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I have looked at this piece a bit, and as far as I can remember, there is no written bass clef for the horn. Maybe I misunderstood your exact question, but there is no bass clef anywhere in the horn part.

The horn part spans the range of a concert F at the bottom of the bass clef to a Eb at the top of the treble clef.

And to politely correct Chris, the horn part reaches the bass clef only once in the piece for about a bar. The second half of bar 40 and bar 41 of the fifth movement are in bass clef. That appears to be the only time the horn goes into bass clef.