Joking or for precedence in the history of timepieces--The driving power--The escapement--Compensating pendulums--The spring balance--The cylinder escapement--The lever escapement--Compensated balance-wheels--Keyless winding mechanism for watches--The hour hand train. LOCKS:--The Chubb lock--The Yale lock. THE CYCLE:--The gearing of a fern or of life. I did not redeem his pledge.