Greenwich Meridian & The Royal Observatory

 by Iona Perkins

Evenings are currently getting darker whilst during half term we all enjoyed an extra hour in bed as the clocks went back. This is to help utilise the natural light and is a relatively modern idea, with it only being discussed by the government in 1908 and put into practice in 1916. Daylight saving time helps to manage daylight throughout the different seasons as during winter the sun rises earlier and sets later in summer. It uses Greenwich Mean Time, the yearly average of the time each day when the Sun crosses the Prime Meridian at the Royal Observatory in London. 

The Royal Observatory was commissioned by King Charles II during the Restoration Period and built in 1675. Its plans were developed by Christopher Wren, a famous architect of the time who also reconstructed much of London after the Great Fire of 1666. The location had been chosen carefully as it was on a hill, so had a panoramic view above the pollution, although that did not create nearly as much of a problem as it does today. It was also Charles’ land, so he didn’t have to rent it, using his small budget from parliament. Originally the ruins of Greenwich Castle, it was knocked down,though the foundations remained. The Observatory’s prime position is in the vicinity of both the bustling ports of the Thames, bringing in furs from Canada, tea from India or China or raw materials such as sugar or cotton and Greenwich University. 

It is common knowledge that sailors have used celestial navigation for centuries to help keep their longitude, using stars at night and the sun during the day. However, the inability to calculate latitude accurately when out of sight of land caused many shipwrecks and prolonged voyages. During the explosion of International Trade globally in the Restoration Period, it was crucial to solve the ‘latitiude problem’. Voyages going ever greater distances, to Africa or America or India, meant that the ability to sail faster and with more direct routes would offer economical advantages as fewer sailors would perish and produce could be delivered efficiently. Trade was a necessity for Restoration England as it funded Charles II and provided many job opportunities. It also enabled Britain to project a strong and powerful facade to its rivals, which always has benefits. Puzzled mathematicians, cartographers and astronomers struggled to solve the problem. 

The Octagon room has eight walls, with a large domed ceiling, was constructed with the intention of being used to examine the stars, however none of the several windows pointed north, south, east, west or even up, forcing John Flamsteed, the first Royal Astronomer, to look for alternatives. Flamsteed built a small shed on the property and used this instead to gaze upon the moon and stars, making about 50,000 observations in his 40 year career. Astronomers used Meridian lines (invisible lines going North to South along the Earth) as a reference point for making star observations. By measuring the time and height that they cross these lines frequently, it was possible to create an accurate map of the sky. 

Finally, around 1735, John Harrison solved the problem! He was fascinated with clocks and invented the first chronometer. (He went on to create three more versions, each one smaller and more precise than the last). It is a precise timepiece that compares Greenwich Mean Time with the time at the current location from observations of celestial bodies. The Earth was divided into 24 segments vertically of 15 degrees each and added or subtracted an hour to make 24 in total, each for one hour of the day. Multiply the difference of the two times by 15 degrees an hour and you have your longitude. For example, New York is five hours behind the UK. 

For a while, the chronometer worked and International Trade flourished with its new speed and technological advances. However another problem arose, when ships stopped to confer with other ships and different mean times were confused due to there being Greenwich Mean Time, Paris Mean Time and others. After many months during the International Meridian Conference, in 1884 it was decided that as most ships already used GMT, it would be used as 0 degrees and would expand from there. Therefore, the Prime Meridian in Greenwich is the basis for calculating all international time zones and longitudes and became Britain’s legal standard time in 1880. 

The Observatory is a prime example of the ambition of the time to drive scientific development and to fufill the desire of wanting more; the establishment of new elite scientific organisations, for example The Royal Society and The Royal Observatory proves the determination that intellectuals of that time had the endeavour to lead the way scientifically.