The Heritage concerning ancient musical instrument is very reduce. Even less if we consider public collections. France was a leading country in that field. But the collections were mainly preserved with few respect. Since two generations, with care for education and revival of ancient music, a lot of historical instruments were put back in playing order, while many interventions let often sources of knowledge lost for the future. Today the policy is more respectful, less operative, caring for a scientific knowledge of materials, structures, but also accessories having an essential effect on the sound production : i.e. strings, fittings, linings, or surface treatments, all elements usually destroyed and today studied, referenced, even reproduced identical in partial or whole facsimile. After giving a kind of assessments, the burning question is : how many specimens, with “ authentic ” acoustical specifications, shall we let to future generations ? And what are studying acousticians when they compare without critical organological analysis a so called « Stradivarius violin » with a modern one ?