Note 76 — Chapter XI · Epoch of Young and Fresnel.
Reading edition
I may mention, in addition to the applications which Young made of the principle of interferences, his Eriometer, an instrument invented for the purpose of measuring the thickness of the fibres of wood; and the explanation of the supernumerary bands of the rainbow. These explanations involve calculations founded on the length of an undulation of light, and were confirmed by experiment, as far as experiment went.