The second object that comes under consideration is the inclosing the piece of ground at Arbroath for a work-yard. This may either be done by a ruble wall or a wooden fence, but the former is preferable, because several buildings must be made for stores, and for floors, to mark out the different courses with the dove-tails as they form the building, so that the ruble wall may form part of these buildings. Sheds must also be erected for the masons to work in.
Thirdly, Two vessels, of about 30 tons each, for conveying stones from Arbroath to the Rock, should, without delay, be contracted for. These vessels must be built strong, and of good materials, and calculated to work well at sea, that no opportunity of going to the Rock may be lost.
Fourthly, A crane for unloading the vessels should be established at Arbroath, and another at the Rock, for landing the materials, as also the necessary tools and triangles, with tackle for setting the stones in the work-yard, and at the Rock likewise, stone-carriages, jacks, &c.
Fifthly, Mooring-chains, anchors, buoys, with ropes, &c., to assist in landing the materials, and for enabling the men to leave the Rock when the tide prevents them from working.
Sixthly, A coffer-dam will be wanted, to the height of 4 or 5 feet, so as to enable the workmen to continue so much longer on the Rock than they could do, were the tide allowed to flow over the foundation when it rises above the level of the Rock.
Seventhly, Although we do not pretend to say that a stage, for the accommodation of the workmen, can with certainty be constructed on the Rock, yet it might be worth while to attempt the establishment of such a work, as, if it did answer, great facility in carrying forward the work would be obtained; and, should the project fail, the timber and iron can be applied to other uses, and the expence of the experiment cannot be great.
Eighthly, A variety of small tools, for cutting the foundation of the Rock, for dove-tailing the stones, and sundry other uses too tedious to mention, will also be wanted.
Ninthly, A quantity of Aberthaw lime should be procured, as well as other lime of the best quality which the country affords, and a small lime-kiln for burning it erected, and no more burned at once than can be used in a short time, that it may be always had as fresh as possible, as the less it is exposed to the air after being burned the better will it cement. Pozzolano or tarras should be got, if possible, to mix with the lime, these making the best cement that has yet been discovered; but, if it cannot be had, manganese, or even burnt ironstone, will form a good substitute. A quantity of Parker and Company’s Roman cement will be wanted, to keep the sea from washing out the other cement before it has time to harden in the joints.
Tenthly, Oak trenails will be required for fixing down the stones, while the building is in operation, and the several courses liable to be washed by the waves. Lead for running bolts into the Rock, &c. will also be necessary.