Quite a lot has cropped up on the web about Margaret Watts-Hughes's 'Eidophone' in recent years. The Cymatics crowd talk a lot about it (it kind of is Cymatics, but from the late 19th Century). Louise O'Connor and Nick Laessing have made some and performed with them. What you won't find, however, is any more than a very few images of her 'Voice Figures' - that is to say the ones that were available from the 'Making of America' archive, but which now seem to have disappeared (unless of course I've got that wrong - quite possible). This does her work a disservice, so here are some scans from the 2nd edition of her 'Eidophone Voice Figures' pamphlet, which is the better of the two. Sorry about the British Library's watermarks, but hey, you can't have it all...
Watts-Hughes was a Welsh soprano who gave up singing when she married, to concentrate on philanthropy and scientific research. It was during an attempt to measure the power of her voice that she discovered by accident the Chladni-style patterns that she has become known for. Using seeds placed on a rubber membrane stretched over a container into which she sang, she reasoned that by recording how high the seeds leapt, some kind of measure could be got of the voice's health and sonorousness. Although she wasn't expecting patterns to emerge, her inquiring mind drove her to experiment into all kinds of formulations of powders, mixing them with fluids to produce various effects, and eventually hitting on the idea of using pigmented paste smeared on glass plates to record what she produced.
Watts-Hughes ran an orphanage for boys (yes - she was that amazing) and hung her work in the windows around the house:
Instead of blinds or curtains drawn across the lower panes of the windows, there are wonderful designs in colour, strange, beautiful things suggesting objects in nature, but which are certainly neither exact repetitions or imitations of anything in it. Perfectly drawn designs of shell-like forms, of trumpet and snake-like designs, twisted and involved in complicated curves… strange and suggestive indeed are these window panes that the little boys at Islington have to look through. They see weird caverns at the bottom of the sea, full of beautiful beautiful coloured sea anemones and mussel shells, headless snakes, entanglements of leaf-like forms, all seemingly vital with the same laws of growth as those which inspired the creation of the designs in Nature which they suggested.Quote from Isabel Barrington in The London Spectator, October 26, 1899. In: Curtis, H.H (1919) Voice Building and Tone Placing: Showing a New Method of Relieving Injured Vocal Cords by Tone Exercises. London: Appleton and Co. pp.225-227.
I haven't included the images of natural shapes described in this account as they're well represented elsewhere. These plates are more interesting, I think, because not only do they point to a scientific methodology in what Watts-Hughes was doing (particularly the last one), but also they are time based media, produced by dragging the Eidophone's membrane across the glass as she sang. In that sense, they are kind of proto optical sound recordings; although admittedly not in an analytically useful sense like the 'Phonautograph's', but rather more beautiful.