Note 299 — BOOK II. AN ACCOUNT OF THE WORLD AND THE ELEMENTS.

We may presume that the trabes are, for the most part, to be referred to the aurora borealis. The chasma and the appearances described in the twenty-seventh chapter are probably varieties of this meteor. On these phænomena we have the following remarks by Seneca: “Lucem in aëre, seu quamdam albedinem, angustam quidem, sed oblongam, de noctu quandoque visam, sereno cœlo, si parallelo situ sit, Trabem vocant; si perpendiculari, Columnam; si, cum cuspide Bolida, sive Jaculum.” Nat. Quæst. vii. 4, and again, vii. 5, “Trabes autem non transcurrunt nec prætervolant, ut faces, sed commorantur, et in eadem parte cœli collucent.”