## The Practice of Engineering Field Work, Applied to Land, Hydrographic, and Hyraulic Surveying and Levelling, for Railways, Canals, Harbours, Towns' Water Supply ... Including the Description and Use of Surveying and Levelling Instruments and the Practical Application of Trigonometrical Tables |

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**equal to two right angles , these two straight lines shall be in one and the same straight line**. The 15th , Book I. If two straight lines cut one another , the vertical or opposite angles shall be equal . The 17th , Book I. Any two ...### Common terms and phrases

adjustment ascertain backsight base beam compasses bearing Bristol Channel centre chain line chainage channel chords circle clamp coefficient coincide column compass correct cosecant cosine coversine curve diameter difference of level direction distance ditto ditto divided Dumpy Level English Channel equal exterior angle fall feet fences field-book figures fixed gauge give given glass ground Gunter's chain half height Holyhead horizontal inches instrument intersection Irish Sea Length of Arc limb manner mark means miles minutes moon multiplied object observations obtain offsets overfall parallax parallel perpendicular plotted portion position practice protractor radius reading right angles rise scale secant sextant side sight sine square staff staff-holder station straight line stream subtended subtract surface survey tables taken tangent tangent screw tangential angle telescope theodolite tidal tion traverse triangle velocity vernier plate versine vertical zero دو

### Popular passages

Page 43 - IF a straight line touch a circle, and from the point of contact a straight line be drawn at right angles to the touching line, the centre of the circle shall be in that line.

Page 50 - If, at a point in a straight line, two other straight lines, upon the opposite sides of it, make the adjacent angles together equal to two right angles, these two straight lines shall be in one and the same straight line.

Page 50 - If a side of any triangle be produced, the exterior angle is equal to the two interior and opposite angles ; and the three interior angles of every triangle are equal to two right angles.

Page 45 - ... subtending the obtuse angle, is greater than the squares of the sides containing the obtuse angle, by twice the rectangle contained by the side upon which, when produced, the perpendicular falls, and the straight line intercepted without the triangle between the perpendicular and the obtuse angle. Let ABC be an obtuse-angled triangle, having the obtuse angle ACB, and from the point A let AD be drawn perpendicular to BC produced.

Page 44 - If a straight line be divided into any two parts, four times the rectangle contained by the whole line, and one of the parts, together with the square of the other part, is equal to the square of the straight line which is made up of the whole and that part.

Page 44 - If there be two straight lines, one of which is divided into any number of parts, the rectangle contained by the two straight lines is equal to the rectangles contained by the undivided line, and the several parts of the divided line.

Page 62 - But this is no derogation to their truth and certainty, no more than it is to the truth or certainty of the three angles of a triangle being equal to two right ones; because it is not so evident, as "the whole is bigger than a part;" nor so apt to be assented to at first hearing.

Page 169 - TO THEIR DIFFERENCE ; So IS THE TANGENT OF HALF THE SUM OF THE OPPOSITE ANGLES', To THE TANGENT OF HALF THEIR DIFFERENCE.

Page 50 - The angles which one straight line makes with another upon one side of it, are either two right angles, or are together equal to two right angles.

Page 45 - Therefore, in obtuse-angled triangles, &c. QED PROP. XIII. THEOREM. In every triangle, the square of the side subtending either of the acute angles is less than the squares of the sides containing that angle, by twice the rectangle contained by either of...