Note upon some phenomena of binocular vision

Chemistry and the spectrum before Bunsen and Kirchhoff

“…In spite of this, the decade preceding Bunsen and Kirchhoff's successful work saw a number of investigators groping in the right direction. Foucault (31) examining the spectrum of an arc between charcoal electrodes, noticed a line similar to the D line of the solar spectrum. Lacking suitable instruments for independent measurement of the lines, he attempted to superimpose the two spectra by passing the sun's rays through the arc and through the prism.…”