Jack's Manual by J. A. Grohusko (1910, p.73)

1 dashAmer Picon base
1 portionrye whiskey — Source gives 100% rye whiskey.base
ice — broken iceother
  1. Stir the Amer Picon, rye whiskey, and broken ice.
  2. Strain and serve.

Ice: Broken ice

Recipes for Mixed Drinks by Hugo R. Ensslin (1917, p.27) — Ensslin 1917

1 dashLemon juice (fresh) — Lemon Juiceacid
1 jiggerCanadian whisky — Canadian Club Whiskeybase
1 dashAngostura bitters — Angostura Bittersbitter
  1. Shake well in a mixing glass with cracked ice.
  2. Strain and serve.

Ice: Cracked ice

This matters because it preserves a very lean whiskey-citrus-bitter branch at a time when many named drinks were becoming richer or more vermouth-driven.

The formula is tiny but specific; a dash of citrus here changes the drink's family position materially.

See also: Whiskey Sour, Modern Cocktail