Scale ca. 1:28,000. Two joined sheets. Relief shown by hachures. Depths shown by soundings. Based on Sayer & Bennett's "A Chart of the harbour of Boston, with the soundings, sailing-marks, and other directions," 1777; Le Rouge translated this chart's many notations into French. From the author's Pilote américain septentrional, 1778-79. v. 1. Published the year of the French alliance with America, this map provided the French navy with the best available charting of the preferred courses, depths and hazards of Boston harbor. A street plan for the city of Boston is provided, and the "ruines de Charles Town" is marked.