Silver Rack Lever with 15 Seconds Dial

An early 19^th Century English rack lever with 15 second subsidiary in silver pair cases.   Full plate gilt keywind fusee movement, chased and engraved cock inscribed "Patent" on the foot, blue steel Bosley regulator, Plain polished steel balance with blue steel spiral hairspring.  Rack lever escapement with thirty tooth escape wheel, adjustable slides to the lever.  White enamel dial with subsidiary seconds hand on the escape wheel arbor rotating once every 15 seconds.  Roman numerals, blue steel seconds hand, gilt hands.  Matching silver pair cases, silver oval pendant and bow. , maker's mark "ITF" and number corresponding to that on the movement.