Café Royal Cocktail Book by W. J. Tarling (1937, p.126)

0.67 partsweet vermouth — Martini sweet vermouthbase
0.33 partFernet Branca modifier
  1. Half fill the mixing tumbler with ice and stir until cold.
  2. Strain the chilled vermouth into a cocktail glass containing the Fernet Branca.

Ice: Ice in mixing tumbler

Described in the source as a good pick-me-up.