# A Manual of Topographical Drawing

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Page 107 - The angle which a line makes with a plane is the angle which it makes with its projection on the plane.
Page 103 - D (Fig. 56) be the given square. It is required to construct a square which shall be to ABCD as 2 is to 5. Upon the side AB as a diameter, describe the semicircle AGB, and divide the line AB into five equal parts. At the second point of division, erect the perpendicular FG, and join A G.
Page 103 - Draw BH, and it will be the side of a square equal to one-half of ABC D. Lay off FB, equal to one-fourth of AB, and erect the perpendicular FI, then upon IB will be equal to one-fourth of AB C D.
Page 63 - ... upon the principle of vertical illumination, in which the maximum light is reflected upwards to the eye by a horizontal surface, and a minimum by a surface inclined 45° to the horizon. The latter, being the steepest slope at which earth will stand, is taken as the limit of least illumination.
Page 109 - V at r' ; hence tTr' is the required plane, Art. (32). Let the problem be constructed when one of the given lines is parallel to the ground line. Let the problem, to pass a plane through a given point parallel to a given plane, also be constructed. 48. PROBLEM 12. To pass a plane through a given right line, parallel to another right line.
Page 89 - The title. This may be placed outside the border, if it takes up only one line ; but if it requires several, then it must be placed within it. The letters composing the name of the locality...
Page 103 - CD (Fig. 16) be the given square, and let it be required to construct a square that shall contain 2, 3, 4, &c., times its surface.
Page 87 - II, measured across the middle, or exclusive of the caps, as the unit, the widths of the other letters, or of their characteristic parts, may be expressed approximately by the numbers in the third column of the table. In case of letters having oblique lines, these widths are to be taken at the intersections of the outer oblique lines with the upper or lower limit of each letter. The caps are in all cases excluded.