Talk:Solar eclipse of August 18, 1868

Helium discovery
These paragraphs were taken from the individual wiki bios (Janssen/Lockyer), no direct references, so I moved here until confirmed: SockPuppetForTomruen (talk) 11:10, 17 January 2010 (UTC) Pierre Janssen observed the solar eclipse in Guntur, Andhra Pradesh, India, where he noticed a bright yellow line with a wavelength of 587.49 nm in the spectrum of the chromosphere of the Sun. This was the first observation of this particular spectral line, and one possible source for it was an element not yet discovered on the earth. Janssen was at first ridiculed since no element had ever been detected in space before being found on Earth.  Norman Lockyer observed the solar eclipse from Vijaydurg, India, and observed a prominent yellow line from a spectrum taken near the edge of the Sun from. With a wavelength of about 588 nm, slightly less than the so-called "D" lines of sodium. the line could not be explained as due to any material known at the time, and so later it was suggested by Lockyer that the yellow line was caused by an unknown solar element. He named this element helium after the Greek word 'Helios' meaning 'sun'.

Thank you. As I know:


 * Janssen was in Guntur in 1868 aug 18 and did observe the solar eclipse with a spectroscope (he was one of the six European eclipse-expeditions in India and one of the three teams working at Guntur that day). And he didn't work in vain: he analysed the spectrum of the chromosphere, and during the next weeks, invented a new kind of spectroscope, the spectrohelioscope. Lockyer invented a similar instrument independently.
 * As Kragh writes, there's no written evidence for that Janssen saw the D3 line in the chromosphere spectrum of the Sun (maybe there is, but I haven't found any on the net, looking for original astronomy and chemistry articles in scientific journals and googlebooks reprints), despite of that more than one serious source say that (e.g. Béla Kálmán, astonomer or Kochbar ).
 * I suppose Lockyer was not in India that thay (18 Aug), in this year he was in GBritain (But two months later, on 20. Oct. [Kálmán writes] he analysed the sun with his own spectroscope, as Janssen before. It is supposable that Lockyer  did it in Britain, and as Kálmán explicitely writes: in daylight, without eclipse).
 * Lockyer did percept the d3 line on 20th Oct. Later he wrotes about it explicitely in a lots of his works (maybe in his report to the Academy also - or maybe not. I don't know.).
 * That is an acceptable fact Lockyer and Janssen both wrote a report to the French Academy, and it is curious, but these reports arrived to the Academy on the same day. In 1872 the Academy published a coin with the picture of Lockyer and janssen, because of their important examinations on the Sun protuberancies and independent invention of spectrohelioscope-technology (as I know, this technology makes the emission spectal analysis of the Sun possible in "daylight", filters out too strong photosphere frequencies preventing the analysis of chromosphere, so we don't have to wait for eclipses - or does something similar :-). But as Helge Kragh wrotes, none of their reports deals with either D3 line, either helium.

But my sources are not unambiguus enough, for example Kragh writes about Janssen's exploration of D3 line, it seems to me, despite he questioning that, doesn't know if it is a mere legend or more. So I can't correct the article yet. Gubbubu (talk) 20:45, 17 January 2010 (UTC)


 * I put some sources onto the Helium talk page, but from what I read it took until 1871 when the word helium was first used. The D3 line was mentioned many times from 1868 on, but that it is due to a new element yet unknown nobody stated during the first few months. --Stone (talk) 14:07, 20 December 2010 (UTC)

French Siam expedition
One of the two French expeditions to observe the eclipse was sent to Siam (now Thailand). The three Édouard Jean-Marie Stephan Georges Rayet and Félix Tisserand observed the eclipse together with the kink of Siam Mongkut at Waghor (11°43'2"N  99°45'21"E) several kilometres south of Prachuap Khiri Khan. The kink provided calculations for the best viewing point of the eclipse and set up a comfortable place for the French and English scientist and spectators.

The second French expedition went to India and set up their camp in Guntoor close to two English expeditions. Led by the French astronomer Pierre Janssen the expedition yielded spectra of solar protuberances which led to the discovery of helium.
 * The Total Solar Eclipse of August 1868. Part I.
 * The Total Solar Eclipse of August 1868. Part II.

One German expedition with Friedrich Tietjen, Engelmann Spörer d'Anclam and Koppe also set up their equipment in India into a small village Mulwar close to Bijapur.

The other German expedition, with Bernd Tiele, Vogel, Zeucker and Frisch conducted their observations from Arabia, close to Aden

The Austrian expedition was also located in Aden. The expedition was led by Edmund Weiss.


 * Sorry, the information above is wrong. The French expedition had their own viewing point some kilometers away from the King's viewing point. More details in the German Wikipedia. --Plenz (talk) 09:51, 22 April 2012 (UTC)

German wikipedia translation
See: