The Royal Greenwich Observatory of today is a vastly different institution from that founded in the seventeenth century. An original staff of two housed in one small building has risen to some 250 housed in a number of buildings scattered over more than 300 acres of grounds. Its original, primarily practical purpose of determining longitude at sea has been largely replaced by pure research. If the observatory's history is traced with these various changes in mind, it becomes apparent that the transition period from the early style to the modern occurred during the nineteenth century when Airy was Astronomer Royal.
