Coffin Arithmetic
The Fifth Robe

Six spare choir robes hang on the vestry rail for visiting singers, shortest first, and the fifth has a purple stain on its cuff. A robe is the best disguise in a church: on the loft stair, anyone in one looks like a chorister. Prudence has the tailor’s bill in her ledger, and Josiah has his tape. “Purely professional interest,” he says, and measures the rail.
Prudence’s ledger · the tailor’s bill
- The six robes took 309 inches of black serge between them, and nothing was wasted.
- Each robe on the rail is 3 inches longer than the one before it.
- A robe fits only a wearer exactly 14 inches taller than the robe is long. Anyone else trips over it or shows their ankles, and Sorrowby would talk.









