(19)

(11)

EP 0 216 768 A1

(12)

(43) Date of publication: 08.04.1987 Bulletin 1987/15 (21) Application number: 85902599.0 (22) Date of filing: 31.05.1985

(51) International Patent Classification (IPC):  G01R 29/ 10( . ) (86) International application number: PCT/GB1985/000231 (87) International publication number: WO 1985/005692 (19.12.1985 Gazette 1985/27)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 31.05.1984 GB 19840013928 (71) Applicant: H.R. SMITH (TECHNICAL DEVELOPMENTS) LIMITED Witney, Oxfordshire, 0X8 5TF (GB)	(72) Inventor: HILL, David, Roy Herefordshire HR6 9QA (GB)