(3.) "If a ray of sunlight, broken through a prism, i.e., bent up or down, appears as a coloured band instead of round and white as before, the cause must always be that light consists of homogeneous rays, differently coloured and refrangible to different degrees, which, when forced asunder on account of the difference of their refrangibility, give an elongated and variously-coloured spectrum:
d. gorantz eta beherantz aldenduriko eguzki-irudia, lehenik biribil eta zuri agertu ordez, orain luzanga eta koloreztaturik agertzen bada, horren kausa argian desberdin koloreztatu eta desberdin errefraktaturiko argi-izpi homogeneoak sarturik egotea da beti, zeinak, bere errefraktagarritasun desberdinaren bitartez bata bestetik aldendurik, orain irudi luzanga eta aldi berean kolore desberdinekoa erakusten baitu: