To Q, B, from the fissure of the maxilla to the border of the lips (G. and B.);
To O, D, from the internal angle of the eye to the angle of the lower jaw, provided that the line C, D be in proportion (G. and B.).
Fig. 109.—The Same Design as that of [Fig. 108], on which we have indicated, by Similar Lines, the Principal Corresponding Measurements.
Half the length of the head, and the dimensions which equal it; distance which separate the nape from the internal angle of the eye, and the dimensions which equal it; distance which separates the internal angle of the eye from the border of the lips, and the dimensions which equal it.[64]
[64] It is thus that in our teaching, but by means of lines of different colours, we present the proportions reproduced in [Fig. 108]. Experience has demonstrated to us that this replacement of letters by conventional lines renders the proportions more easily appreciable, and that these lines, striking the eye more forcibly, then impress themselves better on the memory. [Fig. 111] bears the same relation to [Fig. 110].
Finally, very frequently to O, H, from the internal angle of the eye to the insertion of the throat into the maxillary trough (G. and B.).
An equality still more frequent is that which exists between the distances:
O, B, from the internal angle of the eye to the margin of the lips;