File talk:Optics from Roger Bacon's De multiplicatone specierum.jpg

I'm moving further discussion to the talk page so we can sort this out.

Note: The attribution to Grosseteste is uncertain. This image is attributed by the web source to Roger Bacon's De multiplicatione specierum. --SteveMcCluskey

However, the image is attributed to Grosseteste by: Colin A. Ronan. The Cambridge illustrated history of the world's science, 1983. The web source states that it doesn't accept responsibility for its descriptions. --Leinad

The web source (the British Library, which holds the manuscript) does not disclaim all resposibility: They state:

All efforts have been made to ensure the accuracy of the information contained in the above description, but the British Library cannot accept responsibility for any errors that may occur.

They describe the image as:

Shelfmark: Royal 7 F. VIII

Page Folio Number: f.25

Title of Work: De multiplicatione specierum

Author: Bacon, Roger

Production: England; late 13th century

I checked further, and A. C. Crombie, Robert Grosseteste and the Origins of Experimental Science, Fig. 2 describes this diagram as follows:

Diagram illustrating Grosseteste's theory, in De Nat. Loc. (see pp. 122, 149) of the focusing of the sun's rays by a spherical lens; from Roger Bacon's Opus Maius, iv. ii. 2, MS Roy. 7. F. vii, f. 25v....

This is apparently the source of Ronan's confusion. Crombie is describing a diagram in Bacon's Opus Majus that is based on a theory in Grosseteste's De Natura Locorum. There is still some confusion as to whether it is from Bacon's Opus Majus or from his De multiplicatione specierum, but once that detail is sorted out, I recommend renaming this image appropriately. (I know, it is much messier to move images than to move articles, but it should be done). Best wishes --SteveMcCluskey 03:05, 3 September 2006 (UTC)

In almost four years, there has been no further comment on this. I just came across a reference in A. G. Little, Roger Bacon Essays, (Oxford: Clarendon Press), 1914, pp. 386-7. In a description of the manuscripts of Bacon's works, he lists the Tractatus de Multiplicatione Specierum as being in British Museum [now British Library]: Royal 7. F. viii, ff. 13-46^v. This range of folios includes folio 25, which is the source of this image.

The online database of medieval scientific manuscripts, Jordanus, lists De multiplicatione specierum as beginning on folio 13 of British Museum, Royal 7 F VIII and the next treatise in the manuscript, Bacon's tractatus de perspectiue, beginning on folio 47. Thus we have two independent sources agreeing that these folios contain Bacon's De multiplicatione specierum, confirming the British Library's attribution of the diagram to De multiplicatione specierum. --SteveMcCluskey (talk) 03:15, 21 August 2010 (UTC)