(_ii._) AULUS GELLIUS. Carus Sterne (_Gartenlaube_, 1877) and Ayrton (_Journal Royal Institution_, 1879) refer to Aulus Gellius as having written of mirrors which “sometimes reflected their backs and sometimes did not.” The reference appears to be a mistaken one; for all I have been able to find in Aulus Gellius is the following passage in the _Noctes Atticæ_, bk. xvi., ch. xviii. (which is upon that branch of Geometry called [Greek: optikê]): [Greek: Optikê] facit multa demiranda id genus; (1) ut in speculo uno imagines unius rei plures appareant; (2) _item, ut speculum, in loco certo positum, nihil imaginet, aliorsum translatum, faciat imagines_; (3) item, si rectus speculum spectes, imago fiat tua hujusmodi, ut caput deorsum videatur pedes sursum. The passage which I have put into italics appears to have been mistaken in meaning. In Beloe’s translation, vol. iii., p. 249, this clause is rendered as follows: “A glass placed in a certain position shows nothing. Turn it, and it shows many things.” This is hardly adequate. More accurately it should run: “A mirror set in a certain place shows no image, but when transferred to another position produces images.” There is nothing in this at all suggestive of the mirror reflecting from its face the pattern on its back. (_iii._) MURATORI. Sterne (_op. cit._) and Ayrton (_op. cit._) refer vaguely to the Italian historian Muratori as the authority for accounts of a “magic mirror found under the pillow of the Bishop of Verona, who was afterwards condemned to death by Martin (_sic_) della Scala, as well as of the one discovered in the house of Colla da Rienzi (_sic_) on the back of which was the word ‘Fiorone.’” The bishop in question was Bartolomeo dalla Scala, who was put to death in 1338 by Mastino della Scala, as narrated by Muratori (_Annali d’Italia_, vol. viii., p. 212, of the folio edition of 1744-49). Cola di Rienzo (or Rienzi) is mentioned many times in the same volume viii. I have not, however, been able to find in this work the mention of the mirror in either case. Neither have I found any as yet in Lessmann’s life of Mastino della Scala (Berlin, 1829); nor in Du Cerceau’s _Life and Times of Rienzi_ (Lond. 1836). Muratori was, however, a prolific writer. Amongst his works were: _Delle forze dell’ Intendimento Umano_; _Riflessioni sopra il Buon Gusto nelle Scienze e nelle Arte_; _La Filosofia Morale_. It is possible that the reference may be to some passage in these. Muratori also refers to a _Vita di Cola di Rienzo_, the authorship of which is unknown to me.