I have two Emil Jardin clarinets. One is all hard rubber, the other has wooden keyed joints, with hard rubber barrel and bell. Both look like they were made by Couesnon.
Bore at top of left hand joint: 14.43mm
Bore at bottom of left hand joint: 14.7
The serial number is very hard to read, only stamped at the bottom of the left hand joint. My best guess is that it is 3560. Only the 3 and 6 are certain. The 0 might be a C.
The main thing that tipped me off that this was a Couesnon product is that both left pinkie keys are unified on one post.
And the pinkie keys are also pin-in-hole type.
This instrument has hard rubber barrel and bell.
The other pieces are not marked with a brand. This shows that this was not one of Couesnon's best models.
I suspect that this was made in the 1930s and no later than the 1940s.
This was testing with a B45 mouthpiece and a Legere Quebec #4 reed. One would appreciate having a shorter barrel to use when needed with this instrument when playing in sharp ensembles.
This is pretty terrific intonation, except for a few sharp notes from low A to D. Remember I play these tests "dumb" and try not to adjust the pitch. And I basically play an F scale, plus a few B naturals. This means that notes like G#s that appear are just harmonic pops. This can be seen in the low number of milliseconds.
I would recommend the Emil Jardin as being appropriate for intermediate to fairly advanced players. The key work is sturdy nickel silver, but not so sturdy as to be appropriate for marching band. The narrow bore makes this a good instrument for chamber music. The narrow bore gives the instrument a quieter, more centered sound, with excellent fluidity when playing large intervals or changing registers.