Profile: Wexham Developments supplies and manufactures test equipment for the construction industry. The demountable mechanical strain gauge ( DEMEC ) was developed at the cement and concrete association, for measuring strains in concrete structures. It consists of a standard or a digital dial gauge mounted on an Invar bar. A fixed conical point is mounted at one end of the bar, and a moving conical point is mounted on a knife edge pivot at the opposite end. The pivoting movement of this second conical point is measured by the dial gauge. The gauge has been designed so that only minor temperature corrections are required for changes in ambient temperature, and an Invar reference bar is provided for this purpose. A range of gauge lengths are available from 100 mm upwards.