Internal fastenings for joints

Claim 1

A COUPLING FOR JOINING TWO HOLLOW MEMBERS OF SUBSTANTIALLY TUBULAR FORM, COMPRISING: A FIRST HOLLOW MEMBER OF SUBSTANTIALLY TUBULAR FORM COMPRISED OF A MATERIAL HAVING A GIVEN THERMAL COEFFICIENT AND HAVING A PLANAR SURFACE ADJACENT ITS END; A SECOND HOLLOW MEMBER OF CORRESPONDING SHAPE HAVING A PLANAR SURFACE ADJACENT ITS END FOR MATINGLY ENGAGING THE PLANAR SURFACE OF SAID FIRST MEMBER; MEANS HAVING A DIFFERENT COEFFICIENT OF THERMAL EXPANSION THAN ONE OF SAID MEMBERS AND ARRANGED WITHIN ONE OF SAID MEMBERS AND IN ENGAGEMENT THEREWITH FOR HOLDING SAID TWO PLANAR SURFACES IN MATING ENGAGEMENT IRRESPECTIVE OF TEMPERATURE CHANGES WITHIN THE COUPLING, SAID MEANS COMPRISING A FORCE TRANSMITTING MEMBER SO DISPOSED WITH RESPECT TO SAID PLANAR SURFACES TO APPLY FORCE TO ONE SAID TUBULAR MEMBERS SUBSTANTIALLY IN THE PLANE OF CONTACT OF SAID PLANAR SURFACES IN A DIRECTION TO MAINTAIN SAID SURFACES IN INTIMATE ENGAGEMENT AND A SECOND MEMBER IN ENGAGEMENT WITH SAID FORCE TRANSMITTING MEMBER AND WITH THE OTHER HOLLOW MEMBER ARRANGED TO APPLY AN OPPOSITELY DIRECTED FORCE TO THE OTHER OF SAID TUBULAR MEMBERS ON A PLANE ON THE SAID OTHER TUBULAR MEMBER, SAID PLANE BEING SO LOCATED RELATIVE TO SAID PLANAR SURFACES AND THE THERMAL EXPANSION COEFFICIENT OF SAID FORCE TRANSMITTING MEMBER BEING SUCH THAT ANY CHANGE IN LENGTH IN SAID OTHER TUBULAR MEMBER BETWEEN ITS PLANAR SURFACE AND SAID PLANE IS ACCOMPANIED BY A CORRESPONDING CHANGE IN LENGTH IN SAID FORCE TRANSMITTING MEMBER.