Old-Fashioned Pecan Pralines

In a large, heavy pot combine sugar, brown sugar and water; bring to a boil. When sugar is dissolved, add pecans. Reduce heat and gently simmer, uncovered, stirring occasionally. Cook for "about 15 to 20 minutes, until the mixture grains when metal spoon is rubbed against side of pot" (direct quote from original copy). Remove from heat. Add butter and vanilla. Beat mixture with wooden spoon until it appears to granulate and adhere to the spoon. Drop by spoonfuls onto waxed paper or foil. Cool completely.