When was it invented? 1600 the natural horn without valves was used in the royal mounted hunt. It was coiled in a circle to fit over the arm of the riding player. In the 1700's the horn became a regular member in the orchestra. It had "crooks" instead of valves. Valves were invented in 1815 which got rid of the crooks. 1898- Fritz Kruspe combined the F horn and Bb horn to get the double horn.
Where was it invented? In Vienna- a horn in the key of F with crooks. France had piston valved horns. Germany had rotary valves. Fritz Kruspe invented the double horn in Germany.
Who invented it? Fritz Kruspe invented the double horn which combines the key of F and Bb.
What is it made of? Metal, typically brass. Has a nickle or lacquer outside.