Pi me a river (Variants 1-4) [mathematical abstract art print, unframed] A4/A3 sizes


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A paper in the journal Science in 1996 put forward the theory, backed up by obscure calculations, that the relationship between the length of the world's rivers, measured by the distance their waters flowed, and the straight line distance from source to mouth, averaged pi (3.14). This became established wisdom and the name of this design was based on the theory.

Which would be nice except that when the theory was tested more recently by actually measuring a large number of rivers it turned out that most of them clustered around 1.94, and it's yet to be explained why. Which just goes to show that the ability to look at numbers and question whether they make sense is vital in resisting the seductive claims of scientists, politicians and business alike.

What is still true is that all the four sinuous lines in this design are the same length - and that IS because of pi.

Designed by David Lawrence, d/dx art prints are created on heavyweight Canson Infinity artboard produced at the centuries-old Arches paper mill in France. This superb artboard is acid-free and uses no optical brighteners to degrade over time. Ultrachrome K3 inks provide vivid colours which will last without fading for many decades in normal conditions. The robustness of the paper makes DIY framing a simple matter.

The prints are standard European A4 (210*297mm) or A3 (297*420mm) in size. They are packed flat in crystal envelopes with cardboard stiffener and posted in a rigid container via Royal Mail first class.

Prints can be initialled "D." using the customization option at the time of purchase. Just add 'Initialled please' or something similar!

Shipping & Policies

Payment Methods

  • Accepts Etsy gift cards


We accept credit card, debit card, etsy gift cards, and PayPal payments through Etsy.

Shipping from United Kingdom

We post items wherever possible within 2 working days. Prints are posted in rigid boxes via Royal Mail (First Class within the UK).


Returns & Exchanges

I gladly accept returns and exchanges

Just contact me within: 14 days of delivery

Ship items back to me within: 30 days of delivery

I don't accept cancellations

But please contact me if you have any problems with your order.

The following items can't be returned or exchanged

Because of the nature of these items, unless they arrive damaged or defective, I can't accept returns for:

  • Custom or personalized orders
  • Perishable products (like food or flowers)
  • Digital downloads
  • Intimate items (for health/hygiene reasons)

Returns and exchange details

In the unlikely event that there is a flaw in your print we are happy to exchange it or refund the price on return. In the event of damage in transit, it helps if you can provide photographic or other evidence so that we can claim from Royal Mail.


The colours you are seeing on your monitor are inevitably not precisely the colours you would see if you were looking at the same design in printed form. There is simply no way around that, since the internet places limits on the range of colours that can be displayed and, even if that were not the case, every monitor is subtly (sometimes wildly!) different in the way it displays colours.

But you can be reassured that the quality of our equipment is such that colours and quality are consistent over time and the print you receive will be identical to other prints sold in galleries and art fairs to buyers who have every opportunity to handle and assess them.

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