. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. The principle of the above method is, that the curve is ranged by means of continual tangents; it would occupy too much space to de- scribe in detail the various methods of making the necessary calcu- lations, ;uid facilitating operations in the tield work, as well as the mode of finding the intermediate points, when it is required to put in a stake at the end of every chain, or half chain; these and many other points w ill readily suggest themselves to any person ; with niat
. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. The principle of the above method is, that the curve is ranged by means of continual tangents; it would occupy too much space to de- scribe in detail the various methods of making the necessary calcu- lations, ;uid facilitating operations in the tield work, as well as the mode of finding the intermediate points, when it is required to put in a stake at the end of every chain, or half chain; these and many other points w ill readily suggest themselves to any person ; with niatheniatical subjects. *'- c-o at all conversant The method which has been usually adoptetl for setting out curves is as follows. (See Figiu'e 1.) Let AB be the straight line, a tangent to the curve, B its termination, and C, U, E, &c., ecpiidistant points in the curve of given radius BO, O being its centre; produce AB to c, and draw Cc at right angles to Be; produce BC to (/, making Cd= CD=BC:, and join dV. Join OB, OC, OD. The angle rfCO=the angles BOG and CBO, (Euclid I. 3-2,) and the angle OCD=CBO .". the anfde dCD=the angle BOC=the angle COD, for BC=CD, by hyp. tlfen, by similar triangles COD, dCV; OC : CD : : CD ; dD= __. In order to obtain C the first point in the curve, calciJate BC the sine and cC, at right angles (by construction) to BC, the \'ersed sine of the ano-le BOC. If the chord BC is small in comjjarison w ith the radius Btf, Cc may be considered, at least for all practical pur- CD' poses, = half dD—i -^,^- , and Bc=BC. The above is a simple, and with proper care an accurate, method of ranging a curve where the groimd is clear from obstructions; it has beeu usual to take BC=one chain, but it is nuich better to take 2, 3 or 1 chains wdiere the nature of the ground will permit, as the errors arising from the diiHculty of setting up ranging rods and measuring offsets witli precision will be thereby nuuh diminished. Where the ground to be ranged over is n
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