The windings of the river through the great level which it flows through, after passing Oxford, are frequent ; but the general direction of its course is to the south, with a small inclination to the east, as it passes the Berkshire hills, and the town of Dorchester in Oxford shire. A short distance below this place it is joined by the Thame. This river takes its rise from several small streams, some of which descend from the central parts of Buckinghamshire, others from the borders of Hert fordshire, and many from the lower parts of Oxford shire.
After the junction of the Isis and the Thame, this ri ver obtains its proper name, being originally called Thame-isis from this circumstance. From Wallingford to Pangbourn the inclination of the stream is almost due south; at the latter place it begins to form a considera ble circle by the east to the north, below Reading, till it reaches Henly; after passing this latter place it inclines by the north-east to the south again, to approach Maid enhead; hence it winds in various directions, but gen erally south-east, till it passes Mudson and Staines. It there forms a vast circle by the south to the east, till it reaches Brentford; after which as it approaches London, its direction is, for the most part, to the north-east. In the vicinity of the metropolis it turns with a bold swell to the east : this direction it preserves, though occasion ally varied by broad reaches, as they are called, till it falls into the sea.
In its passage the Thames receives no fewer than six considerable rivers that are not navigable, and eleven that are. Its course has been computed about 160 miles, of which it is navigable above 130 from its mouth. As far as Deptford it is navigable for vessels of almost any burden ; to the pool for vessels of 400 tons; to London Bridge for those of 200. The tides flow up to nearly the distance of 80 miles from its mouth. The fall of water from Oxford to Maidenhead is about 25 feet in every ten miles ; from Maidenhead to Chertsey 22 feet in the same distance ; from Chertsey bridge to Mortlake 16 feet ; from Mortlake to London about one foot per mile. Afterwards the fall diminishes more gradually, till the river unites with the sea.
The Thames is one of those rivers which rather de rive their character from the country through which they flow, than impress their own character by their boldness and rapidity on the tract they pursue. It passes through some of the most beautiful, as well as the most fertile districts of the kingdom; but even where the country through which it flows is hilly, it never can be called a rapid stream; it is not, however, sluggish, but is more distinguishable for its majesty, and the purity of its wa ters, which generally fill its verdant banks, and are sel dom discoloured by mud, except after great floods.
When these occur, the whole country in the level parts of its tract appears like a sea; but the mischief which it thus occasioned, is much less than that produced by smaller and more rapid streams, when they overflow their banks. The part of its course most distinguished for romantic scenery or picturesque beauty, is that which stretches from Wallingford to Reading, 1 enley, Marlow, and Maidenhead bridge. About Henley in particular it sweeps through a rich and highly beautiful country, to which it adds a majestic and imposing feature; its valleys in this part of its course arc bounded by hills richly clothed with beechwood, and finely embellished by the seats of many of the principal of the English nobility. Vast plains succeed, in which the Thames constitutes the chief feature. As it approaches London, its cha racter changes, and the richness of nature gives place to evidences of the power, the wealth, and the skill of man. Mighty works of art adorn its banks, which abound in populous towns and villages. At London it is a superb tide river, " full of vessels of every descrip tion, which arrest the eye strongly in the bold sweeps it afterwards makes, through increasing marshes to the sea, and to the end it preserves that air of placid dignity and imposing consequence, which distinguish so eminently this monarch of the British rivers." The Severn, the second commercial river in the king dom, has its principal source in a small lake on the east ern side of Plinlimmon, not far from the head of the Wye. At first it bears the name of the Hafren river, the name by which, through its whole course, it was known to the Britons. From this source it flows towards the south-east, and afterwards turns to the northeast, as it approaches Newtown, where it takes its proper. name of Severn. Hence, through the delightful vale of .Montgomery, its course is almost clue north, till, enter ing the great plain of Shropshire beyond Welshpool, it turns abruptly to the south-east. Afterwards pursuing the same direction, it almost encircles the town of Shrewsbury. Flowing through the celebrated Colebroke dale, and passing Bridgnorth, it pursues a southerly course, as it leaves the county of Salop, and enters Worcestershire, at Bewdley. Here it again, a little lower, becomes a commercial river, being joined by those numerous canals which bear all the trade of Birming ham, Kidderminster, and the other manufacturing towns of Warwickshire, Staffordshire, and 'Worcestershire.