The chains are made of links of hammered iron as shewn in the sketch (fig. 78) which represents a piece of one of the actual size. There is usually a swivel in the centre, probably to prevent twisting. They vary somewhat in length, and in the length of the links, according to the shelf on which the books to which they belong are ranged, it being obviously necessary to provide for the convenient placing of a book on the desk when a reader wished to consult it. The most usual dimensions are 3 ft. 4 in., 3 ft. 6 in., 4 ft. 3 in. The removal of any of the volumes, or the addition of a new one, must have been a tedious and inconvenient operation. The bar would have to be withdrawn, and all the rings set free. Moreover, if this change had to be effected in one of the compartments remote from the end of the case which carried the lock, the bar belonging to each of the other compartments would have to be withdrawn before the required volume could be reached. [Illustration: Fig. 78. Piece of chain, shewing the swivel: Hereford. Actual size.] If the views (figs. 70, 71) of the book-cases at Corpus Christi College, Oxford, be attentively examined, it will be seen that the ironwork exactly resembles that at Hereford. We find similar sockets to contain the bars at the junction of the horizontal shelves and vertical uprights, and a similar system of iron hasps to prevent the bars from being withdrawn. The desk for the reader would of course vary according to individual taste. As a general rule it was attached to the ends of the case by strong hinges, so that it could be turned up and got out of the way when any alteration in the ironwork had to be carried out. Iron hooks to hold it up were not unfrequently provided. One of these, from the Bodleian Library, is here figured (fig. 79). It was also usual to provide a slit in this desk, about 2 in. wide, as close as possible to the shelf, for the chain attached to the book in use to pass through. This is well shewn in the view of a single book-case in Merton College, Oxford (fig. 83). I will next describe the library of Merton College, Oxford. There is still considerable doubt respecting the date of some of the bookcases, but the appearance of the library is so venerable, so unlike any similar room with which I am acquainted, that it must always command admiration, and deserve study[335]. [Illustration: Fig. 80. Exterior of the Library at Merton College, Oxford, as seen from 'Mob Quadrangle.' From a photograph by H. W. Taunt, 1899.] The library occupies the whole of the first floor of the south side of "Mob Quadrangle" and the greater part of the same floor of the west side (fig. 80). It is entered through a doorway in the south-western angle of the court, whence a staircase leads up to the vestibule (fig. 81). This room is separated from the two divisions of the library by lofty oak screens, elaborately carved and ornamented in the style of the early renaissance.