[ [22] This is true only of the “normal spectrum,” formed by reflection from a “grating” on the principle of interference. In the spectrum produced by refraction, the red rays are huddled together by the distorting effect of the prism through which they are transmitted.
[ [23] Am. Jour. of Science, vol. xx. p. 36.
[ [24] Am. Jour. of Science, vol. xx. p. 41.
[ [25] Report of the Paris Observatory, “Astronomical Register,” Oct. 1883; and “Observatory,” No. 75.
[ [26] Hipp. ad Phaenomena, lib. i. cap. xiv.
[ [27] Cosmos, vol. iii. p. 272 note.
[ [28] Am. Jour. of Science, vol. xx. p. 437.
[ [29] Nature, vol. xxiii. p. 19.
[ [30] An expression used by Mr. Warren de la Rue.
[ [31] Optice, p. 107 (2nd ed. 1719.) “Author’s Monitio” dated July 16, 1717.