The modern practice of lining the walls of our rooms with book-shelves, though in one sense a reversion to an ancient type, in another is a definite change of system, of which examples are found in the sixteenth century abroad, but the first in England is in the Bodleian. In the Old Reading Room Sir Thomas Bodley reproduced the stall system. But when in his last days he erected an additional room (the Arts End) his choice fell on the newer idea that a wide space should be left in the middle of the room, and the books be all placed against the walls (1613). The lower books (folios) were still chained, and could only be used at the desks attached; such was the case, for instance, with the First Folio of Shakespeare, marked S. 2.17 Art. (see p. 46). The Gallery books were quartos and octavos, not chained, and given out to readers below by one of the officers of the Library. This arrangement was imitated in the Selden End, which was completed in 1640. [Sidenote: Kinds of Libraries.] So far an attempt has been made to sketch briefly the evolution of a library in ancient and mediæval times. The plan of the present chapter of generalities now requires that we should consider the kinds of modern library, and the position which the Bodleian holds among them. There are libraries and libraries. There are libraries of Reference or, as they are sometimes termed, Deposit; and there are libraries of the second rank, adapted for local and popular use. These two kinds are typical, and fall apart, as will be seen, by the application of a simple test.