Van Nostrand's eclectic engineering magazine . 21) as a base and cut it byan inclined plane whose line of intersectionwith the plane of the base shall be parallelto A I, we will get an ellipse whose verticalaxis A P (Pig. 21) will = A I, and whosehorizontal axis C B will be greater than THEORY OF ARCHES. 105 C B. All lines parallel to AI will be un-changed in length, while all parallel to C Bwill be increased in the proportion of C B toC B. Now, by the principle of parallel pro-jections, the ellipse, which is the parallelprojection of the circle, will be balancedunder the forces which are the
Van Nostrand's eclectic engineering magazine . 21) as a base and cut it byan inclined plane whose line of intersectionwith the plane of the base shall be parallelto A I, we will get an ellipse whose verticalaxis A P (Pig. 21) will = A I, and whosehorizontal axis C B will be greater than THEORY OF ARCHES. 105 C B. All lines parallel to AI will be un-changed in length, while all parallel to C Bwill be increased in the proportion of C B toC B. Now, by the principle of parallel pro-jections, the ellipse, which is the parallelprojection of the circle, will be balancedunder the forces which are the parallel pro-jections of those under which the circle isbalanced. As we have seen, the circle is the curveassumed by the ring under a uniform hori-zontal and vertical force at each point of thesame kind, and equal in intensity ; for sucha system of forces is equivalent to a con-stant normal force around the curve. Forconvenience, these forces are represented inFig. (21) along the two diameters, eachlittle line representing the force on a unit. *M >:S
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Keywords: ., bookcentury1800, bookdecade1860, bookpubl, booksubjectengineering
