1,104,953. Testing fabrics electrically. FARBWERKE HOECHST A. G. May 12, 1965 [May 12, 1964], No. 20140/65. Heading G1N. In apparatus for testing thin sheets of e.g. paper for resistance to mechanical impact, a sample of the test material is clamped between two rings in a fixed member 10 (Fig. 1) and a striking member 4 is allowed to fall on to it, the force on the striking member is measured by a Piezo-crystal 3, and the stretch of the sample material by a capacitor comprising two fixed plates 11 and a cooperating moving plate 9 attached to the falling member 4. Force and displacement signals are fed to a C. R. O. 12. The test material and its holder 10 are located in a temperature-controlled chamber 7 which is closed except when a photocell arrangement 18, 19 senses the falling member 4 and allows it to enter.