. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. 1.â To mark out a curve of a certain given radius. Let AB be the straight line of a railway, B the point where the curve is intended to commence. BC, 1) C, &c radii of the curve to be described, Dd the deviation from the straight line at the end of any convenient length Bd, then C d'^ or (CD-fDrf)= = CB»+B(^ or VT) + T)d = x/C B' -\- a a-' Bd = \/C B= -|-~Erf= â C B, produce BD to e, making De = Brf, and draw TBt a tangent to the curve at the point D, tlien the tria
. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. 1.â To mark out a curve of a certain given radius. Let AB be the straight line of a railway, B the point where the curve is intended to commence. BC, 1) C, &c radii of the curve to be described, Dd the deviation from the straight line at the end of any convenient length Bd, then C d'^ or (CD-fDrf)= = CB»+B(^ or VT) + T)d = x/C B' -\- a a-' Bd = \/C B= -|-~Erf= â C B, produce BD to e, making De = Brf, and draw TBt a tangent to the curve at the point D, tlien the triangle TDB will be = and similar to the triangle DBrf, and the anjile TDB is = the angle eBl being vertical; also T D ^ / D and C B, C I), &c., being very great in comparison with BD, D E, &e., the triangles BlE, Del may he con- sidered practically equal and similar, and therefore E< = /e = Drfor Ec ^ 2D(/, which may be found by the above formula, where CB is the radius of the proposed curve, and Bd, any convenient length between the several points B, D, E, &c., is to be found. The rule iu words at length may be expressed as follows :âAdd together the square of the radius and the square of the distance apart of the points to be found in the proposed curve ; take the square root of their sum, and take from it t .eir radius: the result will be the amount of deviation from the straight line in the given lengthâ» hieh will give the first point of the curve; after which the deviations must be doubled, to render the curve uniform. 2 â To change from a greater to a smaller radius, or vice versa. Suppose at the point F the curve changes its radius, having now the shorter radius FG, it is evident the curves BDEF and FHI, should have a common tangent at F, which tangent may be found (on the ground) by taking E< = J Ee, and <F will be thecommon tangent, then the direction of the tangent IVh being found, the amount of deviation (AH) for the length F/i and radiu
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