2 dash Yellow Chartreuse (1/2 oz)
2 dash Dry Vermouth (1/2 oz Noilly Prat)
1 dash Orange Bitters (Angostura Orange)
Stir with ice and strain into a cocktail glass.
Tuesday last week, I skimmed my copy of Pioneers of Mixing at Elite Bars: 1903-1933 looking for that evening's nightcap. When I spotted the Williams, it appeared like a 3-2-1 with Scotch in place of the rye. I interpreted the book's vague proportions to mean two thirds Scotch and one third a split of Yellow Chartreuse and dry vermouth which would make it a bit drier than the 3-2-1.