No. 7: Aviation

The Aviation takes its name from the sky blue tinge derived from Creme de Violette, a liqueur that was apparently at one time almost impossible to find. Consequently, the titular ingredient was actually left out of many recipes, including the recipe in the influential 1930 Savoy Cocktail Book.

Luckily for us, Rothman & Winter is producing a Creme de Violette that is now available in the US (this is the brand that Anvil uses), which means that we can enjoy the Aviation in its original incarnation. Originally published in Hugo Ensslin's 1916 "Recipes for Mixed Drinks," the Aviation also calls for dry gin as its base, fresh lemon juice, and Maraschino liqueur:

Aviation Cocktail (Original Recipe)

1/3 Lemon Juice
2/3 El Bart Gin (no longer available; substitute another dry gin)
2 Dashes Maraschino
2 Dashes Creme de Violette
Shake well in a mixing glass with cracked ice, strain and serve.

The Aviation is one the drinks that I will happily reorder once, you know, I'm finished trying all 99 other cocktails on the list.

(Sources: Food&Spirits and Cocktail Hacker)