OBS. 12.—­Final s sometimes occurs single, as in alas, atlas, bias; and especially in Latin words, as virus, impetus; and when it is added to form plurals, as verse, verses:  but this letter, too, is generally doubled at the end of primitive words of more than one syllable; as in carcass, compass, cuirass, harass, trespass, embarrass.  On the contrary, the other consonants are seldom doubled, except when they come under Rule 3d.  The letter p, however, is commonly doubled, in some words, even when it forms a needless exception to Rule 4th; as in the derivatives from fillip, gossip, and perhaps also worship.  This letter, too, was very frequently doubled in Greek; whence we have, from the name of Philip of Macedon, the words Philippic and Philippize, which, if spelled according to our rule for such derivatives, would, like galloped and galloper, siruped and sirupy, have but one p.  We find them so written in some late dictionaries.  But if fillipped, gossipped, and worshipped, with the other derivatives from the same roots, are just and necessary exceptions to Rule 4th, (which I do not admit,) so are these; and for a much stronger reason, as the classical scholar will think.  In our language, or in words purely English, the letters h, i, j, k, q, v, w, x, and y, are, properly speaking, never doubled.  Yet, in the forming of compounds, it may possibly happen, that two Aitches, two Kays, or even two Double-ues or Wies, shall come together; as in withhold, brickkiln, slowwoorm, bayyarn.

OBS. 13.—­There are some words—­as those which come from metal, medal, coral, crystal, argil, axil, cavil, tranquil, pupil, papil—­in which the classical scholar is apt to violate the analogy of English derivation, by doubling the letter l, because he remembers the ll of their foreign roots, or their foreign correspondents.  But let him also remember, that, if a knowledge of etymology may be shown by spelling metallic, metalliferous, metallography, metallurgic, metallurgist, metallurgy, medallic, medallion, crystallize, crystalline, argillous, argillaceous, axillar, axillary, cavillous, cavillation, papillate, papillous, papillary, tranquillity, and pupillary, with double l, ignorance of it must needs be implied in spelling metaline, metalist, metaloid, metaloidal, medalist, coralaceous, coraline, coralite, coralinite, coraloid, coraloidal, crystalite, argilite, argilitic, tranquilize, and pupilage, in like manner.  But we cannot well double the l in the former, and not in the latter words.  Here is a choice of difficulties.  Etymology must govern orthography.  But what etymology? our own, or that which is foreign?  If we say, both, they disagree; and the mere English scholar cannot know when, or how far, to be guided by the latter.  If a Latin diminutive, as papilla from papula or papa, pupillus from pupus,