The Mountains of the Moon of Ptolemy (Lib. iv. cap. 9,) (σελήνης ὅρος) form on our older maps an immense uninterrupted mountain zone, traversing Africa from east to west. The existence of these mountains appears certain; but their extent, their distance from the Equator, and their general direction, are all unsolved problems. I have already alluded in another work, (Cosmos, vol. ii. p. 191, and note 297, Engl. ed.) to the manner in which a closer acquaintance with Indian languages, and with the ancient Persian idiom, the Zend, teaches us that part of the geographical nomenclature of Ptolemy forms an historic monument of the commercial connection of the west with the most distant regions of Southern Asia and Eastern Africa. The same direction of ideas shews itself in a question very recently brought forward. It is asked, whether the great geographer and astronomer of Pelusium meant in the name of “Mountains of the Moon,” as in that of the “Island of Barley” (Jabadiu, Java), merely to give the Greek translation of a native name;--whether (as is most probable) El Istachri, Edrisi, Ibn-al-Vardi, and other early Arabian geographers, only transferred the nomenclature of Ptolemy into their own language;--or whether they were misled by similarity in the sound of the words and the manner of writing. In the notes to the translation of Abd-Allatif’s celebrated description of Egypt, my great instructor, Silvestre de Sacy, (éd. de 1810, p. 7 and 353,) says expressly: “On traduit ordinairement le nom de ces montagnes que Léon Africain regarde comme les sources du Nil, par _montagnes de la lune_, et j’ai suivi cet usage. Je ne sais si les Arabes ont pris originairement cette dénomination de Ptolémée. On peut croire qu’ils entendent effectivement aujourd’hui le mot قمر dans le sens de la _lune_ en le prononçant ‘Kamar’; je ne crois pas cependant que ç’ait été l’opinion des anciens écrivains arabes qui prononcent, comme le prouve Makrizi, Komr. Aboulféda rejette positivement l’opinion de ceux qui prononcent kamar, et qui dérivent ce nom de celui de la lune. Comme le mot komr, considéré comme pluriel de اقمر, signifie un objet d’une _couleur verdâtre_ ou d’un blanc sale, suivant l’auteur du Kamous, il paroit que quelques écrivains ont cru que cette montagne tiroit son nom de sa couleur.”