Maxwell and The Electrical
Researches of Henry
Cavendish
Isobel Falconer
St Andrews
ICOHP, Cambridge, Sept 2014
Please attribute Isobel Falconer .
Except where otherwise stated,
this work is licensed under a Creative Commons BY-SA 4.0
International License.
1771 paper: An attempt to explain some of the principal
phaenomena of electricity by means of an elastic fluid
1776 paper: An account of some attempts to imitate the
effects of the torpedo
MS of an extended work on the elastic fluid theory
MS methodical account of experiments bearing on the
theory of electricity
Daily record of experiments on
– Electrostatics (capacities of systems of conductors of various
shapes)
– Inverse square law experiment
– Electrical properties of non-conductors
– Conductivity of solutions (related to torpedo)
Harris, 1867, Treatise on
Frictional Electricity
Maxwell, 1879, Electrical
Researches of Henry Cavendish
Harris, 1867, Treatise on
Frictional Electricity
Maxwell, 1879, Electrical
Researches of Henry Cavendish
‘The leading idea which
distinguishes…Cavendish
from…his predecessors… is
the introduction of the
phrase “degree of
electrification”…which…is
precisely equivalent to what
we now call potential’(Maxwell,
1879, Introduction to ER)
‘His measurements of
capacity will give us some
work at the Cavendish Lab.,
before we work up to the
point where he left it’
(Maxwell to Garnett, July 1874)
Photo by
Isobel Falconer
Left: Cavendish’s theory of
(non)conduction in glass
Below: Maxwell’s
comparison of Cavendish’s
data
Above: Cavendish, experiments
with the artificial torpedo
Right: Maxwell, 1879 Plan of an experiment on
the physiological effect of an induction current
(for plan see Harman, Scientific Letters and
Papers of James Clerk Maxwell, vol 3,
(Cambridge: CUP, 2002) p769)
• Maxwell’s Electrical Researches of Henry
Cavendish can be read as a move in the
struggle to establish professional
mathematical physics
– A British and experimental genealogy
• Maxwell’s preoccupations were with:
– evidence for his electromagnetic theory
– furthering the ‘doctrine of method’
• Maxwell inverted Cavendish’s bodily methods,
extending electromagnetic theory to
investigations of the body
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Henry Cavendish, By George Wilson [Public domain], via Wikimedia Commons
William Cavendish, 7th Duke of Devonshire, By Herbert Rose Barraud ([1]) [Public
domain], via Wikimedia Commons
James Clerk Maxwell by G. J. Stodart [Public domain], via Wikimedia Commons
William thomson lord kelvin at the age of twenty two" by Unknown [Public
domain], via Wikimedia Commons
Maxwell & McAlister’s inverse square law apparatus, in the museum at the
Cavendish Laboratory. Photo by Isobel Falconer licensed under a Creative
Commons BY-NC-SA 4.0 international license
William Snow Harris, A Treatise on Frictional Electricity, ed by C. Tomlinson
(London: Virtue, 1867)
Henry Cavendish: The Electrical Researches of the Honourable Henry Cavendish,
ed. J. Clerk Maxwell, (Cambridge: University Press, 1879).
Peter Harman, Scientific Letters and Papers of James Clerk Maxwell, vol 3,
(Cambridge: CUP, 2002)