This is a Couesnon Cornet, made in 1920. As the cornet that started my collection of vintage brass was a Couesnon, this brand has my special interest and I have several in my collection. This looks like a Série SO No. 4 A model, the basic student model upgraded with a double water key. It was in playable condition, although the main tuning slide was stuck. When I tried to loosen the slide, I accidentally warped it beyond repair...RIP.