What device finally made it possible to specify the exact duration of the beat? When was this technological marvel invented?

The embroidered narrative of the Bayeux Tapestry depicts events that led to the ____________ of England

not sure what the answer is!

More typically, symmetrical balance is created through _____________, in which the whole of the work has a symmetrical feeling

a. approximate symmetry b. conceptual unity c. extreme unity d. horizontal balance e. radial balance