This section is from "The American Cyclopaedia", by George Ripley And Charles A. Dana. Also available from Amazon: The New American Cyclopędia. 16 volumes complete..
G The seventh letter in the Latin alphabet, and in others derived directly from it, as the English, French, German, and Italian. In Hebrew, Greek, and some other alphabets of Phoenician origin, it is the third letter. In English it has two entirely distinct normal sounds: the hard, as in get, and the soft (also represented by J), as in gem. In pronouncing hard G, the root of the tongue is raised so as to close the openings from the pharynx into the nostrils, and then by expelling the breath, vocalized by the vibrations of the membranes of the larynx, the sound is formed. The chief difference between hard G and K is that in the latter the breath issues without vocalization. (For the mode of pronouncing the soft G, see J.) In English, G at the beginning of a word has the hard sound when immediately followed by a, o, or u. The words gaol and mortgagor, when thus spelled, form exceptions to this rule; but they are now commonly written jail and mortgageor. In gu, followed by another vowel, the u is generally silent, as in guard and guide; in a few words, mainly of Spanish origin, as guano and guanaco, it is pronounced as gw (in Spanish as hw, or simply w). In gy, except in a few terms of natural history, the g is pronounced soft, as in gymnastics.
When followed by e or i, G may have either the hard sound, as in get, give, or the soft, as in gem, gin; the general rule, to which there are many exceptions, being that it is hard in words derived from the Saxon, and soft in those from Greek, Latin, and French. At the end of a syllable G is hard unless softened by a final e, as in rag, rage; before an affix commencing with i, the softening e is usually omitted in writing, as in refrangible; if the affix begin with a, the silent e is retained, as in changeable. G enters into combination with several other consonants. In gh, at the beginning of a syllable, the h is silent, the g having its hard sound, as in ghost; at the end of a syllable gh is sometimes silent, as in though, and sometimes it has the sound of f, as in trough; in hough (now usually written, as pronounced, hock) it has the sound of Jo; in ght, the t only is sounded, as in night. In gl and gr both letters have their full sound, the g being hard, by whatever vowel followed. In gn, whether at the beginning or end of a syllable, the g is silent, as in gnaio, deign. Ng in English occurs only at the end of a syllable; it has but one sound, by whatever vowel preceded, as in sang, sing, song, and sung.
In the Greek, Hebrew, and Germanic languages, and some others, G is hard in all positions. In the Romanic languages the rules for its hard sound are generally the same as in English, but its soft sound differs in character in French and Spanish. (See J.) It is never absolutely mute in any language but English, but is nearly so in Spanish before ua, and as a terminal in Danish.-In the calendar G is the last dominical letter. In music, it is the name of the 5th diatonic interval, and the 8th string of the diatono-chromatic scale. It is the clef-altered into the adjoining form-of the violin or the treble. Capital G marks the deepest tone of the human voice, its octave being the small g. It is named sol in sol-mization.
 
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