridian altitude method miles military sketching minutes moon mountain Nautical Almanac necessary needle object obtained off-sets operations paper parallax parallel parallel ruler perpendicular picket plane plate position protractor purpose reading reconnoissance refraction rhombus right angles rivers road Royal Engineers ruler scale screw sextant side sine slopes spirit-level square staff station sun's suppose surface survey surveyor taken tangent telescope theodolite tical tion triangle trigono trigonometrical Trigonometrical Survey true tube upper vane vernier yards zero
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Seite 195 - ... but it may be made in a variety of ways, so as to revolve on any light portable stand. The tube, when required for use, is filled with water (coloured with lake or indigo), till it nearly reaches to the necks of the bottles, which are then corked for the convenience of carriage. On setting the stand tolerably level by the eye, these corks are both withdrawn, which must be done carefully and FRENCH REFLECTINQ-LEVEL.
Seite 171 - THE first adjustment is that of the line of collimation; that is, to make the intersection of the cross wires coincide with the axis of the cylindrical rings on which the telescope turns : it is known to be correct, when...
Seite 228 - SO'OO inches as the average height of the barometer at the level of the sea (which is however too much), the altitude of the upper station is at once obtained by inspection of Table I, correcting for temperature of the stratum of air traversed by table II.
Seite 270 - ... reading off the arc; and half the difference of these numbers is the index error; additive when the reading on the arc of excess is greater than that on the limb, and subtractive when the contrary is the case. EXAMPLE. .
Seite 173 - ... error must be corrected by turning the screw, B, and the other half by the two parallel plate-screws over which the telescope is placed. Next turn the telescope a quarter round, that it may lie over the other two screws, and make it level by moving them, and the adjustment will be complete. Before making observations with this instrument, the adjustments should be carefully examined and rectified, after which the screw B should never be touched ; the parallel plate-screws alone must be used for...
Seite 145 - ... without any regard to thickness. This area, or the content of the plane figure, is estimated by the number of little squares that may be contained in it; the side of those little measuring squares being an inch, a foot, a yard, or any other fixed quantity.
Seite 299 - What is the error of the best tables now in use ? hours, or one minute of space in two minutes of time. Therefore, if we make an error of one minute in observing the distance, we make an error of two minutes in time, or 30 miles of longitude at the equator. A single observation with the best...
Seite 147 - ... in chains and decimals. Therefore, after the content is found, it will be in square links ; then cut off five of the figures on the right hand for decimals, and the rest will be acres. These decimals are then multiplied by 4 for roods, and the decimals of these again by 40 for perches.
Seite 104 - ... the number of links to be deducted from each chain's length, in measuring up or down an inclined plane, to reduce it to the horizontal measure.