A late 19th century French black slate mantel clock

A late 19th century French black slate mantel clock, the eight day movement striking on a bell by Jean-Baptiste Delettrez, stamped 'JBD' and numbered '29236 14', with a gilt brass dial with Roman numerals and worn retailers name and with an unusual hand adjuster below 6 o'clock, in an architectural case, 24.7cm high, 27.5cm wide, 14cm deep.