Page:Encyclopædia Britannica, Ninth Edition, v. 17.djvu/118

106 M U S M U S sounded loudly at the same time they give rise to the appearance of certain other notes within the ear, which are called combination tones. Call the vibration num bers of the two notes p and q. Then the first combina tion tone (Tartini tone, difference tone) has the frequency p q. Other combination tones are also formed, whose fre quencies are of the forms p -2q, p- 3q, and so on. Each of these has its region of greatest intensity when its frequency is smallest consistently with its forming an audible sound. Thus the first difference tone (p-q) is most powerful when p and q differ only by one or more semitones, though the note is still recognizable by the beats it produces when p and q are a fifth or an octave apart. The beats of mistuned consonant intervals other than the beats of harmonics are produced by the formation of im perfect unisons between combination tones and primaries, or among the combination tones themselves. Intervals of the form h : 1. These comprise the inter vals formed between fundamental and harmonics. The beats of mistuned consonances of the form h : 1, other than the beats of harmonics, consist of variations of in tensity of the lower note of the pair. This rule has been established experimentally by the employment of the pure notes furnished by bottles blown from an organ-bellows. Octave. Let the notes be 100 : 201. p q = lQ, which with 100 gives one beat per second. Twelfth. Let the notes be 100 : 301. p- 2g = 101, which with 100 gives one beat per second. Double octave. Let the notes be 100:401. p-3q=lOl. One beat per second as before, and so on. These explanations satisfy the observation that the beats are on the lower notes of the combinations. Other Consonant Intervals. The chief remaining con sonance which furnishes beats is the fifth. There is no doubt that the beats of the fifth, other than the beats of harmonics, are chiefly on the octave below the lower note. Hence the following explanation : Fifth. Let the notes be 200 : 301, p-q=lQl 2q-p = 99 2 beats per second, an octave below the lower note of the pair. Triad with Mistuned Third. If a fifth be tuned per fect and a third inserted, the note two octaves below the lowest note of the triad can generally be heard distinctly. If the third be mistuned, beats are heard on that note. Let the notes be 400, 501, 600, 501-400 = 101 600-501= _99 2 beats per second, two octaves below the lowest note of the triad. There can be little doubt that the definition of con sonances as intervals which can be tuned free from beats lies at the basis of almost all music. There can also be little doubt that the power of the perception or memory of absolute pitch, though sparely distributed, must ensure to those musicians Avho have it influence on the progress of the art. With these persons the influence of conson ance or smoothness is generally subordinate to the recog nition of the pitch of the notes used. Between these two elements scales of different kinds have been evolved in different parts of the world. These scales have almost invariably a basis of consonances, generally fifths. But when once developed the melodic effects almost invariably supersede the reference to the consonances in the ears of expert persons. The scales of different countries and systems, embodied in melodies, sound atrocious to those accustomed to other scales, quite independently of the consonant relations on which they are all founded in common. The subject of Temperament deals with the general theory of the construction of scales from slightly mistuned consonances. (R. H. M. B.) MUSICAL-BOX, an instrument for producing by me chanical means tunes or pieces of music. The modern musical-box is an elaboration of the elegant toy musical snuff-box in vogue during the 18th century. The notes or musical sounds are produced by the vibration of steel teeth, or springs cut in a comb or flat plate of steel. The teeth are graduated in length from end to end of the comb or plate, the longer teeth giving the deeper notes ; and, where necessary, by filing or loading with lead the individual teeth are accurately attuned. Each tone and semitone in the scale is represented by three or four separate teeth in the comb, to permit of successive repetitions of the same note when required by the music. The teeth are acted upon and musical vibrations produced by the revolution of a brass cylinder studded with projecting pins, which, as they move round, raise and release the proper teeth at due intervals according to the nature of the music. An entire revolution of the cylinder completes the performance of the special pieces of music for which the apparatus is set, but upon the same cylinder there may be inserted pins for performing as many as thirty-six separate airs. This is accomplished by making both the points of the teeth or springs and the projecting pins which touch them very fine, so that a very small change in the position of the cylinder is sufficient to bring an entirely distinct set of pins in contact with the note teeth. In the more elaborate musical-boxes the cylinders are removable, and may be replaced by others containing distinct sets of music. In these also there are combinations of bell, drum, cymbal, and triangle effects, &c. The revolving motion of the cylinder is effected by a spring and clock-work, and the rate of revolution is regulated by a fly regulator. The head quarters of the musical -box trade is Geneva, where the manufacture gives employment to upwards of a thousand persons. The musical-box is a type of numerous instruments for produc ing musical effects by mechanical means, in all of which a revolving cylinder or barrel studded with pins is the governing feature. The principle of the barrel operating by percussion or by wind on reeds, pipes, or strings governs carillons or music bells, barrel organs, mechanical flutes, celestial voices, harmoniphones, and the sometimes huge and complex orchestrions in which a combination of all orchestral effects is attempted. A principle of more recent introduction than the studded cylinder consists of sheets of perfo rated paper or card, somewhat similar to the Jacqnard apparatus for weaving. The perforations correspond in position and length to the pitch and duration of the note they represent, and as the web or long sheet of paper passes over the instrument, the perforated holes are brought in proper position and sequence under the influence of the suction or pressure of air from a bellows, and thereby the notes are either directly acted on, as in the case of reed instruments, or the opening and closing of valves set in motion levers or liber ate springs which govern special notes. The United States are the original home of the instruments controlled by perforated paper known as orguinettes, organinas, melodeons, &c. MUSK, a substance of powerful and most enduring odour, is a secretion of the male MUSK DEER (q.v.). Three kinds of musk are distinguished in commerce, the most important and valuable being the Chinese or Tong-king musk, imported principally from Shanghai. It is put up in small tin-lined silk-covered caddies, each contain ing from two to three dozen pods. These are generally adulterated to an enormous extent with dried blood, frag ments of leather, leaden pellets, peas, ifec., so that often