Photographs show instruments and equipment in use by staff and students in the Department of Electrical Engineering, University of Sydney. Precision instrument shop of the Mathematical Instruments Section, Commonwealth Scientific and Industrial Research Organization, attached to the Department of Electrical Engineering, University of Sydney -- Testing a transmitter for exploring the upper atmosphere (ionosphere) -- Part of the Fourth Year Power Laboratory in the Department of Electrical Engineering, University of Sydney -- (2 photographs) -- Control unit of Differential Analyser -- Rear view of control cabinet for Differential Analyser -- A speech transmitter for communication with field stations at Camden and Blaxland when making adjustments to equipment used in investigation of the ionosphere.