Harvard Fizz
1 1/2 ounces brandy
3/4 ounce sweet vermouth
1 dash orange bitters
2 ounces soda water
Garnish: Orange slice
Build in a highball glass (10 ounce) with ice and top with soda.
Source: "Modern American Drinks" by George J. Kappeler (1895)

The original version of this drink was known as the "Harvard Cocktail" from 1895, which had a slightly different recipe. This "Fizz" version of it evolved from that one and is served as a traditional "Fizz" instead of in a cocktail glass.

The original Harvard Cocktail recipe was:

"One dash gum-syrup, three dashes Angostura bitters, half-jigger Italian vermouth, half-jigger brandy in half a mixing-glass of fine ice. Mix, strain into cocktail-glass, fill up with seltzer."