try http://www.ee.surrey.ac.uk/Contrib/manx/history/legs.htm
the motto comes from a pun first found on the 1668 penny (and I believe intended to say that the coin would pass any test) - however as the Manx were well attached to their pennies the motto (which circled the legs + like many entries on today's bulletin boards was also misspelled!) has ever since always gone along for the ride.