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
Peddie
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

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

   

Cell-Aggregates

   

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

   


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School of Mathematics and Statistics
University of St Andrews, Scotland

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