The name of the Talaiotic culture comes from conic towers built with stones, probably used as a dwelling, watch towers and defense towers. These tables (“Taules” in Catalan) consist in a vertical rectangular stone and another one placed horizontally on its top, so the name of the table is given by the form of “T”. But… why these old monuments are mathematic? The front of most of them is oriented to the south! This orientation is related to the possible use as calendar in this former culture. The construction of the first monuments in Balearic islands dates from the end of the 2nd millenium BC to the beginnings of the 1st millenium BC. At this moment, these monuments began to proliferate on Mallorca and Menorca (there are 31 only in this small Mediterranean island!) appearing in isolated fashion as a territorial boundary stone.
The tables served as sanctuaries next to other monuments and all of them were built in almost the same latitude (and longitude?). For example, Sa naveta des Turons (latitude = 39.99º and longitude = 3.93º), Torretrencada (latitude = 40.003º and longitude = 3.89º) and Torre d’en Gaumès (latitude = 39.93º and longitude = 4.12º) seems to be aligned!
In 1996, Vicente Ibáñez Orts published his hypothesis on the Table explaining that their design was very well computed and not the result of chance. Regarding Torretrencada, it seems that the monument was built from some mathematical computation indicating that Talaiotic men had a system of writing numbers and a deep knowledge of arithmetic and geometry)
This post has been written by Laura Barber and Anabel Luís in the subject Història de les Matemàtiques (History of Mathematics, 2014-15).
Location: Torretrencada (map)
My trip to Poland and Praghe finished yesterday and I remember that in my first post about the Museum of Technology of Warsaw I didn’t talk about the astronomical room in the second floor of the museum. It has some telescopes, reproductions of satellites and a lot of information about the space and we can also find the corner dedicated to Copernicus and his De Revolutionibus Oribium Coelestium and Hevelius.
There are three reproductions of Copernicus’s astronomical instruments which we can imagine in the hands of this Polish astronomer. First of all, the armillary sphere…
…the paralactic triangle (triquetum) for measuring the angular heigh of the Moon…
… and the solar quadrant used by Copernicus in 1510-1520 in order to watch the Sun:
Johannes Hevelius’ instruments are represented by some old images…
…and there is a representation of his observatory in Gdansk:
The third step in the visit to the Royal Observatory of Greenwich is Flamsteed House.
The Royal Observatory of Greenwich was founded in 1675 when Charles II ordered that a small observatory be built in Greenwich Park and appointed John Flamsteed as his ‘astronomical observator’. Flamsteed’s task was to make observations that would improve astronomical navigation, in particular providing a means of finding longitude at sea.
The ceiling of the first room is painted with a map of the night sky and there are portraits of the ten Astronomers Royal who lived here between 1676 and 1948:
Christopher Wren was responsible for building the Observatory. He later said that it was designed ‘for the Observator’s habitation & a little for Pompe’. The following four rooms were Flamsteed’s living quarters. They were incorporated into the enlarged home of the Astronomer’s Royal over the next two and a half centuries. Beyond these, upstairs, is the magnificient Great Star Room, or Octagon Room.
The Octagon Room is one of the few surviving interiors designed by Wren and it was used mainly for observing eclipses, comets and other unusual celestial events.
The 32-inch Astronomical Quadrant is located in this room. It is signed by John Bird but the telescope which was once attached is missing.
The engraving of the Octagon Room by Francis Place shows a similar, earlier quadrant standing on a wheel-tripod platform, which allowed the astronomer to roll it from window to window.
On the wall behind the quadrant we can see three replicas of the clocks which were made in 1676 by Thomas Tompion and sold by Flamsteed’s widow some years later. There is also a replica telescope tube of the kind used here until 1765. Will my daughter be able to discover a new planet?
If we go downstairs now we’ll discover an exhibition about the determination of the longitude at sea:
Where am I?
At sea, navigation is a matter of life and death. Out of sight of land, how can you tell where you are?
By 1700, skilled seamen could find their position north or south (their latitude), but still lacked accurated instruments or methods to calculate their east-west position, known as longitude.
With growing international trade, the lives and valuable cargoes lost in shipwrecks made solving this ‘Longitude Problem’ urgent for all sea-going nations.
The exhibition starts with these two 17th-century globes from North Africa (left) and Persia (right) and then you meet the star of the ‘Longitude Problem’:
Finding longitude – the timekeeper method
One solution to the Longitude Problem was an accurate and portable sea-going clock. By 1726, news of the Longitude Prize had reached John Harrison, a carpenter and self-taught clockmaker from Lincolnshire. Harrison was already making highly accurate land-based clocks and had solved major problems to do with temperature change and friction.
Harrison spent the next 45 years of his life developing portable sea-going timekeepers that would accurately, in spite of a ship’s motion and temperature changes. Each timekeeper represented years of obsessive labour.
By 1760, Harrison had solved the Longitude Problem with his fourth marine timekeeper, now known as H4. It is one of the most important machines ever made.
Harrison’s first timekeeper [H1]
This timekeeper took 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-going clock then known, though not quite accurate enough to win the 20.000 pounds prize.
This prize was offered in 1734 by the British government for a ‘practical and useful’ method enabling ships to determine their longitude at sea.
