I was fascinated by the beautiful video analysis of elephants' gaits performed by J. R. Hutchinson et al. (Nature 422, 493–494; 2003) but surprised to find no mention of Etienne-Jules Marey, who pioneered an analysis of elephant motion, photographically, in 1887 (E. J. Marey & C. Pagès, C. R. Acad. Sci. 105, 149–156; 1887).
It is true that Eadweard Muybridge had photographed elephants in motion a couple of years earlier, but he did not mark up the salient joints as Marey did, and so could not measure vertical movement at the hip or shoulder. Moreover, his use of a battery of 24 separate cameras could not provide a “chronophotograph”, as Marey called it, of successive configurations superimposed on a single plate. (Marey secured this by using an ordinary camera with a slotted-disc shutter rotating behind the open lens.) Such photographs, and the diagrams that could be extracted from them, were necessary if one was to analyse the biomechanics involved.
Marey's elephants (see illustration) were marked in the same way as those of Hutchinson and colleagues. His motion analyses, which were far more probing and extensive than Muybridge's, are described very fully in Marta Braun's Picturing Time: The work of Etienne-Jules Marey, 1830–1904 (University of Chicago Press, Chicago, 1992).