I recently read Ken Alder's "The measure of all things" about the first steps of the metric system definition. The project described in the book was the measure the meridian arc between Dunkirk and Barcelona in order to be able to define the meter (equal to one ten-millionth of the quarter meridian). When he was in Barcelona, Pierre Méchain, the astronomer in charge of this part, made different measures in different parts of the city, but one of his results was inconsistent with the others and confused (a lot) Méchain.

Almost 30 years later, in Connaissance des temp pour l'an 1831, p. 58-77 (published in 1828), J.-N. Nicollet, a member of the Bureau des Longitudes (and later known for his maps of the Mississipi river) wrote an article about Méchain's results saying (among other things) that experimental errors should be distinguished between :

  • systematic errors, due for instance to bad calibration of instruments or imperfect methods of observation
  • random errors, due for instance to fluctuations in the measurements or interpretations

So, basically, it's all about better describing the accuracy and make a clear difference between trueness and precision.

I am wondering if Nicollet was the first to make this clear distinction. Before him, who worked on this topic and may have inspired Nicollet ?

Also, I do not see many comments to Nicollet article (only an anonymous one in Philosophical magazine 1829, p.180-188 ). Was there discussions on this topic after Nicollet ? (to challenge, to fine-tune, etc...).


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