Geoscience Reference
In-Depth Information
unidentified spectral lines that could be seen in the spectrum of the Sun's atmosphere when
its face was hidden by the Moon were due to a new chemical element (Norman Lockyer
simultaneously came to the same conclusion). Their discovery led to the element being
named helium (from
helios
the Sun) and was isolated terrestrially in a radioactive ore by
William Ramsay in 1895.
People
John Couch Adams (1819-1892)
Adams taught himself mathematics at school and there developed a passion for astronomy.
He was educated at Cambridge and, when he was only twenty seven, co-discovered the
planet Neptune by mathematical calculation. It was known that the planet Uranus was not
following its predicted orbit since its discovery in 1781 therefore either Newton's laws of
gravitation were wrong or there must be an unknown planet beyond Uranus. Adams
worked from known perturbations to deduce the orbit, position and mass of the body that
must be attracting it and in 1845 bestowed the position of the new planet to James Challis
(1803-1882), director of the Cambridge observatory, who then gave Adams a letter of
introduction to the astronomer royal at Greenwich, G. B. Airy (1801-1892). Adams twice
tried to call at Greenwich but failed to get an appointment with Airy and was brushed aside.
Challis set up a laborious and less than diligent search for a “star” moving near the predicted
position. Simultaneously in Paris, Urbain Le Verrier carried out the same investigation as
Adams obtaining the same result. Le Verrier sent his prediction to J. G. Galle at the Berlin
observatory, where H. C. D'Arrest identified the planet as a new star on a star chart. Adams
went on to make two more notable discoveries in astronomy, one in the orbit of the moon
and the other the Leonid meteor shower. He was appointed as director of the Cambridge
observatory at the age of forty-two in 1861.
The French countered by stating that it was not bound by the Rome conference
recommendation and proposed instead that the meridian should be neutral wonder-
ing should it be in the Canary Islands (as was the case in classical geography as set
out by Ptolemy, whose Prime Meridian was based in the island of Hierro, the most
western land that he knew), or the Bering Straits, or at the Great Pyramid (as pro-
posed by the pyramidologist Charles Piazzi Smyth, the director of the Royal
Observatory in Edinburgh), or the Temple of Jerusalem? The British delegation
replied that the Rome conference had been attended by twelve directors of national
observatories and that therefore the scientific opinion was that zero longitude had
to be based at an observatory because of the precision required. Given that the
observatory had to be in good communication with the rest of the world and a per-
manent location, preferably under government control, the ideal candidates were
Paris, Berlin, Greenwich and Washington. The practical choice was the Greenwich
Observatory because this was meridian used by most sea charts and the cost of
reprinting these charts with a new meridian on them would be ten million dollars.
The Paris Observatory might be relocated because it was near the center of the city,
whereas Greenwich was in a park that was distant from the center of London. Little
did the British delegate conceive that both the work of both observatories would
eventually be relocated, and both would cease to have a scientific function.
Janssen said that he was not pushing the Paris Observatory as the Prime Meridian
but argued that it should be neutral and not cut a continent. France had been the first
country to conceive and execute geodetic observations to map Europe, America and
Africa and therefore it was the scientific principle that should be considered and not
the practical use. The intervention of astronomy or geography would lead the dis-
