Sandy, a transposing instrument is one that doesn't play the notes as written. That is, when you see a "C" written, you finger it like a "C" but, a different note, say a "G" comes out, and all the other notes are offset by the same amount--a "D" will produce an "A", and so on. It has the great advantage that all instruments of the family are fingered the same. So if something is written with no accidentals, you just play it that way. If the instrument was really in "G" the "F#" would be "built in". If you play something with no accidentals that is written for an instrument that doesn't transpose, you will be playing in G while everyone else is playing in C. To play in tune with everyone else you would have to move up a fourth and mentally add a flat to B--not easy with a snappy jig. (I wouldn't even like to do it with the Dead March from Saul.)

As far as I know it is only the single reed and the horn family instruments that transpose. Although, someone told me classical guitar music is written an octave higher than is played.

Jon, I haven't reached the stage of having callouses on my fingers. The area that is sore at the moment interferes with fingering the recorder, and with my touch on the clavichord (probably the only keyboard that is highly sensitive to touch,) so I assumed the callouses would do the same. I suppose the soreness tends to spread over a larger area than where the callouses will be.

Murray