I've just joined the class rather late (having just bought GPO and then spent some time getting up to a moderate speed on it).
I've got a question arising out of Lesson 2. In the note to Table C (Ranges of the Brass Group), R-K says that the low B natural does not exist on the trombone. I always thought that you could get it in 7th position. Did they just have shorter slides in R-K's day?