Chap. VIII.

BRITAIN.

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be opened at a time by hand, for this purpose; and to prevent any accident he suggestedthat a small tunnel with a valve should be used, in part to let in, and effectually to keepin the water. Without the use of men, it was imagined the harbour might by this meansbe kept clean; and occasionally they might be employed to remove what the sluices couldnot effectually do.

This harbour, which is on the left bank of the Tay, is often greatly inconvenienced bythe quantities of sand deposited within it. When the tide ebbs, it is brought down theriver, and when it flows it is brought from what has previously been carried out to sea.Mr. Telford, in 1815, repaired and extended the quay, and constructed a new dock, 250yards long, and 150 yards broad.

An act of parliament was obtained in the year 1815, for the improvement of thisharbour, and the management vested in commissioners. Mr. Telford was employed tocarry on the several works, and a floating dock, 750 feet in length, and 450 feet inbreadth, with an entrance lock, 210 feet long between the gates, and 55 feet in width, hasbeen constructed, as well as a graving-dock, the floor of which is in’ length 265 feet, andbreadth at bottom 40 feet, and at top 68 feet.

On the site of the entrance lock, at ordinary spring tides, is a depth of water of 19 feet,and at neaps, of 14 feet. And the total cost of these works was 119,835/.

The ferries at Dundee required proper landing-places. One was formed on the north,nearly 150 yards in length, which has a parapet and raised footpath, as well as an inclinedslip for carriages and cattle, 30 feet in width; it is supported on arches, so that the fluxand reflux of the tide is not prevented from scouring the back of the protecting pier of the ’western harbour.

On the south side are two connected slips with a protecting wall between them, so thatthere is shelter provided against all winds; and in every state of the tide, embarkation maygo on, and boats be under shelter.

The cost of these slips and approaches was 24,600/.

Bell Rock Lighthouse is situated in west longitude 2° 22', and north longitude 56° 29',eleven miles south-west from the Redhead in Forfarshire. The rock on which it stands isa red sandstone, of a fine grain, and containing minute specks of mica; the surface is veryrugged, and full of cavities, owing to the fracture and overlapping of the strata. It con-sists of 'an upper and lower level, being highest at the north-east end, which is partiallyleft by the tide at low water of neaps, whilst the lower level is only seen at spring tides;at which time its dimensions are about 427 feet in length, and 230 feet in breadth.

The ordinary rise of spring tides is about 15 feet, and of neap tides 9 feet; but the stateof the weather varies this materially. The course of the flood tide in moderate weather issouth-west, and of the ebb tide north-east; and the spring tides have a velocity of about3 miles an hour near the rock; and neap tides about 1] miles.

This celebrated rock is 11 miles from the nearest land, and is the obstacle to thenavigation of the firths of Forth and Tay; it is also dangerous to all vessels traffickingthe North Sea and German Ocean. In the year 1806 an act of parliament was passed toconstruct upon it a lighthouse, and Mr. Robert Stevenson was appointed engineer to carrythe same into effect. The design approved of by the commissioners was one on the sameprinciple as the celebrated Eddystone.

A work-yard was established at Arbroath , and a quantity of granite was procured fromAberdeen for the outside casing, and sandstone from Dundee ; these materials beingprepared, and implements for lifting heavy blocks being provided, the works were begunon the rock on the 17th of August, 1807. The workmen commenced by boring a numberof holes, to receive the lower ends of six large beams and six smaller ones, which were tosupport a wooden beacon, or temporary residence for the workmen during the summermonths. Pieces of Memel timber 50 feet in length were placed round a circle 36 feet indiameter, and met together at the top, on which was constructed a wooden house, whichconsisted of three floors. The lower one was store-house and kitchen; the second, inwhich the beams crossed, was made into two cabins: one was occupied by the engineer,the other by his foreman; the upper room was fitted up with three rows of beds for thirtyworkmen.

Below these three apartments, at a height of 25 feet from the rock, was a temporaryfloor, on which the mortar was prepared, and a smith’s forge for sharpening the picks andworkmen’s tools was fixed. The violence of the sea at times, however, was sufficient tolift this floor, and send all that rested upon it adrift: yet during the five years thatoperations were carried on, this beacon, which was immersed every tide from 8 to 12 feetin water, was found of the greatest utility.

During the first part of the work, it was necessary at every tide to go to and fro invow boats, each of which contained sixteen persons. In the winter months, the workmenwere employed on shore preparing the various stones, which, after being carefully fittedtogether, were all numbered and marked as they were to be placed in the building; and

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