Heat sugar, corn syrup and water in a 2-quart pan on low heat until sugar is dissolved, stirring constantly, then cook without stirring to 260 degrees on candy thermometer or until small amount dropped in very cold water forms a hard ball. Remove from heat. Beat egg whites until stiff. Continue beating while slowly pouring hot syrup in egg whites. Add vanilla. Beat until mixture holds its shape and loses its shine. May be too stiff for electric mixer, so beat by hand. Fold in nuts. Drop on wax paper by spoonfuls. Yield: about 4 dozen.