Changes to the text have been limited to typographical errors. These are listed below with other observations:
Page 5, "47" changed to "49" (in Table of Contents: Chapter IV ... page 49.)
Page 5, "77" changed to "75" (in Table of Contents: Chapter VI ... page 75.)
Page 5, an Appendix starting on p. 122 is not listed in the Table of Contents.
Page 32, Figure 69 originally on page 32 moved to page 33; appears as illustration for HTML version and is transcribed as text for this Plain Text version.
Page 33, note hand-written correction to the poster (Figure 69) "stamps" should read "letters" (unpaid and unfranked letters will also run the risk of misdelivery.)
Page 36, missing closing parenthesis added "(Fig. 77)".
Page 45, there is no Figure 123.
Page 45, "129" changed to "128" ("Figs. 126-128".)
Pages 57 & 58, duplicate use of figure numbers 167 and 168.