The river between Oxford and Abingdon in its present shape is a sort of free canal, locked at Iffley and Sandford, and again just above Abingdon. There used to be a lock at Nuneham, but it was taken down. More recently, too, the Folly Bridge Lock was carried away, and has not been replaced. The history of the river as a work of art is a long and interesting one. Obstructions to its natural course, and to its navigation, began with mills and mill-weirs. In early charters there are provisions for removing "gorees, mills, wears, stanks, stakes, and kiddles." Commissions and Acts of Parliament tinkered at the navigation, but till the end of the eighteenth century no progress was made beyond the old mill-weir, with sluices in it to let the boats through. This arrangement was called a "flash" lock. The flashing emptied the reach of the river above the lock, but all the water was needed to move the heavy barge sticking on the "gulls" below. Navigation was of course terribly slow. A bargeman had sometimes to send on ten miles ahead to get a flash when going up stream, and sometimes lay for a month till enough water had accumulated. When he got it there was none for any one else. Leonardo da Vinci, who thought of everything, had invented the pound-lock long ago; and other people before and after him had hit on what seems a very obvious contrivance. But that ingenious people, the Chinese, are said still to hoist their barges over weirs, and it was not till the time of the great period of canal-making that began with the Bridgewater Canal in 1760 that the pound-lock made any way in this country. The canal from Birmingham reached Oxford in 1790, and shortly afterwards the locks and towpath were put into their present shape. Then followed jealousies between rivers and canals, till the railways came and made inland navigation of less importance. Nowadays there is little barge traffic through Oxford (Folly Bridge was always a difficult point), but another question, that of floods, presses as much as ever. Quite recently the engineer to the Thames Commission brought out a scheme for doing away with Iffley Lock and Weir, and dredging a deep and narrow channel between Iffley and Folly Bridge. The Vice-Chancellor and the Dean of Christchurch, both by virtue of office Commissioners, were in favour of this scheme with a view to Oxford health; but it has been proved to the satisfaction of the Thames Conservancy Board, whose officers have examined the place, that so sweeping a change is not needed. The effect of the change would be to give the river banks instead of brims, and it has been argued that it would kill the elms of Christ Church and the fritillaries in the water meadows about Iffley. Most serious of all would be the loss of Iffley Mill. We may hope that Oxford health need not be bought so dearly. [Illustration: OXFORD TO ABINGDON.]