Why is the bell on a trumpet called a bell?

It resembles a Bell. It"s a traditional name. Look a Diving Bell is not necessarily Bell-Shaped. the ones I was on ( as amusement rides_ were cylindrical, with a hatch on the side. (Coney Island). Still called Diving Bells/. so it"s a tradition. Bell is not an intrument house (Like Selmer- who do make Trumpets)so it is not a patronymic like the Bell Telephone company ( Alexander Graham Bell- Inventor and founder= and the name of my aunt"s cat- aunt is retired from the Phone companyl.