The Buffet Blue Book by John H. Considine (1912, p.59)

lemonade — ordinary lemonadebase
Whiskey — Float on top.base
  1. Prepare an ordinary lemonade.
  2. Float whiskey on top, serve with a straw, and serve.

This entry is explicitly built from another house formula.

See also: Lemonade, John Collins

Source says to prepare an ordinary lemonade and float whiskey on top.