The French Horn
The French horn, commonly known as "the horn", is made from more than 6 meters of brass tubing wrapped into a coil with a flared bell, and is in common use in many orchestras and ensembles. Another name for the French horn is the double horn (because it can be played in F and B♭). Three rotary valves control the flow of air whilst a fourth valve, operated by the thumb, routes the air to either the F tubing or the B♭ tubing.
As with all brass instruments pitch is controlled through the adjustment of lip tension (embouchure) in the mouthpiece and the operation of valves, played with the left hand, to route the air into extra tubing. The backward facing bell helps to create a more subdued sound most associated with the French horn which is in contrast to the bright, penetrating quality of the trumpet. The pitch of the notes can also be controlled by the position of the hand inside the bell (which effectively reduces the diameter of the bell), so the pitch of any note can be easily raised or lowered based on the position of the hand.
The French horn is the third highest sounding instrument in the brass family group and sits below the trumpet.
The flugelhorn is a brass instrument that resembles a trumpet but has a wider conical bore. The flugelhorn is built in the same B♭ pitch as many trumpets and cornets and commonly employ piston valves with the same fingering system as other brass instruments. It is often adopted by trumpet players as a "second instrument" and is usually played with a deeper conical mouthpiece than either trumpets or cornets to produce tone that is more mellow, though some adaptation to the playing style may be needed to master the flugelhorn.
Jazz music, brass band music, and popular music, will often include the flugelhorn whereas orchestral music will feature the flugelhorn occasionally.