Contents page changes made to agree with chapter headings: "Lost—$100,000!"—quotes and exclamation point added. "The Double Code"—quotes added. "Thirty Thousand," and again on P. 253—hyphen removed (more frequent without).
After Contents page, "On Secret Service" displays twice—once alone on a page, and again above the Chapter I heading. One of the redundancies has been deleted.
Missing or incorrect punctuation repaired.
Spelling errors fixed.
Hyphenation variants changed to most frequently used version.
P. 54 "Simpson lives" original reads "Simpson lived."
P. 58 Thought break added for consistency.
P. 89 "Douglass" changed to more frequently used "Douglas."
P. 177 Code table: Original shows first number under q as "19." Corrected to "17."
P. 198 "well dressed" changed to "well-dressed."