Place sugar, corn syrup and water in a saucepan over low heat. Stir until sugar is dissolved; then cook without stirring until thermometer reaches 255 degrees (Hard Ball Stage).
Remove from heat and pour, beating constantly, in a fine stream into egg whites. Continue beating until mixture holds its shape and loses its gloss.
Add vanilla and nuts. Drop quickly from tip of spoon onto waxed paper in individual peaks or spread in a buttered pan and cut into 1-inch squares when firm. Makes 8 dozen pieces.