Rapporteur's paper

This Session was to embrace Papers Nos. 7 to 14. Unfortunately, Nos. 7 and 14 have been withdrawn but we have with us the principal Authors of five of the remaining six papers: only the Authors of Paper No. 12 have been unable to attend the Conference.

My comments will be brief in order to leave time for the Authors to show us some slides and give us some vital further information not contained in the printed papers which you all have before you.

The six papers can be conveniently divided into two categories: Class A dealing with measurements of movements and Class B which have involved or were intended to involve failures.