The Evolution of French Horn
The modern orchestral brass French horn was an invention based on early hunting horns. Horns were first used as musical instruments during 16th century operas. During the 17th century, modifications to the bell end (larger and flared bells) of the horn were made and the cor de chasse, or French horn as the English called it was born.The first horns were monotone instruments. In 1753, a German musician called Hampel invented the means of applying movable slides (crooks) of various length that changed the key of the horn.
In the 19th century, valves instead of crooks were used, giving birth to the modern French Horn and eventually the double French Horn
There are different kinds of horns , there is
the common double horn
vienna horn
hunting horn
omnitonic horn
natural horn
mozart era natural horn
hunting horn in E♭,
In the 19th century, valves instead of crooks were used, giving birth to the modern French Horn and eventually the double French Horn
There are different kinds of horns , there is
the common double horn
vienna horn
hunting horn
omnitonic horn
natural horn
mozart era natural horn
hunting horn in E♭,
The Common Single Horn and The Double Horn

This is a single F Horn. We can tell because of the three valves (keys) and the three "buttons" (valve caps). Notice there is only one layer of tubing that corresponds to these valves.

This is a Double French Horn. It has four valves, (the fourth valve/valve cap is right along the left side of the image.) But that's not enough to distinguish it as a double. A single French horn in B flat will also have four valves just like this. We know it's a double because it has a double layer of tubing extending from the valves. If you look closely, you will see the second, smaller layer of tubing lying beneath the top layer. The reason a double French Horn is called a double French Horn is because it is actually two horns in one - a Single F Horn and a Single B flat horn combined into one instrument, hence, a double horn.
This is the Siegfried's Horn Call by Wagner.One of the best horn solos I've ever heard.
The Vienna Horn

During the nineteenth century, a number of experiments were made in adding valves to the natural horn to enable it to play chromatically without the need for hand-stopping. These experiments included adding piston valves (as used in modern trumpets) to a single F horn. The horn was still crooked, by inserting other tubing, to re-tune the instrument for music written in base keys other than F.
These are the amazing Vienna Horns playing Jurassic Park.
The Hunting Horn

Horns were often used during hunting. These early brass instruments were round so that the hunter could put his arm through it and carry it on his shoulder and blow it while riding a horse. The riders could send messages to one another by blowing particular notes
Natural Horn

The natural horn is a musical instrument that is the ancestor of the modern-day horn, and is differentiated by its lack of valves. It consists of a mouthpiece, some long coiled tubing, and a large flared bell. Pitch changes are made through a few techniques. It depends on hand stopping and lip tension.
Mozart Erza Natural Horn

The Horn Concertos by Wolfgang Amadeus Mozart were written for his friend Joseph Leutgeb whom he had known since childhood. Leutgeb was clearly a skilled player, as the works are very difficult to perform on the natural horn of the period, requiring lip trills, much hand-stopping, and rapid tonguing.