For the first century of its existence, the lives of its Astronomers Royal formed practically the history of the Royal Observatory. During this period, the Observatory was itself so small that the Astronomer Royal, with a single assistant, sufficed for the entire work. Everything, therefore, depended upon the ability, energy, and character of the actual director. There was no large organized staff, established routine, or official tradition, to keep the institution moving on certain lines, irrespective of the personal qualities of the chief. It was specially fortunate, therefore, that the first four Astronomers Royal, Flamsteed, Halley, Bradley, and Maskelyne (for Bliss, the immediate successor of Bradley, reigned for so short a time that he may be practically left out of the count), were all men of the most conspicuous ability. It will be convenient to divide the history of the first seven Astronomers Royal into three sections. In the first, we have the founder, John Flamsteed, a pathetic and interesting figure, whom we seem to know with especial clearness, from the fulness of the memorials which he has left to us. He was succeeded by the man who was, indeed, best fitted to succeed him, but whom he most hated. The second to the sixth Astronomers Royal formed what we might almost speak of as a dynasty, each in turn nominating his successor, who had entered into more or less close connection with the Observatory during the lifetime of the previous director; and the lives of these five may well form the second section. The line was interrupted after the resignation of the sixth Astronomer Royal, and the third section will be devoted to the seventh director, Airy, under whom the Observatory entered upon its modern period of expansion. 'God suffers not man to be idle, although he swim in the midst of delights; for when He had placed His own image (Adam) in a paradise so replenished (of His goodness) with varieties of all things, conducing as well to his pleasure as sustenance, that the earth produced of itself things convenient for both,--He yet (to keep him out of idleness) commands him to till, prune, and dress his pleasant, verdant habitation; and to add (if it might be) some lustre, grace, or conveniency to that place, which, as well as he, derived its original from his Creator.' In these words JOHN FLAMSTEED begins the first of several autobiographies which he has handed down to us; this particular one being written before he attained his majority, 'to keep myself from idleness and to recreate myself.'