there're different models for the 190 tripod.... some could mount horizontally, some can't.
a pic below shows the positioning of the centre column:
http://db.manfrotto.com/product/templates/templates.php3?sectionid=2&itemid=768
a pic below shows the positioning of the centre column:
http://db.manfrotto.com/product/templates/templates.php3?sectionid=2&itemid=768