“And hereof came it that Fryer
Bakon was accompted so greate a negromancier, whiche never used that arte (by
any coniecture that I can fynde) but was in geometrie and other mathematicall
sciences so expert, that he coulde dooe by theim suche thynges as were
wonderfall in the syght of most people.
“Great talke there is of a glasse
that he made in Oxforde, in which men myght see thynges that were doon in other
places, and that was iudged to be done by power of euyll [evil] spirites. But I
knowe the reason of it bee good and naturall, and to be wrought by geometrie
(sythe [since] perspective is a parte of it) and to stande as well with reason
as to see your face in common glasse.”
The quotation above comes from the preface to a textbook on
geometry called A Pathway to Knowledge
published in London in 1551. It was written by a doctor and mathematician
called Robert Record (1512 – 58). His arithmetic textbook, Ground of the Arts, first published in 1543, was popular with
students by virtue of being in English. It went through over 40 editions right
the way to the end of the seventeenth century.
Record is probably best known for his invention of the equals sign. However, despite his relative success as an
author, he died in a debtors’ prison.
Of course, the quotation is most interesting because it
describes a device that sounds much like a telescope, sixty years or so before
the telescope was supposed to have been invented. “Fryer Bakon” is Roger Bacon OFM, the
Franciscan scholar of the thirteenth century famous for his Opus Maior and Opus Minor who lectured at the Universities of Oxford and Paris. He may have been (but probably wasn’t)
imprisoned for a time for his adhesion to the ultra-ascetic wing of the
Franciscans. His reputation for
necromancy was a not uncommon trope in sixteenth-century England where he was a
famous historical figure. However, the
accusation of black magic is almost always found in the context of a denial
that he was, in fact, a magician.
Record’s preface is a good example of this kind of defence
of Roger Bacon. The specific charge is
that Bacon had a device that allowed him to see what was going on in other
places. Record says the device was not magical
but used Bacon’s knowledge of perspectiva,
what we would call geometrical optics.
Bacon was indeed familiar with this subject and wrote a treatise on
it. In this treatise, he mentions
magnifying glasses and, as it happens, spectacles were invented in Italy
shortly thereafter.
To be clear, there is no evidence that Bacon had any device
to see different places, magical or otherwise.
What interests me is what Record thought
Bacon had invented. The device mentioned
in the quotation does not sound like a magnifying glass or spectacles. In any case, if that was what Record had in
mind, he would just have said so (probably calling a magnifying glass a “perspective
glass”, which confusingly was also an early term for the telescope).
I think there are three possible interpretations of Record’s
words:
- Record has no idea what he thinks Bacon’s device was. He just wants to reassure his readers that it would have been built on mathematical and not necromantic principles. This is possible. Record is making a point that geometry is jolly useful. But the passage reads as if he knew what the device was supposed to be and how it worked.
- Record thinks the device was a periscope. These had been invented a hundred years before Record wrote by Johan Gutenberg, who lost money on the venture. Gutenberg later had more success as a pioneer printer. The trouble is, periscopes don’t really show you what is going on in another place. But they do allow you to see around corners, so this interpretation is a possibility.
- Record has in mind a device like a telescope that really does let the user see things where he isn’t. Hans Lippershey famously patented the first telescope in 1608, but several others claimed to have invented it. This certainly best fits the context of the passage but would require that Record knew what a telescope was before it was supposedly invented.
So could Record really know about a telescope as early as
1551? Astronomer Colin Ronan has claimed that it was invented by a Kentish mathematician and astronomer called Leonard
Digges (d 1559). The claim is actually
made by Digges's son Thomas (d. 1595) on his father’s behalf. Digges Jr produced an edition of his father’s
book on practical geometry called Pantometrica
which was published in 1571. In the
introduction, he notes:
“… my father by his continual
painful practices, assisted with demonstrations Mathematical, was able, and
sundry times hath by proportional Glasses duly situate in convenient angles,
not only discovered things far off, read letters, numbered pieces of money with
the very coin and superscription thereof, cast by some of his friends of
purpose upon downs in open fields, but also seven miles off declared what hath
been done at that instant in private places.”
This does sound a lot like the device mentioned more briefly
by Record in the preface to The Pathway
to Knowledge. It would be great to be
able to link Record and Digges directly.
Unfortunately, Record was based in Cambridge in the 1540s, Digges in
Kent. But Record was reasonably
well-known after 1543 thanks to his arithmetic book Ground of the Arts. Among the small community of English
mathematicians, Digges and Record, both avid Protestants, could have met.
Overall, I think there is a good chance that Record is
referring to a telescopic device in 1551 and if so, this is most likely to be the
same one that Digges had invented. At
least, Record seems aware that a telescope exists even if he has not seen one. If this is the case, it is evidence that
Digges really did create telescope before 1551 and makes Record’s preface the
earliest reference to it.
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