[ISHMap-List] 'Cartographic innovations by the early portolan chartmakers'

Roel Nicolai rnicolai at xs4all.nl
Fri Jan 13 22:02:54 CET 2017


It appears we have indeed reached the natural end of this discussion.
I see little point in a repetition of the arguments I raised against a
medieval origin. I describe them extensively in my book, which, I will
repeat for the last time, contains considerably more than just cartometric
I can only wish you the best in finding evidence that is able to demonstrate
the feasibility of charting based on mental maps only. This goes so much
against my knowledge and against 38 years of experience in mapmaking and
geodesy that I am unable to give serious consideration to that hypothesis.

Best regards,

-----Original Message-----
From: ishm-bounces at lazarus.elte.hu [mailto:ishm-bounces at lazarus.elte.hu] On
Behalf Of Tony Campbell
Sent: Thursday, January 12, 2017 4:34 PM
To: ISHMap-List
Subject: [ISHMap-List] 'Cartographic innovations by the early portolan


I will respond briefly to your latest post.  Given the distance between our
two positions I think it unlikely we will be able to find much agreement,
and I question how long this exchange can usefully continue.

First of all, though, thank you for pointing out the internal contradiction
in my text about the nature of the increase in the number of compass lines
through the centre of his later charts. I have removed the careless and
incorrect statements about '64 directions'.

I now comment only on what I consider to be one or two major issues.

The first is your supposed conviction that portolan chart historians assume
a medieval origin. I don't think most of us are committed to that view.  We
have looked for whatever evidence there might be, whether documentary or in
the charts, but have found no convincing evidence for an earlier origin. Nor
I think have you, beyond extrapolation from cartometric findings.

Where I would argue that there *is* a 'departure point' is in your dismissal
of the possibility that the medieval mind and its technology were capable of
creating the portolan chart. It is surely unwise, given examples from
indigenous wayfinding and mapping techniques, to place a theoretical limit
on what less advanced societies were capable of. 
History depends on documentation, and we would not expect to find a
description of the devising and construction of a portolan chart.

What we *do have* is actual evidence of the process of creation in the
charts themselves, although it is dismissed by you thus in a Delphic
sentence :

"Regarding the Atlantic coastlines; these innovations are unsuitable for
distinguishing between the hypothesis of a medieval and the one of a
non-medieval origin, because both can provide an explanation for the

On the contrary, I consider this to be crucial evidence because we here see
- by degrees, involving different chartmakers and presumably different
informants - the gradual emergence of a recognisable coastline from Cape St
Vincent to Bruges, along with a parallel expansion in the toponomy. All this
occurred between perhaps c.1280 and c.1320. If the sailors of that period
were capable of such an achievement, why not those from a century before?

The general assumption that seems to have been made - perhaps there are
exceptions - is that the portolan charts are the result of some kind of
surveying operations (or of a process we can recognise as that).  Where is
the evidence for that?  As you know, in Lisbon I asked that consideration be
given to the hypothesis that the charts might never have been consciously
'mapped' at all, but rather have emerged from the sharing and adjustment of
the mental maps that any experienced mariner must have had in their head.
The Black Cab drivers' mental map of every London street, and the ability to
get between any pair of those, is a far more impressive feat.

  I do not think that two related questions have ever been properly asked -
and if you have done so please accept my apologies and point me to the
relevant part of your book. How did mariners find their way around and
across the Mediterranean for millennia before the appearance of the portolan
charts; and what advantage did the charts offer them?  I am not sure how
cartometric analysis can help here.

Best regards,


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