The Swale is formed principally of two streams, which, risini respectively near two hills called the Lady's Pillar and Shunnoi Fell, flow in an easterly direction along the opposite sides of the hie ground called the Water Crag, which has an elevation of 2180 feet until, the first-mentioned and principal branoh having turned to the south, after flowing through the valley called Swede-Dale, they unite at 3luker. From 3luker the river has an Irregular course towards the east past Reeth to Richmond, below which its course inclines some• what to the south, and it receives, together with several minor streams, the river Oilling on the left side. Not far from Northallerton it receives on the right the Bedalebeck, or Bedale River ; and farther south, in the latitude of Thirsk, it is joined on the left by the Wiske, a stream which rises near Osmotherley, on the west escarpment of the Eastern Moorlands. From this point the course of the Swale, though very tortuous, continues In a south-south-east direction to its junction with the Ure, receiving in its course on the left side two considerable streams which descend from the Ifambleton Hills, on the escarpment of the Eastern Moorlands, the northern and most important of which flows by Thirds, aid is called the Codbeck.
The Nidd rises about 3 miles N.E. from Kettlewell, on the adjacent mountains called the Orient Wharnside and Black Fell, and after flowing eastward to Bleasflcld Scar, It enters the earth by a wide and rocky cavern called Goydon-Pot-Ilole. It reappears about two miles south of that point by two issues, the streams of which shortly unite, and then, after receiving the Stone, a little river which rises in Nether dale Forest, very near the source of the Nidd itself, the river takes a tolerably direct course towards the south-east to Pateley Bridge. It then inclines more to the east, and descends along the slope of the Western Moorlands, by Ripley and Knaresborough to Colthorpe, whence its g neral derectIon is north-east to the Owe at Nun Monkton.
The Muerte, the next tributary on the same side of the river Ouse, and which is one of the most beantiful streams in the Wand, rises also in the Western Moorlands, very near the source of the Ribble.
The main stream, rising about three miles north of the Pennigant Mountain, flows eastward through Langster-dale or Langstrath-dale to Buckden, very near the border of the North Riding, where it turns nearly due south along Kettledale. passing Kettlewell, near which place it receives a oonsiderable tributary. After pursuing the same direction to Orassington the river becomes very tortuous, bnt inclines generally to the south-east, by Barden Tower and Bolton Abbey, where it forms the main feature of several miles of scenery of sur passing beauty. A short distance below Barden Tower the stream rushes with great impetuosity through a narrow passage in the rocks, and forms a remarkably picturesque object. This chasm, known as the 'Strid,' Is only about six feet wide. It Is the scene of a legend which forms the subject of poems by Wordsworth and Rogers. One of the small tributaries of the Wharfe forms a picturesque waterfall in Bolton Park, not far from the Strid. From Bolton Abbey the Wharfs, flows south-east to Ilkley, near Rommell's Moor, whence it turns east by Otley and Harewood to Wetherby. From Wetherby the Wharfe inclines more to tho south-east, and passing by Tadcaster, up to which place it is navigable, joins the Ouse at Nun-Appleton, a little above Cawood.
The source of the Aire, Air, or Are, is in Malham Tarn or Water, 5 or 6 miles E. by N. from the town of Settle, in the district of Craven, among the Western Moorlands; but for about a mile south from this lake the stream rune uuderground, and reappears at the base of a perpendicular rock 286 feet high, which forms the centre of a romantic amphitheatre of limestone reeka called Malham Cove.' The course of the Aire, and of those subsidiary streams which unite with it in the upper part of its course, is generally towards the south for a few miles, until near Gargrave it is crossed by the Leeds and Liverpool Canal, which passes over it by a largo aqueduct at an elevatiou of about 414 feet from the sea at low water, and which from that point follows the valley of the Aire to Leeds, and the levels of which, here after noticed, will give some idea of the descent of the valley. From Gargrave the general course of the river is south-east, passing to the southwest of Skipton, Rumbold's or Rommell's Moor, and Bingley, east of Keighley, and north of Bradford, along the picturesque valley of Airedale, to Leeds, passing in its course the ruins of Kirkstall Abbey.
