Recent from talks
Jens Olsen's World Clock
Knowledge base stats:
Talk channels stats:
Members stats:
Jens Olsen's World Clock
Jens Olsen's World Clock or Verdensur is an advanced astronomical clock which is displayed in Copenhagen City Hall. The clock consists of 12 movements which together have 15,448 parts. The clock is mechanical and must be wound once a week. Displays include lunar and solar eclipses, positions of the stellar bodies, and a perpetual calendar, in addition to the time. The fastest gear completes a revolution every ten seconds and the slowest every 25,753 years.
The clock was designed and calculated by Jens Olsen (1872–1945), who was a skilled locksmith, and later learned the trade of clockmaking. He also took part in the beginning of the clock's construction, and died in 1945, 10 years before the clock was completed.
The calculations for the clock were made up until 1928, after which they were supervised by the astronomer Elis Strömgren. The drawings for the clock were made between 1934 and 1936, and the actual production of the clock took place from 1943 until 1955. The clock was started on 15 December 1955 by King Frederik IX and Jens Olsen's youngest grandchild Birgit.
Deviations in expected readings identified in 1991 were caused by increased friction from oil in the pivots hardening from prolonged sun and oxygen exposure. As a result the clock was largely disassembled to be refurbished and upgraded:
The restoration process started in 1995 and concluded in 1997 and was entrusted to Soren Andersen, a Danish specialist in clock making and conservation.
The clock is located centrally in a dedicated room, surrounded by smaller, related displays and descriptions of various aspects of the clock. The clock itself is enclosed in a large glass case with wooden and stainless framing, and sits on a granite base. The clock faces the singular entrance to the room, but visitors can view it from all sides to see the intricacy of the design. The enclosure has internal lighting, and is temperature and humidity controlled by a ventilation plant in the basement of the building. As it exists today the gearing and module structure is largely gold-plated brass, while the dials are rhodium plated.
The escapement is a Dennison-style double triple-leg gravity escapement, a design choice common in later tower clocks that prioritizes accuracy over efficiency. In simple terms, the escapement itself acts as a remontoire such that variations in input torque are largely decoupled and do not influence the pendulum. However, this design choice necessitates significant input power (in the case of the World Clock significant weight) to compensate for the energy surplus that is "dumped" by the air-brake with each tick. The pendulum is a "seconds pendulum" and therefore requires a theoretical length of 994.5 mm for Copenhagen's local gravity, although due to the dispersed mass the physical pendulum is slightly longer to give the correct period. Material selection is diligent: the pendulum rod is Invar, the impulse rods sapphire, and the movement is highly jeweled. The escape wheel is a relatively unusual, 5-tooth design.
The clock movements are modular, such that an observer may more easily identify them and understand the functioning of the clock more readily. Additionally, it permits many movements to be removed and maintained without necessitating stopping the entire clock. The number of escapements is occasionally stated as 11 rather than 12, this ambiguity arises from whether the Mean Time and Sidereal Time are considered a single movement. All but the Equation Works movements have dials on the front of the clock, arranged in left, center, and right sections.
Hub AI
Jens Olsen's World Clock AI simulator
(@Jens Olsen's World Clock_simulator)
Jens Olsen's World Clock
Jens Olsen's World Clock or Verdensur is an advanced astronomical clock which is displayed in Copenhagen City Hall. The clock consists of 12 movements which together have 15,448 parts. The clock is mechanical and must be wound once a week. Displays include lunar and solar eclipses, positions of the stellar bodies, and a perpetual calendar, in addition to the time. The fastest gear completes a revolution every ten seconds and the slowest every 25,753 years.
The clock was designed and calculated by Jens Olsen (1872–1945), who was a skilled locksmith, and later learned the trade of clockmaking. He also took part in the beginning of the clock's construction, and died in 1945, 10 years before the clock was completed.
The calculations for the clock were made up until 1928, after which they were supervised by the astronomer Elis Strömgren. The drawings for the clock were made between 1934 and 1936, and the actual production of the clock took place from 1943 until 1955. The clock was started on 15 December 1955 by King Frederik IX and Jens Olsen's youngest grandchild Birgit.
Deviations in expected readings identified in 1991 were caused by increased friction from oil in the pivots hardening from prolonged sun and oxygen exposure. As a result the clock was largely disassembled to be refurbished and upgraded:
The restoration process started in 1995 and concluded in 1997 and was entrusted to Soren Andersen, a Danish specialist in clock making and conservation.
The clock is located centrally in a dedicated room, surrounded by smaller, related displays and descriptions of various aspects of the clock. The clock itself is enclosed in a large glass case with wooden and stainless framing, and sits on a granite base. The clock faces the singular entrance to the room, but visitors can view it from all sides to see the intricacy of the design. The enclosure has internal lighting, and is temperature and humidity controlled by a ventilation plant in the basement of the building. As it exists today the gearing and module structure is largely gold-plated brass, while the dials are rhodium plated.
The escapement is a Dennison-style double triple-leg gravity escapement, a design choice common in later tower clocks that prioritizes accuracy over efficiency. In simple terms, the escapement itself acts as a remontoire such that variations in input torque are largely decoupled and do not influence the pendulum. However, this design choice necessitates significant input power (in the case of the World Clock significant weight) to compensate for the energy surplus that is "dumped" by the air-brake with each tick. The pendulum is a "seconds pendulum" and therefore requires a theoretical length of 994.5 mm for Copenhagen's local gravity, although due to the dispersed mass the physical pendulum is slightly longer to give the correct period. Material selection is diligent: the pendulum rod is Invar, the impulse rods sapphire, and the movement is highly jeweled. The escape wheel is a relatively unusual, 5-tooth design.
The clock movements are modular, such that an observer may more easily identify them and understand the functioning of the clock more readily. Additionally, it permits many movements to be removed and maintained without necessitating stopping the entire clock. The number of escapements is occasionally stated as 11 rather than 12, this ambiguity arises from whether the Mean Time and Sidereal Time are considered a single movement. All but the Equation Works movements have dials on the front of the clock, arranged in left, center, and right sections.
Recent media