Phillip Otto Euler's workshop in Frankfurt flourished from 1810 onward.  Following his death in 1834, his son August Anton Euler continued to make instruments with the same stamp, disbanding the workshop in 1873.  Clarinets by Euler show characteristic design features of early romantic instruments including multiple keys to provide players with alternative fingerings to the basic five-key scale, larger tone holes to improve response and volume, and ergonomically fitted LH pinkie keys with the addition of rollers to facilitate a quick slide between B-natural and C#.  As with many of the earlier romantic instruments, the clarinets from the Euler workshop mounted keys in blocks rather than posts and saddles, a feature used on later instruments.  Surviving instruments from the Euler workshop made after 1834 continued to mount keys in blocks, though the RH Eb and low F keys were moved into more acoustically perfect positions which warranted the use of post-mounted keys. 

Instrument Specifics
Key: C (Pitch A430-440, depending on the mouthpiece)
Materials: Boxwood, Ivory, Brass
Key Mechanism: 13-key (basic 12, 13th key is a side key for Eb/Bb for LH 1)

This instrument is notable for not only the high quality of boxwood (note the flaming in the lower joint), but the artistry with which the keys are mounted into the wood.  The mechanism moves freely and all of the pads seal tightly over the tone holes.  The tone holes on this instrument are countersunk, an early 19th century feature that produced a raised tone hole edge allowing for a more accurate seat for the pad.  The intonation on this instrument is relatively stable, though a previous owner inserted a metal tube into the A key tone hole, meaning that the throat A and Bb play slightly lower than they should.  The sound quality is bright, but with a full resonance, making this an ideal instrument for music from the 19th century.