In the exhibition there are also some timekeepers more and the portraits of some of the most important scientific men which lived in the same time as Harrison: Halley succeeded Flamsteed as Astronomer Royale and his major programme was to replace all the astronomical instruments which were sold by Flamsteed’s widow, and to chart the Moon’s 19-year cycle.
Newton advised the Parliamentary committee that established the Longitude Prize and became a member of the Board of Longitude:
Finally, apart of the camera obscura, we can find outside the Family Tombstone of Halley which was moved to the Observatory from the churchyard of St. Margaret’s in Lee when Halley’s tomb was restored in 1854. The tomb itself is still located at St. Margaret’s with a replica tombstone in place:
As you have seen, you must visit the Royal Observatory in Greenwich if you visit London: it’s only a few metro stops from the center of the city!
The Royal Observatory of Greenwich was commisioned in 1675 by Charles II and the building was completed in the summer of 1676. John Flamsteed (1646-1719) was the first Astronomer Royal so the building was often given the title “Flamsteed House” in reference to its first occupant.
In one of the walls, the observatory has the Sepherd 24-hour Gate Clock which is the earliest electrically driven public clocks. It was installed in 1852 ans the dial always shows Greenwich Mean Time (GMT):
In the small plate under the clock (G 1692) is an Ordnance Survey bench mark dating from the 1940s. The height above the sea level has been measured and recorded. There are also the British Imperial Standards of Length which were mounted here some time before 1866.
The observatory is also known as the location of the prime meridian of Greenwich meridian:
All the tourist want to have a picture with a foot in each side of the meridian:
and there is always a large queue to take a picture next to the meridian line which is graved ion the terrace:
Another characteristic thing of the obervatory is the Time Ball. The red time ball on top of Flamsteed House is one of the world’s first visual time signals. It was installed in 1833 to enable navigators on ships in the Thames to check their marine chronometers.
The Time Ball drops daily at 13:00hrs (GMT in winter […]). It is raised halfway up the mast at 12:55hrs as a preparatory signal and to the top 2 minutes before it drops.
Let’s start our visit through the gardens of the observatory where we can imagine the great English astronomers looking at the night sky! Ofcourse we find a sundial:
Sundials are the oldest known device for telling the time. As the Earth rotates and the Sun appears to move accross the sky, the shadow cast on the scale indicates the time of the day.
This dial constructed in 1968, represents a globe made from a series of rings. The rings are called ‘armillae’ in Latin, so it is called an armillary dial. The hour scale is on the northern half of the ring representing the equator.
There is also the well where Flamsteed 100-foot telescope was located:
Flamsteed used a 30,5 m. well on this site to accomodate a very long telescope:
The astronomer sat at the bottom of the well and observed stars that passed directly overhead. It was hoped that placing the telescope in the well would make it possible to create a steady long-focus instrument for very fine measurements. Flamsteed made a few observations from here in 1679, but the damp underground conditions soon made the telescope impossible to use.
A remaining section of a 12 m. reflecting telescope built for the astronomer William Herschel is also in the gardens:
The telescope was the largest in the world and cost over 4.000 pounds, paid for by King George III. Completed in 1789 and erected at Herschel’s home near Slough, about 30 miles (48 km) west of Greenwich, it soon became a tourist attraction. Some people likened it to the Colossus of Rhodes, and it was even marked on the 1830 Ordnance Survey map of the area.
Sadly, the Herschels did not use the great telescope for much serious astronomy since it was difficult to set up and mantain. William’s son had it dismantled in 1840. Most of the tube was destroyed when a tree fell on it 30 years later.
On the walls of Flamsteed House is marked the Bradley Merdian which was the first British National Meridian. The Greenwich meridian was set according to the location of the telescope used by the Astronomer Royal to establish the time. So the Greenwich meridian was in the graved line when James Bradley, the 3rd Astronomer Royal between 1742 and 1762 was in the observatory. When the Airy Transit Circle Telescope was erected in 1850, the Greenwich Meridian was moved approximately 19 feet east to its present location.
Before visiting Flamsteed House there is still time for look at the Dolphin Sundial designed by Christopher St. J. H. Daniel and commisioned by the National Maritime Museum in 1977:
So let’s go now to Flamsteed House!
Today we have visited the Royal Observatory in Greenwich. In the picture you can see the Queen’s house between the Chapel at the Old Royal Naval College (the building in the right) and the King William Court (in the left). The observatory is on the top of a hill and before visiting it, it’s very interesting go into these other three buildings and the National Maritime Museum to learn a lot of things about the 16th, 17th and 18th-century science.
The gateway of the main entrance to the gardens is decorated with two glass terrestial globes which are a very good appetizer to the museums:
The chapel was originally designed by Christopher Wren but it wasn’t finished until 1752:
The ceiling of King William Court is decorated with a wonderful painting in which we can see some representations of the calendar and the English glorious colonial past:
For example, there is the zodiacal sign of the Lion pointing to the summer…
…or an armilar sphere and a terrestial globe indicating the glory of the Englis navigators…
… and a parallactic ruler and the compass…
… or the telescope:
In the second room there is another great painting in which we can see some angels…
… studying Maths!
Next step in the visit has been the building of the Royal Observatory but this is a story for another post.
Today is Nasîr al-Dîn al-Tûsî’s 812th birthday. Here yoy have his Doodle! It has been published today in a lot of Arabic countries and I don’t know the reason why there is a telescope in the picture. It was invented some centuries later!!!