"He is usually represented with three books. In Callot's _Images_ he is treading on serpents, and accompanied by the text Numb. xxi. 7. Both these emblems allude to his opposition to Arianism; the books signifying the treatises he wrote against it, and the serpents the false doctrines and heresies which he overthrew." _Calendar of the Anglican Church Illustrated_: London, 1851, p. 37. In Didron's splendid work (the _Iconographie_) we have several references to ancient representations of our blessed Lord treading the dragon under foot; and sometimes the lion, the asp, and the basilisk are added. (See Ps. xci. 13.) _The Conception_ is usually represented in Christian art by a figure of Mary setting her foot, as second Eve, on the head of the prostrate serpent (in allusion to Gen. iii. 15.), and thus we find it in Callot's _Images_. "Not seldom, in a series of subjects from the Old Testament, the pendant to Eve holding the apple is Mary crushing the head of the fiend: and thus the bane and antidote are both before us." (See Mrs. Jameson's _Legends of the Madonna._) EIRIONNACH. [Footnote 5: The title of this curious book is, _Geschichte der Mission der evangelischen Brueder unter den Indianern in Nordamerika_, durch Georg H. Loskiel: Barby, 1789, 8vo., pp. 783. Latrobe's translation of this book was published Lond. 1794.] [Footnote 6: This reminds one of the notion respecting "The scorpion girt with fire," immortalised by Lord Byron's famous simile.] [Footnote 7: _Eighteen Books of the Secrets of Art and Nature; being the Summe and Substance of Naturall Philosophy methodically digested_: London, 1661.] [Footnote 8: In O'Brien's work on _The Round Towers of Ireland_, London, 1834, may be found much curious matter on this subject; and a good deal of light is thrown on the horrors of Serpent or Boodhist worship. It is, however, a wild and irreverent book, and by no means to be recommended to the general reader, independently of the nature of its details. Mr. Payne Knight's book is too well known to need mention here.] * * * * * PHOTOGRAPHIC CORRESPONDENCE. _Early Notice of the Camera Obscura._--I send you an early notice of the camera obscura, which is to be found in vol. vi. of the _Nouvelles de la Republique des Lettres_ for September, 1686, p. 1016. It is taken from a letter of Mons. Laurenti, medecin, of Boulogne, "Sur l'erection des especes dans une chambre optique."