S20

HISTORY OF ENGINEERING.

Book I,

sands. This channel is } mile broad and $ mile from the shore, and is continually changingits direction; it is, therefore, necessary constantly to move the position of this timber light-house, in order that it may be placed in such a manner that it covers the great lighthouse,to vessels entering. The herring fishery forms the principal trade, and the ships employedarc about 40 tons burthen.

Yarmouth is admirably situated for the commerce of the north of Europe , and for theinland navigation of the county of Suffolk , from which it is separated by the Waveney.The town, which is in the county of Norfolk , is placed upon a bank of sand that becamefirm ground, and was first inhabited about the time of the Norman conquest , when a wallwas built around the town, and a broad moat formed outside.

The haven has been a constant source of expense ; the present is the seventh which has beenformed, and it is yet subject to all the inconveniences of the former. It was executed underthe direction of Joas Johnson, a Dutchman of some experience, who commenced his ope-rations by driving and hedging down on the north side large stakes and piles to render thefoundations firm; upon the south side the same system was adopted, that the refluent tidemight be forced to run out by a north-east channel. Piers and a jetty were erected toprevent an overflow, and to preserve a sufficient depth of water for vessels to float at alltimes.

The north pier, which was the principal, was made 40 feet wide at bottom, 20 feet at top,and 235 yards long. The whole was executed with timber of large scantling bracedtogether, and bound with iron. This pier was defended by a jetty, 265 yards long, 16 feetwide at the base, and 8 feet above. The south pier, 340 yards long, 30 feet broad, and 30high, 24 feet of which were under water, was built to prevent the waters of the old havenfrom running out southward.

The haven measures between the two piers 1111 yards, and is constantly receiving someimprovement. There are two lighthouses on the coast for the benefit of Yarmouth Roads,one at Caister and another at Garleston ; this coast is very dangerous, and it is recordedthat more than 200 sail of vessels and 1000 men perished in one night, in the year 1692.

Numerous sand-banks on this coast are continually shifting, but the sea has notencroached upon the shore since the sixteenth century. The great estuary, in the time of theSaxons , reached as far as Norwich, which was then situated on an arm of the sea. SinceYarmouth was first occupied, the sands have wonderfully increased, and a line of dunes isformed across the entrance of the entire estuary, which increasing both in breadth andheight effectually has shut out the tides, and narrowed the passage of the river, which hasvaried its course several times; the tides at the river’s mouth now only rise 3 or 4 feet, andat springs 8 or 9. Thousands of acres have been reclaimed in consequence, which areinterspersed with upwards of sixty fresh water lakes, varying in depth from 10 to 30 feet,and in extent from 1 acre to 1000. The Yare passes through some, and by depositing itsearthy matter tends to render them a productive soil, if the sea does not again break in uponthem, which sooner or later must be the case, as the shore about Yarmouth is constantlywearing away by the current which sets on it from the north-west, preventing any per-manent delta from forming on this coast.

The Waveney, which separates Suffolk fre^n Norfolk , is navigable for 25 miles toBungay ; and the Yare, which also empties itself here, for 22 miles is navigable toNorwich.

Wells, a small sea-port town on the coast of Norfolk , possesses a good harbour with adeep channel, but difficult of access, in consequence of the shifting sands. About the year1719 the river which constitutes the harbour was improved, and a considerable quantity ofland, redeemed from the marshy state, was rendered valuable for agricultural purposes byembanking it, and preventing the sea from any longer overflowing. Holkham marsh,including the creeks, consisting of 560 acres, was embanked at the expense of LordLeicester, and 108 acres, called Wells marsh, at the expense of Sir Charles Turner; soonafter, upwards of 1500 acres more were reclaimed; and in the year 1738, immediatelybelow the town a sluice was formed called Friestone, after the name of the builder; it wasconstructed with fascines, stakes, piles, &c.; these in a very few years went to decay, themouth widened, and it became necessary to reconstruct it, which was effectually donein the year 1765, when the harbour and channel down to the pool or mouth, which openedinto the German Ocean, were perfectly scoured.

This second sluice soon required repairs, in consequence of the timber of which it wascomposed being eaten by the worm.

In the year 1782, so much mischief had accrued, that it became necessary, to prevent theloss of the harbour, that something effectual should be undertaken, and Mr. John Smeaton was called in to report upon the best means of performing the necessary works. This en-gineer found that as long as the sluice had been maintained in proper order, it had answeredthe intention of clearing and keeping in good condition the whole of the harbour and channelwhich intervened between the mouth of the sluice and the upper or south end of the pool ;that since its decay the pool had so filled up, that at low water there was not more than 6 feet