  We estimate the strength and range of forces mediated by string moduli in
type I string models with two (or more) large internal dimensions. We find that
forces mediated by twisted moduli which live on the brane world--volume can
mediate forces which are orders of magnitude stronger than gravity with a range
up to a milimeter. If they exist, these forces can be easily observed in
present experiments. On the other hand, forces mediated by the dilaton and
untwisted moduli are about a hundred times stronger than gravity and may be
observed depending on their range.
