This book collects contributions made at a meeting on astronomical instrumentation held at the Royal Greenwich Observatory to mark the seventieth birthday of Robert Hanbury Brown. Twenty-five contributors describe the impact of instrumentation on the advancement of astronomy today. The topics covered include radio interferometry and VLBI; optical interferometry; new technology telescopes; electronic detectors; image processing; and the Hubble Space Telescope. The book is a valuable synthesis of current thought and will be useful to observational astronomers generally.