[21]. Fig. [34].

[22]. Fig. [34].

[23]. Fig. [37].

[24]. Figs. 38 and 39.

[25]. Fig. [36].

[26]. See Fig. [36], and remarks thereon.

[27]. Fig. [41].

[28]. Fig. [42].

[29]. See Fig. [29].

[30]. See Chapter V.