Hey Skiff....If you looked at the pictures and read the stuff you probably have a good idea, but let me mention a couple of things not quite obvious.

The French Horn and Mellophone use different mouthpieces and valves. The Mellophone uses a cup style mouthpiece as do most other brass instruments and uses piston style valves. The French Horn uses a conical mouthpiece and rotary valves.

Contrary to the article, the mellophone does not sound much like a French Horn....a little, but not much. The primary use is to supply an instrument in the same register/voicing to do the Horn parts in Marching bands. Most marching bands shunned them in favor of the alto horn (altonium). The Alto Horn looks like a small, bell front, baritone horn. The Ohio State Marching Band for many years used alto horns and replced the trombones with Tromboniums which fits between the baritone and the alto horns and replaces the trombone voicing. What this did was get rid of the trombones where slides were all carried at different levels and kinda' ruined the "precision" look. They went to trombones again awhile back when they made some major changes in the band (like allowing women and adding woodwinds and doubling the size (it was 120 men, all brass and drums).

Spaw