Planck’s Cosmic Harmonium 257
the Schiedmayer piano factory of Stuttgart for the Ministry. I was given the task of using
this musical instrument for a study of the untempered, ‘ natural ’ scale. ”^9
Though this represented a radical departure from any research work he had done before,
evidently Planck received this task because of his well-known musical interests and acute
sense of pitch, despite his lack of any prior experimental work in acoustics. Still, he was
well aware of Helmholtz ’ s reliance on the harmonium, which Helmholtz praised “ on
account of its uniformly sustained tone, the piercing character of its quality of tone, and
its tolerably distinct combinational tones, [which] is particularly sensitive to inaccuracies
of intonation. And as its vibrators also admit of a delicate and durable tuning, it appeared
to me peculiarly suitable for experiments on a more perfect system of tones. ”^10 The Eitz
instrument Planck used was ordered by Helmholtz from the same factory that had earlier
provided him a two-manual harmonium so precisely tuned that he could experimentally
compare equal-tempered with “ perfect ” just intonation, which he found decisively superior
(see box 4.1).
Using equal temperament, Helmholtz had noted that “ when moderately slow passages
in thirds at rather a high pitch are played, [the resulting combination tones] form a hor-
rible bass to them, which is all the more disagreeable for coming tolerably near to the
correct bass, and hence sounding as if they were played on some other instrument that
was horribly out of tune. They are heard most distinctly on the harmonium and violin.
Here every professional and even every amateur musician observes them immediately,
when his attention is properly directed. ”^11 Helmholtz became a strong advocate of
“ perfect ” (meaning just intonation) rather than equal temperament, which was then
becoming more and more standard. At the time, he was perceived as crotchety and even
rather eccentric; despite his assertions about professional musicians sharing his views,
when Helmholtz met Johannes Brahms and tried to persuade him, Brahms remained
distinctly unmoved and even dismissive, remarking that “ in musical things, he is an
enormous dilettante, ” though Brahms ’ s close friend, the physician and musician Theodor
Billroth, was a great admirer of Helmholtz.^12 Nevertheless, Helmholtz ’ s advocacy of
older temperaments had its day much later as part of the movement to restore the
“ authentic ” performance practices of the past.^13
Planck thus was stepping into a lively, if somewhat outr é , controversy. That a full pro-
fessor of physics in Berlin would be seconded to this musical investigation for several
years shows the continuing importance of Helmholtzian acoustics, with its strong connec-
tion to musical issues of theory and practice that impinged also on the young science of
musicology. Even though tasked thus by the authorities, Planck said he took to his project
with “ keen interest, ” as if the whole episode were an idyll in which he could function
simultaneously as performing musician and as physicist.^14 His work during that time shows
his growing fascination with the possibilities that emerged. He wrote a brief 1893 paper
describing the Eitz harmonium, which divided the octave into 104 steps (using 52 keys),