Note 13 — DRIFTING LIGHT-WAVES.

I have omitted all reference to details; but in reality the double battery was automatic, the motion of the observing telescope, as different colours of the spectrum were brought into view, setting all the prisms of the double battery into that precise position which causes them to show best each particular part of the spectrum thus brought into view. It is rather singular that the first view I ever had of the solar prominences, was obtained (at Dr. Huggins’s observatory) with this instrument of my own invention, which also was the first powerful spectroscope I had ever used or even seen.