Scrape the finger-nail and the thumb-nail along a hair, and if, by the third time, it curls up, the owner is high-tempered.
Boston, Mass.

Scrape the finger-nail and the thumb-nail along a hair, and if, by the third time, it curls up, the owner is high-tempered.
Source: Current Superstitions (1896), entry 136.
Fanny D. Bergen, editor.
Modern normalized navigation; the historical attribution above remains unchanged.