The device makers before 1700 haven't mastered this because they did not have thetheoretical and functional background. And therefore the Chalumeau hasn't got an upper register. We still call the lower sign up of the clarinet the chalumeau check in and the upper in reality the center register is termed the "clarinet" sign up. In 1760 the famous and at the moment prime edge Mannheim Orchestra already had the cheap for 2 clarinet avid gamers,both musicians were at a similar time oboe gamers, too. From 1778 on they were clarinet players only. Not long afterthat Mozart wrote his famous works for clarinet adding the concerto for basset clarinet in A generally known as concertofor clarinet in A that are technically extremely challenging. Even with modern-day contraptions they're a problem forprofessional musisicians. At that point clarinets had five technically questionable keys. It is hard to believe that youcould play that music with those gadgets at all, but it should have been feasible, as the critics were excited andyou mustn't ever think that they did not know what first-class in instrument making and gambling was it was the time when stringinstruments like Stradivari violins were built. With every new musical and technical challenge craftsmen and players strived to more suitable the hot and by far not perfect device. This advancement is comparable to biological evolution of living species.