near Coates, and level; thence to the Thames and Isis Navigation, twenty miles and three-eighths, with a fall of 134 feet by fourteen locks. The first four miles of this canal from Stroud is of the same width and depth as the Stroudwater Navigation, and calculated for the Severn Boats; the remainder of the line is 42 feet wide at top, 30 at bottom, and 5 feet deep, and the locks admit boats of 80 feet in length and 12 feet wide.
The famous tunnel at Sapperton, which was constructed by Mr. R. Whitworth, the engineer employed on this canal, is two miles and three-eighths in length; the arch is 15 feet wide in the clear, and 250 feet beneath the highest point of the hill, which is of hard rock, some of it so solid as to need no arch of masonry to support it; the other parts are arched above and have inverted arches in the bottom. It was first passed on the 20th April, 1789, and on the 19th November following the first vessel passed from the Severn into the Thames.
On the 19th July, 1778, during the execution of this work, his late Majesty King George the Third went to view the tunnel, with which he expressed himself much astonished, and on the construction of which he bestowed the highest praise.
The advantages of forming a communication between the Rivers Thames and Severn, have been always so apparent, that as long ago as the reign of Charles the Second, a bill was introduced into parliament for making the connection by means of the River Avon. It was not however acted upon. At the time the first act was obtained for effecting the junction of these rivers, by means of this canal, the project held out as fair prospects of success and pecuniary advantage to the promoters as any undertaking of the kind in the kingdom.
By connecting London with Bristol, Gloucester and Worcester, and other towns on the banks of the Severn, a safe and easy course to London is opened for not only the trade of Gloucestershire and Worcestershire, but also that of Herefordshire, Monmouthshire and South Wales; to which might be added the trade of the towns on the Thames, which receive their supplies of coal from the mines connected with the Severn. These prospects have not, however, been realized to the extent that was expected, owing, in a great measure, to the inefficient state of the navigation of the upper
