William Peddie

Correspondence with Peddie (Logarithmic Spiral)

D’Arcy Thompson had a lot of correspondence with the Scottish physicist and applied mathematician William Peddie (1861-1946) during the years before On Growth and Form. They were colleagues at Dundee University, with Peddie working there from 1907 as Professor of Physics. A large area of the their correspondence concerned spirals and how they relate to actual forms. In one of the key letters (ms45791), Peddie describes in detail the coiling of such a spiral and the mathematics behind it.

Thompson was particularly interested in the overlapping of spirals and Peddie believed this was to do with one coil partly caving in the other. He also had ideas on the way open and closed spirals were formed, using the rotation of one spiral by an angle Φ.
To see the full transcript of Peddie’s letter on equiangular spirals click here .

Peddie's sketch of a logarithmic spiral
Peddie's sketch of a logarithmic spiral
(dashed line spiral caused by rotation of pole by φ).
Spiral becomes closed when φ is 2π. .

Back to the Logarithmic Spiral



Overview & D'Arcy's Life


On Growth and Form


Heilmann & Shufeldt


Maths of Transformations




D'Arcy and Mathematics


Coordinate Transformations


Logarithmic Spirals


Forms of Cells


Forms and Mechanical efficiency




Wartime and D'Arcy


The Leg as a Pendulum


Recreational Maths


Fibonacci Sequence




All Correspondence Links

Claxton Fidler


Eric Harold Neville


John Marshall


Alfred North Whitehead


Charles Robert Darling


Peter Guthrie Tait


William Peddie


Geoffrey Thomas Bennett


Dorothy Wrinch


Main Index Biographies Index

The support of The Strathmartine Trust towards this website is gratefully acknowledged    

Alice Gowenlock & Indre Tuminauskaite © June 2018
Copyright information
School of Mathematics and Statistics
University of St Andrews, Scotland

The URL of this page is: