London - Royal Greenwich Observatory
Harrison's first Timekeeper, Greenwich
Harrison's first Timekeeper This timekeeper took about five years to build. In 1736, it was tested on a sea voyage to Lisbon and back. Harrison was very seasick but the timekeeper worked. It was the most accurate sea clock then known, thuogh not quite accurate enough to merit the ₤ 20,000 reward. Lincolnshire, 1730-35
Harrison's first Timekeeper, Greenwich
Harrison's first Timekeeper This timekeeper took about five years to build. In 1736, it was tested on a sea voyage to Lisbon and back. Harrison was very seasick but the timekeeper worked. It was the most accurate sea clock then known, thuogh not quite accurate enough to merit the ₤ 20,000 reward. Lincolnshire, 1730-35
Bradley's meridian line, Greenwich
Bradley's meridian line James Bradley, third Astronomer Royal, observed with improved accuracy using the telescope (purchased in 1749) that first defined this line in 1750. Owing to the unequal length of solar days, astronomers measure the time using distant stars. Stars cross the meridian of an observer around very 23 hours and 56 minutes. Astronomers' clocks run slightly faster than normal clocks to show sidereal (star) time. You are now standing on James Bradley's meridian line (1750). This is still the reference point for Ordnance Survey maps today. Bradley preferred using this transit telescope (inside the building ahead of you) as it produced a wider range of measurements.
Halley - Transit Room, Greenwich
Halley - Transit Room Right Portrait of Halley by Sir Godfrey Kneller. Below 'Looking at Halley's Comet' by John James Chalon. 1835 The earliest mural quadrant was set up here for Edmond Halley, who became the second Astronomer Royal at the age of 64 in 1720, succeeding his former rival John Flamsteed. Halley had been a famous astronomer since his early twenties, but also made numerous discoveries and inventions in other subjects from the Earth's magnetism to insurance tables. When he arrived at the Observatory, Halley found that Flamsteed's widow had stripped it of all of her husband's instruments and furniture. After re-equipping, he embarkecl on an ambitious 18-year programme of observations to plot the movement of the Moon against the stars. Unfortunately, carelessness in regulating and calibrating his clocks and telescopes made much of Halley's research unusable. Today, he is mostly remembered for the comet that still bears his name.
