Yet, it was nearly one hundred years later before a seconds hand was finally developed for the swinging pendulum clocks of William Clement.
However, as timekeeping was important to astronomers, having an apparatus that could tell time consistently was of some importance. Therefore, Taqi-al-Din, like Burgi, also sought to provide a more consistent and minute reading of time. Taqi-al-Din designed three dials, which showed the hours, degrees and minutes. In his clock, he incorporated the use of several escapements, an alarm, the striking trains that sounded at every hour, the visual relationship between the sun and the moon, the different phases of the moon, the devices that indicated the time for prayers and the dials that showed the first day of the Gregorian months. (Al-Hassani)
Al-Hassani goes on to describe the escapement as "the heart and soul of a clock…governing its regularity [and] enabling it to move in an incremental manner."
He also notes that modern clocks often use the escapement even today.
Elsewhere in Europe, clocks were being transformed in all sorts of new ways -- even before Galileo's pendulum principle had been applied. At the turn of the sixteenth century in Nuremberg, Germany, for example, Peter Henlein had developed "the first portable (but not very accurate) timepiece" (Bellis). Mary Bellis also makes special mention of French philosopher Blaise Paschal as being the first man to wear a "wrist watch," which Paschal fashioned by attaching a pocket watch to his wrist via a piece of string.
Henlein's spring-powered clock "could fit on a mantle or shelf [and] became very popular among the rich. [it] did have some time-keeping problems, though, as the clock slowed down as the mainspring unwound; [however] the development of the spring-powered clock was the precursor to accurate timekeeping" ("The History of Timekeeping").
Henlein's device was improved upon by Huygens' pendulum clock, whose pendulum was actually somewhat short and beat multiple times in a single second. Huygens' clock was put in wood and mounted on a wall, and gradually refined till its margin of error was less than ten seconds per day ("The History of Timekeeping").
However, the "grandfather clocks" we know today were the work of William Clement, whose pendulum was much longer than Henlein's. Like Huygens', Clement's clock was also encased in wood. And since the long pendulum of Clement allowed even greater accuracy in the clock, in 1670 Clement applied the minute hand to the dial, which Burgi had applied to Brahe's astronomy clock a century before.
The pendulum clock continued to be refined, and in 1721, George Graham "improved the pendulum clock's accuracy to within a second a day by compensating for changes in the pendulum's length caused by temperature variations." Finally, the mechanical clock received so much attention that it "achieved an accuracy of a hundredth of a second a day and became the accepted standard in most astronomical observatories" ("The History of Timekeeping"), paving the way for the first mechanical alarm clock invented in 1787 by Levi Hutchens of New Hampshire (Bellis).
In conclusion, the history of timekeeping saw rapid evolution with respect to mechanical timepieces beginning with the Renaissance and continuing even into today. Beginning as tools for astronomers and mathematicians in the ancient world, clocks became more and more mechanized for a number of different purposes -- whether to serve astronomers who studied the sky, merchants who ran businesses, monks who said prayers, or nobility who could afford the luxury of such devices. Scientists such as Galileo, Burgi, Taqi-al-Din, Huygens and Clement, all had a hand in shaping the mechanical clock as it continued to evolve at the end of the medieval world and into the beginning of the modern age.
Al-Hassani, Salim. "The Astronomical Clock of Taqi Al-Din: Virtual Reconstruction."
Muslim Heritage. 19 June 2008. Web. 15 Mar 2011.
Bellis, Mary. "Clock and Calendar History." About.com Inventors. Web. 15 Mar 2011.
De Solla Price, Derek. The American Clock. Greenwich, CT: New York Graphic
Society Limited, 1973. Print.
Fabian, Sharon. "Telling Time in the Renaissance." edHelper. 2009. Web. 15 Mar
"The History of Timekeeping." Beagle Software. 7 Jan 2010. Web. 15 Mar 2011.