Gimlet

• 2 ounces gin
• 2 ounces bottled sweetened lime juice[?] (such as Rose's[?])
• 1 teaspoon sugar

Stir well with ice. Strain into pre-chilled cocktail glass. Sugar-frost rim of glass.

For the Vodka Gimlet, replace gin with vodka. As of the 1990s, maybe earlier, bartenders often answer requests for the gimlet with a vodka gimlet. They may also serve the gimlet on the rocks.

Surgeon Rear-Admiral Sir Thomas Desmond Gimlette (1857-1943) served in the Royal Navy during the time period when cocktails started to become popular. A naval medical officer would certainly have access to gin and lime juice. However, neither his obituary notice in The Times of October 6, 1943, nor his entry in Who Was Who[?], 1941-1950, mentions any inventiveness with regard to cocktails.

See also the Wikipedia Cocktail Guide.