Bb Cornet by Adolphe Sax, 1862
Although Adolphe Sax is mostly known for the invention of the saxophone and secondarily for the Saxhorn family, his factory built just about every sort of instrument that was made in his time. If you have any doubts, the University of Edinburgh Musical Instrument Museums has maintained a list of known examples. This Bb cornet looks somewhat ordinary for the early 1860s in France, even his typically flamboyant braces are toned down here. Sax built most cornets of the Modele Francais (bell and mouthpipe both to the right of the valves) as opposed to the Modele Anglais (bell on the left of valves) that was already much more popular in most of the world. You can read more about this in Niles Eldridge's article on the topic.
This cornet is remarkably well preserved and retains its original Bb and A mouthpipe shanks and mouthpiece. The only work that I've done to it is to remove a crease from the bell and install new corks. I've never cleaned or polished it. It was found in a southern US state, although nothing is known about when it was brought here. The return crook from upper tuning tube to third valve casing had been shortened to raise the pitch from the original French "diapson normal" (A=435) to play in a higher pitch. They didn't get it quite short enough to play in the high pitch used in US bands (about A=452Hz) and it tunes to A=440Hz with the tuning slide pulled out about 5/8". The overall length of this cornet with mouthpiece removed is 13 3/8", the bell rim diameter is 4 7/8" and the bore measures .460".