Key

/kee/, n.

Francis Scott, 1780-1843, U.S. lawyer: author of The Star-Spangled Banner.

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I

In music, system of pitches and harmonies generated from a scale of seven tones, one of which is predominantly important.

Keys are a basic element of tonality and represent an outgrowth of modal music (see church mode). When a given piece is "in C," C is its "tonic," or central tone. Most Western music after с 1600 is written in either a major or a minor key. The major scale consists of the interval pattern tone-tone-semitone-tone-tone-tone-semitone. The minor scale consistently differs from it by beginning with the pattern tone-semitone-tone, producing a minor third rather than a major third above the tonic.

II

(as used in expressions)

Fitzgerald Francis Scott Key

Key West

key cryptographic

Key David McKendree

Key Francis Scott

novel with a key

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▪ lock device

      in locksmithing, an instrument, usually of metal, by which the bolt of a lock (q.v.) is turned.

      The Romans invented metal locks and keys and the system of security provided by wards. This system was, for hundreds of years, the only method of ensuring that only the right key would rotate in the keyhole. The wards are projections around the keyhole (inside the lock) that make it impossible for a plain key to be turned in it. If, however, the key has slots cut in it that correspond to the projections, the slots clear the projections, the key can be turned, and the bolt is thrown back. Throughout the centuries immense ingenuity was exercised by locksmiths in the design of the wards, and, consequently, some keys are very complicated. All the same, it was not difficult to make an instrument that could be turned in spite of the wards, to achieve what is known as “picking” a lock.

      Little progress was made in the mechanism of the lock and key until the 18th century, when a series of improvements began that led, in the 1860s, to the development of the Yale cylinder lock, with its thin, convenient key capable of many thousands of variations. The key is made in a number of different cross sections so that only a particular variety of key will fit into a particular keyhole; this, in effect, is a form of ward. The serrations on the edge of the key raise pin tumblers to exactly the correct height, allowing the cylinder of the lock to revolve and withdraw the bolt. Although not impossible to pick, these locks are convenient and compact and offer a reasonable degree of security. In the late 20th century they were the most usual form of fastening for an outside door and were made by locksmiths in all parts of the world.

      A special system is that of the master key. This system is used when a number of locks (such as those securing bedrooms in a hotel), each having a different key, must all be opened by a landlord or caretaker using a single key. Where the only security is by wards, a skeleton key that avoids the wards may be the type of master key chosen. In other cases, many methods are employed; for instance, there may be two keyholes (one for the servant key, the other for the master), or two sets of tumblers or levers, or two concentric cylinders in a Yale lock.

▪ machine component

      in machine construction, a device used to prevent rotation of a machine component, such as a gear or a pulley, relative to the shaft on which it is mounted. A common type of key is a square bar that fits half in a groove (keyway) in the shaft and half in an adjoining keyway in the component. If the shaft and the key are of the same material, a key with a width and depth equal to one fourth of the shaft diameter will have the same torque capacity as the solid shaft if its length is 1.57 times the shaft diameter. These proportions are closely approximated in practice.

▪ music

      in music, a system of functionally related chords (chord) deriving from the major and minor scales (scale), with a central note, called the tonic (or keynote). The central chord is the tonic triad, which is built on the tonic note. Any of the 12 tones of the chromatic (chromaticism) scale can serve as the tonic of a key. Accordingly, 12 major keys and 12 minor keys are possible, and all are used in music. In musical notation, the key is indicated by the key signature, a group of sharp or flat signs at the beginning of each staff.

      The concept of key is fundamental to the system of tonality (the organization of notes, chords, and keys around a centrally important tone), the basis of most Western art music from about 1700 to the 20th century and beyond. A short piece of music, such as a song or dance, may demonstrate only a single key and is said to be in that key; longer pieces usually change key, even many times, but are organized and unified within a principal key that predominates at important points. A composition, particularly an instrumental work, may be identified with a key designation; Beethoven's Symphony No. 2 in D Major (1802), for example, has three of its four movements beginning and ending with explicit harmony in D major (the second movement is in A major, for contrast).

      Different keys are closely or distantly related according to the number of notes their diatonic scales share; C major and G major, for instance, have six of their seven notes in common (differing only in F♮ and F♯) and thus are closely related. In contrast, the distantly related keys of C major and C-sharp major have no note names in common. The relationships between keys are at the heart of the tonal system, and the listener's ability to perceive different keys and the process of changing between them (called modulation) adds immeasurably to their significance in musical structure.

 The circle of fifths is an efficient way to visualize keys, key signatures, and relationships between keys. Beginning at C, the top position, and proceeding clockwise, the keynotes ascend by perfect fifths (as in the tonic–dominant relationship). Each advance adds a sharp to the key—or, equivalently, subtracts a flat. At F-sharp major, the key with six sharps, the circle shifts enharmonically to G-flat major, the key with six flats (they sound and look the same on a keyboard instrument). Each minor key is also entered on the circle, in the same position as its relative major. Thus the circle of fifths clearly depicts the two most important relationships in tonal harmony: tonic–dominant and minor–relative major.

      The broader term tonality is sometimes used loosely for key, e.g., “The first movement of Beethoven's Fifth Symphony exhibits a strong C-minor tonality.”

Mark DeVoto

 

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