There were few standards for simple system flutes in the 19th century. Still, it is possible to select some configurations and call them 'standard'. For more discussion of the variety of keys, see the pages on Classical Flutes and 19C Simple System Flutes, I.
We illustrate with a 5-key French flute (keys for C, Bb,G#,F,D#), an 8-key American flute (C, Bb, G#, two keys for F, D#, low C#, low C) and an 11-key German flute (C, two keys for Bb, G#, two keys for F, D#, low C#, low C, low B, and a trill key for the high e'''/d''' trill).
A type of instrument very common in France throughout the entire 19th century was the five-key flute. Part of an instrument stamped Tulou / Paris (c.1835) is shown below. There is exactly one key for each note outside the D major scale: D#, F, G#, Bb, C.
The note names are placed close to the touch of the key, not the hole the key controls.
The most common form of the eight-key flute is shown below. This is part of a flute stamped E. Riley / New York (c.1830). The keys beyond the five above include a second key for F with a touch for LH4 and two keys, for c' and c'#, on an extended foot joint. The second F key became known as the long F key. The C and C# in the photo below are placed next to the holes controlled by the two keys rather than the touches (for RH4).
A common form of the German and Viennese flute in the second half of the 19th century had eleven keys. Shown is a section of a flute stamped W. Liebel / Dresden (c.1850). There are three keys for LH4 and three keys for RH1.
The keys for LH4 are the G# and long F keys, as on the eight-key flute, and a touch for a long key for low B. The four section construction of the five-key and eight-key flute (counting the head joint as one section, whether or not it had a tuning barrel) was usually abandoned for a three section design (joining the lower center and the foot joint) so that this low B key could be more securely mounted.
The keys for RH1 included the C key of the five and eight-key flute, a second key (or lever) for Bb, and a long key that opened a hole far up on the body, close to the head joint. This latter key was used soley for the trill on high d''' with e'''.