Page 12, footnote 3: Chapter IX. changed to Chapter X.
Page 35: on page 155 changed to on page 135
Page 36: on page 34 changed to on page 35
Page 53: The lagging plank may be ... changed to The lagging planks may be ...
Page 113: (1) changed to (I) (2×)
Page 117: ... and it in this clearing ... changed to ... and it is in this clearing ...
Page 130: as indicated by Fig. 58 changed to as indicated by Fig. 61
Page 136: as indicated in the Fig. 63 changed to as indicated in the Fig. 65
Page 146: as shown by Fig. 63 changed to as shown by Fig. 69
Page 149: underpining changed to underpinning