Elements of descriptive geometry, with applications to isometric projection and othe forms of one-plane projection; a text-book for colleges and ingineering schools by O. E. Randall.

INTERSECTION OF SURFACES BY PLANES

175

To find the points in which Jl-L intersects the meridian curve,
revolve the plane U about the axis A-B until it is parallel to V.
The vertical projection of the meridian curve will then be identical
with the vertical projection of the surface, and the vertical projection of M-L will fall at m'-l", Al remaining stationary. The points
n" and o", the points in which the line m'-l" crosses the vertical
projection of the meridian curve, are the vertical projections of

the revolved positions of the lowest and the highest points of the
required curve of intersection. The projections of N in true position will fall at n, and n', and the projections of 0 in true position
will fall at o, and o'.
A meridian plane TV, parallel to V, will cut from the surface a
meridian curve whose vertical projection is the vertical projection