A is the nominal of the sixth note in the natural diatonic scale, or gamut - the sixth diatonic step of the first or lowest octave of the modern scale - to which Guido (ARETINUS, or ARETINA, called Guido and Guidone) originally applied the monosyllable LA. A is the sixth ; a indicates the same step in the second octave. As the Italic capital A is used in the first instance, and the small Italic a in the next, the former is called the large or great octave, the latter the small octave. The mark which represents the same note in the third octave is 
, with one line above it, and 
with two lines above it represents the same note in the fourth octave. These last, being designated by lines, are named the one-lined octave and the two-lined octave, and so on, because the number of lines denotes the number of octaves above the small or second octave. A is also the name of one of the two natural modes, and is the open note of the second string of the violin, and the note by which the other strings of that instrument are tuned and regulated. A is like-wise the name of that note in our system which answers to the lowest sound used by the ancient Greeks ; that is, the proslambanomenos of the Hyperdorian, or deepest Greek mode, which note we now place on the first space in the bass clef. A (the Italian A, sounded broad, as in father) is naturally the first letter, because it represents the first vocal sound naturally formed by the human organs ; being the sound uttered with the mere opening of the mouth, without constraint, and without any effort to alter the natural position or configuration of the lips. A is placed by modern musicians on the first space of the bass staff, or on the first space with the F clef, thus : -
A. was long the lowest sound known. The letter A. has for ages been used as the name of a tone - it was so used by Aristoxenus, 340 years be-fore Christ. It is the name of the first string of he violoncello, by which its other strings are tuned ; and the various instruments of an orchestra, or band, are generally tuned from this letter. The lowest string of the double bass viola is generally tuned to A ; and the tuning fork and pitch pipe are generally keyed on A. This letter is called by all nations, in solmization, LA, thus : -
A not only represents the first natural vocal sound, the sound first made by infants, but it is the first letter of the alphabet in most of the known languages of the earth ; in the Ethiopic, however, it is the thirteenth, and in the Russic, the tenth. A, or the sixth note in our system, it will be observed, corresponds with the proslambanomenos, or lowest sound, of the Greek scale. The more ancient Greek scales formed their septenaries from the letter A ; and the letters below A in the bass were made double, and those above the staff with the G clef were termed in alt; but the septenaries being reckoned from A, the limits of the bass, tenor, and treble were not accurately defined. This letter has in the English language, regularly, only two sounds peculiar to it-self, a short and a long one ; all other sounds of the letter being irregular and various, according to its combination with other letters. A, as the mark of a vocal sound, is the most simple, and that which the dumb are most easily taught to utter. To pronounce it clearly, we need only to open the mouth wider than for any other sound, and then emit the air from our lungs. In music, A has several distinct and different meanings: if any numerical figure is added to the letter A, when prefixed to a vocal composition, it denotes the number of voices for which the piece is in-tended ; as, A 2, for two voices ; A 3, for three voices, &c. It occurs in both vocal and instrumental music, technically, in a great many different connections ; as, a tempo, in time ; a due, for two voices ; a piacere, at pleasure, &c. From the earliest ages, the tones of music were designated by the letters of the alphabet, and the lowest or first tone of the ancient Greek scale was called A; and this tone continued to be the lowest or most grave tone known till about the year 960, when Guido Aretinus added another note below, which he called hypo-proslambanomenos, thus ex. tending the scale down to G in our present gamut. From this time, or from the tune in which Guido flourished as a popular musician and teacher, or about the eleventh century, A, of course, ceased to be the lowest tone. Since the time of Guido, greater changes have taken place in the arrangement of the tones, and C is now the lowest note, thus establishing our present system of naming the seven principal tones, and making A the sixth degree of the diatonic scale. The Greeks used all the letters of the alphabet, making in all 1620 different musical characters, (an endless task, al-most, to learn them ;) but we use only seven, the seven first letters of the alphabet, making A the sixth letter, and submediant in the natural scale, thus : -
A. An Italian preposition, signifying in, for, at, with, &c.
A ABOVE G GAMUT. That A, or that note, which is one tone higher than G gamut.
A ABOVE THE BASS CLEF NOTE. That A, or that note, which is a third higher than the bass clef note.
A ABOVE THE TREBLE CLEF NOTE. That A, or that note, which is one note higher than the treble clef note.