At Leeds the canal terminates, the river itself being made uavigable below that town. It proceeds in the same direction from that town to Castleford, where it receives the Calder from the west, and from which point it pursues a very irregular course, the main direction of which is nearly due east, but inclining a little to the south, by Knot tingley, Ferrybridge, and Kcllingtou, to Snaith, a little below which town it receives the Don from the south, and from this junction it runs east by north for 5 or 6 miles (direct distance) to its junction with the Ouse at Assleby Island, near Armin, or Airmin, a little to the south-west of Bowden. Tho improvement of the Aire, with its important tributary the Calder, for the purposes of navigation, forms an important feature in the history of this class of improvements, these rivers having been made navigable under the powers of an Act passed in 1699 (10 and 11 Will. III., c. 19), upwards of half a century prior to the date of any enactment for a canal navigation. As before intimated, the Aire is not navigable above Leeds; but under the powers of the Act referred to, the navigation was formed from that town to the junction with the Calder, a distance of 111 miles, in which there is a fall of 431 feet, effected by six locks, and also from the junction of the two rivers to Weeland, a farther distance of 181 miles, with a fall of 344 feet, by four locks, making a total uavi ;able length of about 30 miles, with which several short connections save been formed by private canals and railroads extending to quarries and collieries in the viciuity. [CALDER Riven.] The Don, or Dun, rises near Saltersbrook, upon the high ground sailed SneaLsden or Snailaden Pike, near the border of Cheshire, and tursues an easterly course to Penistone, then turns south-east towards iheffield, receiving on its way the Little Don, the Ewden Brook, and he Loxley River. At Sheffield the Don is joined by the Shef or iheaf, which rises in the Derbyshire Mountains, and runs north-north sat, skirting the boundary of the county for a short distance, and eceiviug another small stream from the highlauds to the west. From ;heffield the Don runs north-east by Rotherham and Doncaster to Chorus, when it turns north, and runs to the Aire just below Snaith. Cho principal tributaries received along this part of its course are the ?other, which rises in Derbyshire (Dsanssettee], enters Yorkshire a ew miles south of Rotherham, and joins the Don at that town; the /earn, or Darn, the longest branch of which rites at the hill called )enby Moor, to the north of Penistone ; a stream of considerable ength which descends from Hemeworth, Kirkby, and Claytou in the :lay, and flows westward to the Den at Barsley; and the Went, which riginates in the last slope of the high lands on the west of the Ouse 'alley, and flows by Wentbridge and Kirk-Smeaton to the Don about aidway between Thorne and its junction with the Aire. The navi alien of the Don or Dun commences at Tiueley, south-west of Rather am, at which point the river is joined by the Sheffield Canal, a sepa ate undertaking, though formiug part of the same extended line of ommunication ; bnt in many parts below that point a navigation is ffected by artificial cuts to avoid bends and difficulties in the bed of he river. The first Act for this navigation was passed in 1726, aud here have since been several others, of which that of 1826 empowered he company of proprietors to make very extensive improvements by ew cuts and other works. The portion of navigation from Tinsley Doncaster, which by the old course was 21 miles long, is thus educed to 13 miles, with a fall of 674 feet by 11 locks. Similar im rovetnents have been effected in other parts of the navigatiou, and he total length of the improved Don navigation is about 39 miles, ith a total rise from the low-water mark in the Dutch River of 21 feet, effected by 16 lecke. This navigation is of very great im ortance for exporting the produce of the extensive coal- and iron orbs which abound at its western extremity, as well as the vast uantity of manufactured iron goods and cutlery produced in hefficld and its neighbourhood. The trade of Rotherham, the lime one and plaster at Sprotoborough and other places on the liue, and le agricultural produce of the neighbourhood of Doncaster, also institute considerable branches of traffic ; while the imports embrace nary article required for the supply of an extensive and populous lanufacturing district.