At first, there were four types of trombones soprano, bass, tenor, and alto. At some period in the 19th century, trombones were constructed with valves similar to most brass instruments but this was short lived. It has a major difference from other brass instruments the trombone sounds exactly as how it is written. Sound waves are created coming from the back and front panels as the soundboard is vibrating. The sound box serves as a resonant cavity and reflects the sound waves produced. The sound volume increases greatly compared to the primary volume created by the strings. Some sound is then projected out of the hole. It is a cylinder-shaped tube with usually a single reed. It has at least two parts and has a sliding joint or bridle which manipulates the pitch. Construction A constant air supply is provided by the bagpipe s construction. The air flow could be maintained in the chanter and drone pipes through using the left hand to squeeze the bag during breathing periods. The plectrum banjo is just like the regular banjo but it does not have a short drone string. It is typically played with a pick similar to that of the guitar. The tenor banjo has a shorter neck than the plectrum banjo. It became popular and had seventeen frets and a length of nineteen to twenty-one inches around 1910. It elevated its status in the orchestra during the 18th century wherein orchestral and major solo music was made for it. Bassoons for military bands, tenoroons, and sub contrabassoons were created in the 19th century. It was released from the curse of playing the continuo part. Nowadays, it is played in opera, symphony orchestra, and in contemporary musicals. Originally, bugles had a coil-shape alike with the French horn and were for communication in hunts and for announcements. Based on its use, it is considered to be like the horn of modern automobiles. Based on recorded history, bugles were used by officers in the cavalry to instruct soldiers when in battle.