As we observe, this drink was created at the Pendennis Club in Louisville, now more than 100 years ago. It's a simple combination of some sugar, bitters, and whiskey (usually bourbon), with some soda added, if desired. By way of comparison, here's a recipe from Old Crow:
So, the amount of sugar and bitters -- and even the whiskey -- can vary, according to taste. Some recipes omit the soda and add water instead, as we see in the following recipe from Fleishmanns:
So, the precise combination of water, soda, bitters, sugar, and whiskey isn't precise. Basically, whiskey, with a little flavor from bitters and a little sweet, and some sparkle from the soda if you're in the mood. A man's drink. However, maybe you're picking up on the baroque garnishments that accompany this otherwise simple drink. There's practically a Carmen Miranda fruit basket hat in this drink! Lemons, oranges, pineapples, cherries -- no worry about getting your daily vitamins with this one.