The mechanical clock was built to solve a religious problem. Monastic communities had to pr at fi hours thr the ni, and nei candles n water ves kept reli time i a co building. Falling weights turned out to be far steadier, and the escapement that released them in regular steps is the invention on which every later clock, down to the wristwatch, ultimately depends. Nobody at the time was interested in minutes.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.