Notes on Military Surveying and Reconnaissance |
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12 inches 12-inch scale 25 feet accuracy base breadth centre change of slope clinometer column of horizontal consequently constructed copying crest cubic datum line degrees of slope depth of shade diagram direction divided draughtsman drawn equal field-book field-sketching give given Gunter's chain height hills horizontal distance horizontal equivalents instrument interpolation intersection knoll known point laid length Longdown magnetic marked measured mile necessary number of degrees number of yards object observed angles off-sets orometer orthogonal pace paper parallel pencil perpendicular PLATE II PLATE VII point of triangulation position protract protractor re-entrants relative heights right angles road salient Sandhurst scale of shade Section 31 section 45 sextant shown side Sir James Ross sketch square station station-line strokes Superior slope surface survey surveyor table of gradients taken theodolite thickness tion traced triangles troops true north under-features upper edge vernier vernier scale vertical interval width
Popular passages
Page 55 - Multiply half the sum of the two parallel sides "by the perpendicular distance between them : the product will be the area.
Page 55 - To find the area of a triangle : — Multiply the' base by the perpendicular, and half the product will be the area.
Page 118 - К at object O (Fig. 3) through the plain part of the horizon-glass О. с The picket A will appear reflected in the silvered part of the glass; should it appear to the right of the object he must retire; if to the left, he must advance, until the picket A exactly coincides with (Гш.
Page 118 - If necessary, the right angle can be laid out to the right aud the rauge taken to the left, by reversing the operation herein detailed. some well-defined portion of the object. He then plants the picket С between his toes, and should verify the accuracy of the observation by resting his hand on the top of the picket and looking through the instrument again ; any slight error can then be rectified by forcing the head of the picket to or from him. No. 1 has thus planted the picket С at the right...
Page 55 - To find the area of a trapezium. Multiply the diagonal by half the sum of the two perpendiculars, falling upon it from the opposite angles, and the product will be the area.
Page 118 - CASE I. Where the base is between 60 and 120 yards. Suppose the distance from A to O (Fig. 3) to be required. At " Take the range," No. 2 plants a picket with square leather head and strut at A, the flat side of head turned to the left and the strut to the rear. No. 1 notices what portion of the object he can see from A, goes off about 100 yards to the left,* at about right angles to A O. He opens the instrument, pushes the arm HI against the stop K (by moving the button P), turns instrument upside...
Page 102 - ... whether it can be widened, or the obstacles removed which confine it. The ferries, bridges, fords, &c., met with upon the road, should be particularly described; the possibility of obstructing or breaking up the road, so as to prevent its being used by the enemy, or of destroying the bridges or fords upon it, should be stated. The...
Page 55 - To find the area of a parallelogram. Multiply the length by the height, or perpendicular breadth. Or, multiply the product of two contiguous sides by the natural sine of the included angle. To find the area of a triangle. Multiply the base by the perpendicular height, and take half the product.
Page 32 - ... and, setting one foot upon A, with this extent describe an arc cutting AB in B ; then, taking the extent of D° from the same line of chords, set it off from B to c ; and, joining A c, BA c is the angle required. Thus...
Page 118 - ... picket at C, lays one of the cross lines engraved on the head of the picket A on C, hooks his cord to A and stretches it to the rear in the direction given by the other line on the head of A, thus approximately setting oft