54. AQUA REGIA: (Latin) _royal water_. A chemical compound so called from its power of dissolving gold. REGULUS OF COBALT: early chemical term referring to the metallic mass of an ore. 55. CAPTAIN KIDD: William Kidd, about whose early life nothing is positively known, was commissioned by the Governor of Massachusetts Bay Colony in 1695 to put down piracy. With a good ship under him, however, he himself turned pirate. On his return he was arrested, sent to England, tried, and executed in London in 1701. Some of his buried treasure was recovered by the colonial authorities in 1699. 58. GOLCONDA: a place near Hyderabad, India, noted for its diamonds. CRYPTOGRAPHS: from two Greek words meaning _hidden_ and _write_. The commoner term is "cryptogram." 59. SPANISH MAIN: the ocean near the coast of South America and the adjacent parts of the Caribbean Sea over which the Spaniards exercised power. 67. INSIGNIUM: (Latin) _a sign_. NOTES TO "THE PURLOINED LETTER" This detective story was published in "The Gift" for 1845. PAGE 69. NIL SAPIENTIÆ, etc.: (Latin) _Nothing is more hateful to wisdom than too great acuteness_. C. AUGUSTE DUPIN: clever amateur who solves the mysteries which baffle the police. Most writers of detective stories follow this example set by Poe. AU TROISIÈME: (French) _on the third floor_. FAUBOURG: (French) section of a city. SAINT GERMAIN: a section of Paris on the south bank of the Seine, once the abode of the French nobility. AFFAIR OF THE RUE MORGUE: a reference to the detective story, "The Murders in the Rue Morgue." THE MURDER OF MARIE ROGÊT: a reference to another detective story, "THE MYSTERY OF MARIE ROGÊT." The writer is playing the same part as does Dr. Watson in the various Sherlock Holmes stories by Conan Doyle. PREFECT: (French) _chief_. 71. CANT OF DIPLOMACY: set phrases used in intercourse between representatives of governments by which they hint at their meaning. 73. HÔTEL: (French) _residence_. AU FAIT: (French) _expert_. 76. MICROSCOPE: since Poe's time the microscope is, in stories, almost an invariable part of a detective's outfit. 79. ABERNETHY: John Abernethy (1764-1831). A celebrated London physician. 80. ESCRITOIRE: "A piece of furniture with conveniences for writing, as an opening top or falling front panel, places for inkstand, pens, and stationery, etc."--_Century Dictionary_. PROCRUSTEAN BED: In Greek mythology, Procrustes (derivatively "the stretcher") was a giant who tied those whom he caught on a bed, making them fit by stretching them out if too short, and by cutting off their limbs if too long.