A clarinet is a
woodwind instrument with a single
reed. Modern clarinets are most often black and made of either
plastic or
wood, although I've seen transparent and even red and yellow ones (oh, the
horror!). A clarinet has a straight
bore, in stead of a
conical one like any other woodwind instrument.
Because of the straight bore, a clarinet does not overblow at the octave, but rather at the 12th. Or, in simpler terms: woodwind instruments have a speaker key. When you blow a certain note and add the speaker key, you get the same note, only one octave higher. When you do the same thing on a clarinet, however, the note you get is not an octave higher, but an interval of a 12th higher. This feature gives the clarinet its larger register.
Evolution of the clarinet
The clarinet's predecessor was the chalumeau, also known as the shawm. The chalumeau was the first true single reed instrument. It appeared somewhere in the 1600's. It had two keys, its range was low and it wasn't very flexible. It looked like a small wooden trumpet, with tone holes and a reed.
Exactly when and where the first 'real' clarinet was made isn't very clear, as it's hard to make the distinction between an early clarinet and the chalumeau. It is widely accepted, however, that the first clarinet was made somewhere around the year 1700 by a German instrument maker called Johann Christoph Denner, from Nuremburg. He is said to have been the first person to improve the speaker key and is therfore credited with being the inventor of the clarinet.
In 1690 Denner made an 'improved' chalumeau with seven tone holes and two keys. Somewhere around 1700 he placed the keys in such a way that the instrument could be overblown at the 12th instead of at the octave. Denner also gave the instrument a separate mouthpiece and the bell (the flared bit at the end). Around 1710, Jacob Denner, the son of Johann, made a clarinet with the keys at positions that allowed a clearer upper register, which was also slightly easier to tune. Around 1740 a third key was added, enabling the clarinet to play the third line b-natural.
The clarinet became a popular instrument during the 18th century because of its versatility and large range. More and more composers began to write music for it and this in turn led to more improvements in the instrument itself, to make chromatic playing and tuning possible. By 1778 a clarinet with five keys had appeared and most clarinet players in orchestras were 'real' clarinet players, in stead of oboists with a second job. The five keyed clarinet remained the main clarinet used in orchestras and solo music literature, until the early 19th century, when Ivan Muller's made significant innovations to the clarinet.
In 1812 Ivan Muller invented a clarinet with 13 keys. This clarinet remained popular until the late 1800's. Around 1839-1843 the Böhm fingering system, that was originally invented for the flute, was adapted for the clarinet. This intricate system with its many keys and springs is the one most common today, although other fingering systems are in use, such as the Albert and Auler (mostly in Germany.) The basic idea of the Böhm system was to place the holes in acoustically logical places in stead of placing them for anatomical comfort. Although the earlier systems were better with regard to tonal quality, the Böhm system made for an instrument that was tunable and stable. The Böhm system is in use on the flute, oboe, saxophone and in a hybrid version on the bassoon. The Böhm clarinet has 17 keys and 6 rings.
The sound of German clarinets is rather different from French clarinets. It is a darker, denser sound. The difference is in the bore, though the key system probably also has some influence over the difference in sound quality. Oehler's clarinet, for example, has 22 keys, five rings and finger plate. With these additional keys and mechanisms, the tone and pitch of certain notes is
dramatically improved. The drawback is that the technique required is far more complex.
Music written for clarinet
As said before, if one does not count the chalumeau as a proper clarinet, the clarinet became popular first during the late 1600's.
Much literature for the clarinet was written during the Romantic period. Because the clarinet was still in its infant stages through the Baroque and much of the Classic periods, it did not become important in literature until the early 19th century. There were many improvements to be made on the clarinet before it could perform the demands that players and composers desired.
By 1740, Vivaldi had written three concerti grossi for two clarinets and two oboes and Handel wrote an overture for two clarinets and corno di caccia in the same decade.
Mozart wrote his Concerto and Quintet for the five keyed clarinet, that appeared around 1778. Beethoven's symphonies were probably played on 5 keyed clarinets until a decade after he died. Ludwig von Beethoven's (1770-1827) early symphonies were often written for clarinet in C, a higher instrument with a tone more like that of the modern E-flat clarinet than of the B-flat clarinet. The clarinets in these symphonies are not used for major solos but rather for harmonic support and do not feature many chromatic passages. It is in the fourth symphony (1806) that the clarinet becomes important in Beethoven's music.
For clarinet literature, Carl Maria von Weber was very important. He wrote many concertos and concertinos, all containing highly difficult and technical passages.
Johannes Brahms (1833-1897) was a very important figure in chamber music for the clarinet in the 19th century. He wrote two sonatas, a trio and a quintet for the clarinet.
Sources: http://hem.passagen.se/eriahl/history.htm, www.klorg.com/adam/history.html, www.geocities.com/prissy1027/history/text.html, www.ocr.woodwind.org/articles/Other%20Authors/ ackerman1.html