Gold Pair Cased 15 Second Rack Lever by Tobias

An early 19^th Century English rack lever by Tobias with 15 seconds subsidiary in gold pair cases.  Full plate gilt keywind fusee movement with gilt dust cover pierced for the table of the cock.  Chased and engraved cock, diamond endstone in a blue steel setting, marked "Patent" on the table.  Blue steel Bosley regulator.  Plain three arm polished steel balance with blue steel spiral hairspring.  Rack lever escapement with adjustable slides to the lever pivots.  Off white enamel dial, subsidiary seconds marked  to fifteen seconds, the hand mounted on the escape wheel arbor rotating four times every minute.  Roman numerals, blue steel seconds hand, gilt hands.  Matching 18 carat gold pair cases, gold oval pendant and bow.  Maker's mark "TH & Co" and number corresponding to that on the movement.