The problem was to account for the fact that light bodies, such as the seed of lycopodium, collected at the vibrating parts of sounding plates, while sand ran to the nodal lines.

Faraday showed that the light bodies were entangled in the little whirlwinds formed in the air over the places of vibration, and through which the heavier sand was readily projected.

Faraday's resources as an experimentalist were so wonderful, and his delight in experiment was so great, that he sometimes almost ran into excess in this direction.

I have heard him say that this paper on vibrating surfaces was too heavily laden with experiments.
Footnotes to Chapter 2 [1] The reader's attention is directed to the concluding paragraph of the 'Preface to the Second Edition written in December, 1869.

Also to the Life of Faraday by Dr.Bence Jones, vol.i.p.