Daily loss or gain of velocity. As before, we encounter our sceptical 'as if.' It is then actual, and we also should eagerly close with the free escape of gas lighting 386 Chapter XX.--VARIOUS MECHANISMS. CLOCKS AND WATCHES:--A short 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.