On the Ouse (York), below Naburn Lock, the conservators find it difficult to keep the channel at its proper depth by reason of the great deposits of floating sand, or "warp," distributed by the tides, the scour of the river being insufficient to carry the warp out to sea. Vessels are at times unable to navigate for several days, obstructive shoals are formed, and the line of the channel is frequently altered.

On the Bedford Ouse the traffic on the upper parts of the river has come to an end, and, though there is still a small amount between Lynn and St. Ives, "the river is in many places very shallow and choked with weeds and mud, so that barges are often stopped for days, and the use of steam traction, up to St. Ives, is impossible."

The Nen from Northampton to Wisbech is "navigable with difficulty"—where the water is sufficient at all—by barges of the smallest size; but sometimes navigation even by these barges is impracticable for weeks together in certain parts of the river. Between Northampton and Peterborough the course of the Nen is extremely tortuous. "It would," says the report, "take a barge nearly three days to travel the sixty-one miles by water, while the railway can carry goods from Northampton to Peterborough in two hours."

It is thus evident that rivers, whether navigable naturally or rendered so by art, must be regarded as water highways possessed of considerable disadvantages and drawbacks in respect to inland traffic when they are on the scale and of the type found in England. Dependent on the forces of Nature—ever active and ever changing—rivers must needs be the exact opposite of the fixed and constant railway line unless those forces can be effectually controlled under conditions physically practicable and not too costly. "Rivers," says L. F. Vernon-Harcourt, in his book on "Rivers and Canals," "are not always suitable for navigation, in their natural condition, even in the lower portions of their course; and, owing to the continual changes taking place in their channels and at their outlets, they are liable to deteriorate if left to themselves." Left to themselves the English rivers, like the Roman and the British roads, were for a thousand years after the departure of the Romans, and the liability to deteriorate may well have shown itself during this period, before even the earliest of the River Improvement Acts was passed; though the deterioration due to the ceaseless operations of Nature may obviously continue in spite of all Acts of Parliament, and notwithstanding a great expenditure of money.

The fate that has overtaken so many English rivers which once counted as highways of commerce may be compared with the fate that, also through the operation mainly of natural causes, has overtaken many of our once flourishing sea ports.

When, in the thirteenth century, Liverpool was raised to the rank of a free borough, there were between thirty and forty places which, whether situated on the coast or some distance inland (as in the case of York), were counted as seaports. Their order of importance at that time is shown by the following table (taken from Baines's "History of Liverpool"), which gives the taxation then levied on each; though the amounts stated should be multiplied by fifteen to ascertain their equivalent in the money of to-day:—

£00s.00d.£00s.00d.
London836012010Seaford12012002
Boston788015003Shoreham20004009
Southampton712003007Chichester23006000
Lincoln656012002Exmouth14006006
Lynn651011011Dartmouth03000006
Hull344014007Esse07004008
York175008010Fowey48015011
Dunwich104009000Pevensey16017010
Grimsby091015001Coton000011011
Yarmouth054016006Whitby000004000
Ipswich060008004Scarborough22014000
Colchester016008000Selby17011008
Sandwich016000000Barton33011002
Dover032006001Hedon18015009
Rye010013005Norwich06019010
Winchelsea062002004Orford11007000

Of these ports the majority have ceased to be available for the purposes of foreign commerce. Dunwich, once a considerable town, the seat of a bishopric, and the metropolis of East Anglia, had its harbour and its royal and episcopal palaces swept away by encroachments of the sea. Hedon, in the East Riding of Yorkshire, returned two members of Parliament in the reign of Edward I., and was a more important centre of trade and commerce than Hull; but its harbour, getting choked up by sand, was converted into a luxuriant meadow, and the ports of Hull and Grimsby now reign in its stead. Sandwich, Romney, Hythe, all the Cinque ports except Dover, and various other ports, got choked up with sand, while others that have been able to retain a certain amount of traffic are to-day only the ghosts of their former selves.

It is certain that in the case of English navigable rivers of any type, much might require to be done, and spent, in order to keep navigation open. With most of them it was a matter of carrying on an unceasing warfare with elemental conditions. Patriotic men like Sandys, Mathew and Yarranton might bring forward their schemes, companies might raise and spend much money on river navigation, and municipal corporations might do what they could, within the range of their means and powers; but the inherent defects and limitations of the navigation itself were not always to be overcome by any practical combination of patriotism, enterprise and generous expenditure even when—and this was far from being always the case—the requisite funds were actually available.

Vernon-Harcourt is of opinion that "the regulation, improvement and control of rivers constitute one of the most important, and, at the same time, one of the most difficult, branches of civil engineering"; and this difficulty must have been found still greater in the last half of the seventeenth and the first half of the eighteenth centuries, when river improvement was engaging so much attention, but when civil engineering was far less advanced than is the case to-day.