A Baconian instrument: the beard of a wild-oat

One of the oddest experiments of Sylva is the one in which Bacon discusses an “experiment of jugglers,” using the “beard of an oat”. The jugglery uses one of the important properties of plants, that of detecting and absorbing water. The beard of the wild-oat is a very porous body, which can be used as a hygrometer. It was used so in the seventeenth century by Robert Boyle and Robert Hooke (see the image below for Hooke’s hygrometer).

hooke-higrometerLike many other experiments discussed in the Sylva Sylvarum, the beard of the wild oak can be found in Giovan Battista Della Porta’s Magia naturalis (book XX, Chapter VIII). Della Porta is also presenting (and exposing) a jugglery which makes use of the weird property of the wild-oat to change position and twist when absorbing water. In the English translation of Della Porta, the wild-oat is described as follows:

If you search in Barley, you shall finde a small ear of wilde Oates, that is black and wrestled, like the foot of a Locust; and if you binde this with wax to the top of a knife, or point of a stile, and shall sprinkle softly some drops of water upon them, when it feels the wet, it will twist like a Harp string (p. 406)


Bacon’s experiment is much more complex and it involves a rather confusing description of a set of tricks played by jugglers. At the bottom of all the tricks, however, there is the same property. And the whole discussion is meant to exemplify “what a little moisture will do in vegetables, even thought they be dead and severed from the earth” (experiment 494).

For a Romanian translation of experiment 494 see here.

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