I mean, it seemed like a good idea at the time…
It basically an Ophicleide
From the wikipedia article:
The ophicleide was eventually succeeded by the tuba and euphonium through careful and deliberate marketing, although it remained popular in Italy until the early twentieth century. One of the last great ophicleide players was the English musician Sam Hughes. The instrument has also been considered a direct ancestor of the saxophone: anecdotally,Adolphe Sax, while repairing an ophicleide, put a woodwind mouthpiece on the instrument and liked the sound, leading to the saxophone’s later creation; however, this story is not considered plausible, since the developmental history of the saxophone is well documented, and the ophicleide and saxophone are only superficially similar to each other—in particular their wide conical bore, and large tone holes.