Endnote 10
Part I, §5, l. 8.  principals.  It it not unusual to find adjectives of French origin retaining s in the plural; only they commonly follow their nouns when thus spelt.  Cf. lettres capitals, i. 16. 8; sterres fixes, i. 21. 4.  On the other hand, we find principal cercles, i. 17. 34.