Of Smashes, Jerry Thomas writes "This drink is simply a julep on a small plan." (He has quite a lot to say about the julep, which I'll get around to soon.) Your spirit of choice, a little sugar, some water, a glass filed with shaved ice, and a garnish--that's pretty much all there is to it.
I recently enjoyed a Brandy Smash made by Sebastian, and I wouldn't be surprised if he used Jerry's recipe:
By the way, a digital copy of Jerry Thomas' 1862 bartenders' manual How to Mix drinks: or, the Bon-Vivant's Companion is available through google books! Just click the title to take a peek.
(Use small bar-glass.)
1/2 table-spoonful of white sugar.
1 do. water
1 wine-glass of brandy.
Fill the glass two-thirds full of shaved ice, use two sprigs of mint, the same as in the recipe for mint julep. Lay two small slices of orange on top, and ornament with berries in season.