During the period of 500-1500 AD, the development of time measuring devices in Europe is known not to have improved in any great way technologically, relying mainly on the use of the sundial and principles of measurement used in ancient Egypt.
These dials were placed above doorways and indicated the midday and four 'tides' or times of the sunlit day. In the tenth-century, one English (UK) model showed the marking of the tides compensated for including seasonal changes caused by the Sun's altitude.
In Italy, during the early-to-mid fourteenth-century, large mechanical clocks housed in towers began to appear in several of the large cities. These clocks appear to have been plagued by the same problem as that of the 'water clock', that of regulating the mechanisms and maintaining the accurate time. This appears to have been due to the oscillation period of the escapement depending on a driving force which had sufficient friction in the drive mechanism.
A technological advance came with the invention of the 'Spring-powered' clock, around 1500-1510, credited to 'Peter Henlein' of Nuremberg (Germany). These were instantly popular although the spring-powered clock did have one problem, that of slowing down when the mainspring unwound. In the sixteenth-century, and even through until the nineteenth-century, these clocks were mainly the reserve of the wealthy, when the reduced size meant it could now be put on a mantle shelf or table. The development of the spring-powered clock was the precursor to accurate time keeping.
'Time is an illusion caused by the passing of linear history.' The Mystic