9 Signal Measurement, Electrical, Testing and Scientific, Instruments and Equipment, and Apparatus for Measurement of Signals and for Controlling Brakes Especially Intended for Utilization in the Aerospace Industry-Namely, Batteries, Storage Capacitors and Condensers, Electro-Valves and Servo-Valves, Oscillation Reducing Units for Suspensions and Stabilizers, Circuitry for Brakes and Brake Controls