'Burning Glasses' in Ancient India, another question

[kellner at ue.ipc.hiroshima-u.ac.jp]

In article <Pine.3.89.9504211802.A539084628-0100000 at HUSC3.HARVARD.EDU>
WITZEL at HUSC3.HARVARD.EDU writes:

>> This interesting topic of the little studied *ratna* lore has been 
>> treated at length by Wilhelm Rau in his Academy paper:
>> 
>> "Die Brennlinse im alten Indien" [The burning glass in Old India"],
>> Akademie der Wissenschaften und der Literatur, Mainz, Abhandlungen der 
>> Geistes- und sozialwissenschaftlichen Klasse, Jahrgang 1982, Nr. 10,  
>> Wiesbaden:Steiner 1983, [pp. 26]  
>> 
>> He traces its use in India to the times before our era.
>> 
A side-question to the original query - I remember a colleague of mine
once speculating about whether Indian authors of epistemological texts
(dharmakiirti, in particular) were aware of burning glasses, lenses or other,
similar man-made devices which would influence perception. The main
question was related to perceptual errors, for explanation of
perceptual errors would probably differ if they had to take into
account artificial devices which alter perception (is what I see
through a magnifying glass real?). Rau's book is not accessible to
me at the moment, and I suspect that he would not deal with the
relation between "scientific invention" and epistemological theory
anyway. So, the question -

Is anybody aware of textual evidence which would suggest that
Indian authors of epistemological texts (in the first millenium A.D. or
earlier) knew of the existence of such artificial devices,
which would interfere with perception?

Birgit Kellner
Institute for Indian Philosophy
University of Hiroshima