A clock replaced the good old bell. Effectively, two hands of a clock replaced a tongue or the clapper of the bell. The clock could do by itself all that the bell couldn’t. To begin with the clock couldn’t be heard afar like the bell, so they built a bell inside the clock. ​The word clock actually comes from the French for Bell.​Yes, an alarm was added to the clock which would do exactly what the bell did. The Bell Towers of yore were replaced by Clock Towers with easy availability of large size clocks in the 15th century.