The Old Waldorf-Astoria Bar Book by Albert Stevens Crockett (1935, p.39)

0.33 partdry vermouth — French vermouthbase
0.33 partgin — Plymouth ginbase
1 dashAmer Picon — Amer Picon Bittersmodifier
0.33 partsweet vermouth — Italian vermouthmodifier
  1. Build the vermouths, gin, and Amer Picon bitters over ice.
  2. Serve in a cocktail glass.

See also: Bishop, Poker