D’Arcy Thompson had a lot of correspondence with the Scottish physicist and applied mathematician William Peddie (18611946) 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 .
Back to the Logarithmic Spiral
Introduction

Overview & D'Arcy's Life

On Growth and Form

Heilmann & Shufeldt

Maths of Transformations

Correspondence

D'Arcy and Mathematics

Coordinate Transformations

Logarithmic Spirals

Forms of Cells

Forms and Mechanical efficiency

Shrinkage

Wartime and D'Arcy

The Leg as a Pendulum

Recreational Maths

Fibonacci Sequence

CellAggregates

Claxton Fidler

Eric Harold Neville

John Marshall

Alfred North Whitehead

Charles Robert Darling

Peter Guthrie Tait

William Peddie

Geoffrey Thomas Bennett

Dorothy Wrinch



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:
http://www.mcs.stand.ac.uk/~dat/