Five-minute clock The famous digital clock (hours = Roman numerals; minutes = Arabic numerals; 5-minute time interval) in Dresden's Semper Opera. It was built in 1841 by Friedrich Gutkaes and Adolph Lange, and is conveniently legible from all seats in the house.

Adolph Lange was born in Dresden on 18 February 1815. After his parents divorced, he found a new home with a merchant family that gave the intelligent lad a sound education. At the age of 15, while he was still attending the polytechnic school in Dresden, he began training as an apprentice watchmaker with J. C. Friedrich Gutkaes. In 1835, Adolph Lange completed his apprenticeship with honours. He remained in Gutkaes' employ for two years and subsequently, as a journeyman, sought out the most respected chronometer makers in Europe to hone his skills. He recorded the insights gained during this phase of his life in his famous journey- and workbook, today one of the most precious documents on the history of German watchmaking. In 1841, he returned to Dresden with a host of new ideas, became a co-owner of and the driving force behind Gutkaes' manufactory. Together with Gutkaes, Adolph Lange constructed the celebrated | five-minute clock in Dresden's Semper Opera. A letter of commendation written by Russian Grand Duke Mikhail dates back to this period as well. It lauds the complicated pocket watch which Adolph Lange has built for the regent. As a token of his gratitude, Mikhail enclosed a precious diamond cravat pin. Apart from his dedication to horological perfection, Adolph Lange was a person of uncommon social sensitivity. The growing level of destitution in the Ore Mountains ultimately urged him to leave his privileged position in Dresden: In 1845, armed with numerous visions and his journey- and workbook, he set out for the poverty-stricken town of Glashütte.