Course of Military Instruction Orginally Composed for the Use of the Royal Engineer Department PDF Download

Author: Sir Charles William Pasley
Publisher: Rarebooksclub.com
ISBN: 9781230071664
Category :
Languages : en
Pages : 68

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Book Description
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1814 edition. Excerpt: ...it has been judged convenient, to make the proportion between the span and rise of the arch, different from that which the transverse axis and the semi-conjugate bear to each other, in the last problem. Consequently, although the figures in both are drawn exactly by the same rule, . the curve of the arch in this problem is not equal and similar to the halt' oval of the former problem; which would have been the ease, if the above-mentioned proportions had been equal. Rub out the perpendicular, the bisecting line, and that oblique line, ' which was drawn from the top of the rise of your arch. From your lower center, with a radius /" extending as far as the top of the rise of your arch, describe an arc; which must be bounded by the two oblique lines that were drawn from the same point. From the right and left centers, with a radius extending from each as far as the nearest extremity of the span, describe arcs outwards, each of which must be bounded by one of the L oblique lines on one side, and by the nearest extremity of the span, on the other. If the former part of your operations has been performed accurately, the three arcs which you have just described, will coincide; in such a manner as to form one continued curve, resembling the semicircumference of an ellipse. This curve will represent the outline of your required compound Dot the rise of your arch; and rub out the produced part of the same line, You must next consider what will be the most convenient dimensions for your arch stones; after which you will divide your curve accordingly. Let us suppose that our present arch izather a small one, so that nine arch stones would be enough for the upper segment of it; you will, therefore, divide the arc of your upper...