Hugh Farey wrote in a comment yesterday:
It was of huge benefit to have actual shroud fibres to compare experimental ones with, and I would never attempt to dismiss Rogers’s observations out of hand. Nevertheless I am not convinced by some rather sweeping statements that do not, to my mind, correctly describe the nuances of what is actually seen under a microscope. I have yet to see a photo that demonstrates that a shroud image fibre is not coloured throughout its diameter. Indeed, I would aver that Rogers’s Figure VI-2 in his Chemist’s Perspective book demonstrates exactly the opposite. “An unusually deeply coloured image fibre” he captions it.
I am also intrigued by the “scorching in the medullas.” As the medullas (Does he mean lumens?) are essentially hollow tubes, what precisely is scorched? Having spent weeks now looking at scorched firbres under a microscope myself, I think those black lines may in fact be on the surface of the fibres, not in the middle. The lumen is usually wider than those black lines, and indeed, if I magnify his Figure VI-1 till it fills the screen (I have the online version of his book) I can see what I think are the sides of the interior, uncoloured, lumen, on either side of the black line supposedly marking the ‘medulla.’
It is the business of the scientist to attempt to falsify hypotheses, and the business of the hypothesis to defend itself. Sadly, Ray Rogers is no longer able to answer my observations on his observations, which perhaps he could have done with other photomicrographs. However, as it stands, I still cannot consider the case against scorching proven.
Gabriel asked Hugh to provide them and he did along with this explanation:
Here are the two photos I was talking about. The first, showing (to me, at least) a uniformly coloured fibre with a clear lumen, is from elsewhere in your blog, but in Rogers’s book as VI-2. The second is a massive enlargement of VI-1, showing a scorch fibre. I think the black crease is a surface phenomenon, while the two arrows point to the sides of the lumen, uncoloured, deeper within the fibre. (It was a bit of a devil to extract from the pdf, so you’ll probably have to crop off the white surround or something; I couldn’t do it somehow). I had a warning from Thibault, quite justified, that I wandered into microscopy at my peril, but I do think my photos clearly show what I say I see, whereas a lot of the published ones are indistinct, to say the least. If anyone spends hours sweating over a hot microscope, surely he illustrates his findings with the best photos he can manage, and although I do understand that the earler ones were taken without the benefit of a digital camera or photomanipulation, they are not always clear enough to be convincing.
VI-2
VI-1
Hugh, thank you for photos. I think that it would also be most interesting having access to the photos from your own scorching experiments. You are reinterpretating Rogers photo from another perspective which to me seems estimulating.
If I understand your point correctly, it is the shroud image fibers that are coloured throughout their diameters (VI-2) while the scorched fibers get coloured only on their surfaces (VI-1 outer and inner). If this is the case, and the image fibers are coloured beyond their surface and this is not only an exceptional example, what happens with the impurity layer theory? Also, if this is the case, images VI-2 and VI-1 seem to be too different as to explain as a scorch also what we see in the image fiber VI-2.