The meridians are important parts of the terrestrial navigation. Before the era of GPS satellites the only method to determine the longitude of a place on the Earth was the measure of longitude (and lattitude) by astronomical methods. For these measurement the so called transit equipments, the passage instruments were used. Both meridians and the instruments used to measured them can be found on medals and coins.
The famous Greewich, i. e. the zero meridian can be found on several medals. One of these is a so called geocoin. The geocoins - which are accessories of a new kind of technical hobby, geocaching - cover a wide range of topics. On the obverse we can find the meridian facing to Royal Observatory. The meridian continues vertically on the wall. In the legend around is the name of the observatory, Royal Observatory, Greenwich, below its geographical coordinates are shown. Longitude of the meridian is not exactly zero because Sir George Airy fixed the new zero point to the new instrument he made and set up in 1851, by which the old meridian was pushed by 5.79 meters to west. This difference is expressed by the small difference from zero.
On the reverse of continuation of the meridian can be seen viewing from the building. Legend around is "Prime Meridian of the World,". The legend below and the letters in the image on the coin are part of geocaching, and are not belong to the subject of coin.
A medal issued in 1984 remembers about the centenary of 1884, when on the International Meridian Conference organized in Washington D. C., “the Conference proposes to the Governments here represented the adoption of the meridian passing through the center of the transit instrument at the Observatory of Greenwich as the initial meridian for longitude. (Ayes, 22; noes, 1; abstaining, 2.).” On the obverse of the gold-plated metal medal the map of the Earth crossed by the zero longitude can be seen. Legend around "LONGITUDE ZERO" and "1884 GREENWICH 1984" are the aforementioned two year numbers.
On the reverse of the coin – as on the previous one – the housing of the passage telescope can be seen but here all the doors and the roof opened, in measuring ready state. Legend around is "PRIME MERIDIAN OF THE WORLD", below "EAST WEST".
Liberia issued an interesting coin to celebrate the start of year 2000. On its obverse the Greenwich meridian is named, and the number 2000 is displayed in a form that three zeroes of it represent the zero degree, minute and second of the base meridian. The coin has a face value of $1, and famous buildings of the world decorate the coin aroind the rim.
On the reverse of the coin is the coat of arms of Liberia and legend: "REPUBLIC OF LIBERIA 1 DOLLAR". The issue date 2000 is also visible.
Not oly the zero meridian is famous. The meridian at 15° is the center for Central European Time Zone. The German town Görlitz lines on this meridian, and proud of it. They issued a 40 mm diameter copper medal showing the meriadian at 15°0 and lattitude 51° 10' N. The legend is: "STADT AM 15. MERIDIAN", i. e. town at the 15th meridian. The coat of arm of the town is also pictured. The legend below is: "DIE IN DER DDR GÜLTIGE MITTELEUROPAISCHE ZONENZEIT (MEZ) STIMMT IN GÖRLITZ MIT DER SONNENZEIT ÜBEREIN.", i. e. where the Central European Time (CET) in GDR matches with the solar time.
On the reverse of the medal the coat of arms of the former East Germany and the city is palced along with a bridge. Legend is: "GÖRLITZ - STADT AN DER ODER - NEISSE - FRIEDENSGRENZE", i. e. town at the Oder–Neisse peace borderline.
Another famous meridian is what Giovanni Domenico Cassini, the Italian origin French astronomer measured in Bologna. The San Petronio Basilica in Bologna incorporates this line that is visible even today. The obverse of this silvered metal medal shows Cassini's right facing portrait. Legend around is: "IO · DOM · CASSINVS · ARCHIGVM · BONON · PRIMAR · ASTRON · ET · R · ACAD".
On the reverse of the medal the cross section of the San Petronio Basilica with the median line is visible. The medal shows the effect when throuh a hole the Sun projects itself to the line at noon. The legend above: "FACTA · COPIA · COELI". Below "BONON", i. e. Bologna and the date "M·DC·VC", 1695. Cassini later went to Paris, and served there for 40 years as astronomer of the king. During this time Cassini's method of determining longitude was used to measure the size of France accurately for the first time. The country turned out to be considerably smaller than expected, and the king quipped that his astronomers had taken more land from him than his enemies.
The Kiev observatory can be found on the obverse of a very nice design 5 hryvnia nominal value commemorative coin issued in 2010. Legend under the building in four lines is "АСТРОНОМІЧНА ОБСЕРВАТОРІЯ / КИЇВСЬКОГО НАЦІОНАЛЬНОГО / УНІВЕРСИТЕТУ / ІМЕНІ ТАРАСА ШЕВЧЕНКА" that is, Astronomical Observatory of the Kiev National University named after Taras Shevchenko. Legend around: "НАЦІОНАЛЬНИЙ БАНК УКРАЇНИ", i. e. National Bank of Ukraine, face value: "5 ГРИВЕНЬ" and date 2010.
On the reverse we see the Kiev meridian telescope in the background with the starry sky through the observatory's is open roof. The legend: "КИЇВСЬКИЙ МЕРИДІАН · 1845", that is Kiev meridian 1845, indicates the founding year. The coin was issued in the observatory 165th birthday.
In the 17th-18th century a lot of European town's longitude was measured. István Hatvani, was a medical doctor, mathematician and teacher at the Reformed College of Debrecen. He measured the geographical coordinates of the college on 21st June 1757, as it can be read from the cast medal below. The obverse of this medal shows the building of the college, above it two crossing lines show the longitude and the latitude measured by Hatvani. This is an award medal issued by one of the organizations of the MTESZ (federation of technical and scientific societies of Hungary), the HAJDÚ-BIHAR MEGYEI SZERVETE (a county in Hungary). The medalist was Sándor Tóth, whose signature is visible right below the date on the left.
On the reverse of the medal the portrait of István Hatvani is visible. Legend is: "HATVANI ISTVÁN DÍJ", i. e. István Hatvani Award.