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.

NOTATION

33

73. If in the last case MPQ should be revolved into H, its
revolved position would be represented by mnpq,; if revolved into
V, its revolved position would be represented by mpqv.
74. A new ground line will be represented by either G,-L, or
G'-L', according as it lies in the original H or V.
75. The projections of given or required lines, if visible, will be
represented by full lines.
76. The projections of given or required lines, when invisible,
and the projections of all construction lines will be represented by
broken lines consisting of dashes about I inch in length and
separated by very small spaces, thus:
77. The traces of given or required planes, if visible, will be
represented by full lines.
78. The traces of given or required planes, when invisible, and
the traces of all construction planes will be represented by mixed
lines, thus:
79. Lines connecting the projections of a point, also the projections of the path in which a point moves, will be represented by
dotted lines, thus:
80. The planes H and V and all surfaces and solids used in the
construction of a problem will be regarded as transparent.
All surfaces and solids constituting given or required portions
of a problem will be regarded as opaque.