Guido of Arezzo
In the 12th century, a development in teaching and learning music in a more efficient manner had arisen. Guido of Arezzo's alleged development of the Guidonian hand, more than a hundred years after his death, allowed for musicians to label a specific joint or fingertip with the gamut (also referred to as the hexachord in the modern era). Using specific joints of the hand and fingertips transformed the way one would learn and memorize solmization syllables. Not only did the Guidonian hand become a standard use in preparing music in the 12th century, its popularity grew more widespread well into the 17th and 18th century. The knowledge and use of the Guidonian hand would allow a musician to simply transpose, identify intervals, and aid in use of notation and the creation of new music. Musicians were able to sing and memorize longer sections of music and counterpoint during performances and the amount of time spent diminished dramatically.
Clock face
Before the late 14th century, a fixed hand (often a carving literally shaped like a hand) indicated the hour by pointing to numbers on a rotating dial; after this time, the current convention of a rotating hand on a fixed dial was adopted. Minute hands (so named because they indicated the small, or "minute", divisions of the hour) only came into regular use around 1690, after the invention of the pendulum and anchor escapement increased the precision of time-telling enough to justify it. In some precision clocks, a third hand, which rotated once a minute, was added in a separate subdial. This was called the "second-minute" hand (because it measured the "secondary minute" divisions of the hour), which was shortened to "second" hand. The convention of the hands moving clockwise evolved in imitation of the sundial. In the Northern hemisphere, where the clock face originated, the shadow of the gnomon on a horizontal sundial moves clockwise during the day. This was also why noon or 12 o'clock was conventionally located at the top of the dial.