The consideration of temperature as affecting the use of a standard pitch was not attended to when the French Government issued its ordonnance. The i5° C attached to the description of the standard fork in Paris was intended for the definition and verification of the fork only. The alteration of the fork due to heat is scarcely perceptible, but wind instruments, and particu larly the organ, rise almost proportionately to the increase in temperature of the surrounding air, because sound travels at an enhanced rate as the temperature rises. The coefficient of this rise is equivalent to half a vibration (o.5) per degree Fahr. per second. The French Commission, in establishing the diapason normal, should have chosen a temperature of 2o° C. There would then have been less disturbance owing to the breath of the players and heat of the theatres or concert-rooms. As things are, even the established diapason normal implies a variation from 435 to 44o vibrations a second for a', inasmuch as temperature must always be reckoned with.
In writings on music the pitch of a note is indicated in various ways when it is desired to convey this without the employment of actual notation. Thus organists speak of "great C," "double
C" and "tenor C" to indicate the notes sounded by pipes of f 6ft., 8ft. and 4ft. respectively, the same notes being also indicated alternatively by the lettering CCC, CC and C. Another system is based on the employment of different types (i.e., either capitals or small italic letters), supplemented by small strokes, placed above or below the letters as the case may be. Thus under this system f 6ft. C is represented by C', 8ft. C by C without any stroke, 4ft. C by c, the C above ("middle C" on the pianoforte) by c', the C above that (or treble C) by c", the C above that again by cm, and so on, the intermediate notes in each octave being of course similarly indicated. Or instead of strokes small numerals are sometimes used, e.g., C1, c', etc. The expressions "in alt" and "in altissimo" are also employed for the same purpose, "in alt" signifying the notes in the octave beginning with the C above the treble octave (g") and "in altissimo" those in the octave above (g'", a"', , etc.). (See ALT.) (A. J. H.; X.)