Rum and Molasses

Daly's Bartenders' Encyclopedia by Tim Daly (1903, p.39)

1. Pour a small quantity of rum into a whiskey glass to cover the bottom and add a spoonful of black molasses.
2. Hand the bottle of rum to the customer to help himself.

Daly explicitly frames this as cold-and-grippe service, which makes it a useful restorative plain-drink witness.

The customer-finished service is the key part of the drink logic here.

The Reminder by Jacob A. Didier (1909, p.125) — Didier 1909

1. Place a spoonful of black molasses in a whiskey glass.
2. Hand the bottle of rum to the customer to help himself and serve with a spoon in the glass.

This matters because it preserves another plain-service, customer-choice branch that later cocktail histories usually ignore.

The service depends on the customer-finished pour rather than a fixed bartender-measured build.