Jack's Manual by J. A. Grohusko (1910, p.32)

0.5 portionIrish whiskey — Source gives 50% Irish whiskey.base
0.5 portionItalian vermouth — Source gives 50% Italian vermouth.modifier
ice — broken iceother
  1. Fill the glass with broken ice and add the Irish whiskey and Italian vermouth.
  2. Stir, strain, and serve.

Ice: Broken ice

See also: Manhattan Cocktail, Irish Cocktail