" The manlier in which it was executed was as follows : (see Plate IV Figure 6.) At each end of each stone, answerable to the middle. between the inside of the wall and the outside, was sunk a groove, two inches and a half wide and three deep, running from the top to the : when, therefore. two contiguous pieces of stone were put together in their places, the two grooves being applied to each other, they would form a rhomb of six inches in length and two inches and a half in breadth, which in this state would be an unoccupied cavity from the top to the bottom of each course ; the rest of the joint, whore the sin thees of the two stones applied to each other, was made good with mortar in the ordinary way, and brought together by the gentle blows of a beetle. For the groove m•ntioned, a solid rhomh was prepared. of ?lemt two inches thick by live inches broad, and in length a little less than the depth of the cavity, which generally was eighteen Or twenty inches ; and for the sake of the firmness of those slender pieces of stone, I made choice of the flat paving-stones front Purbeck, which is a laminated marble of great strength and solidity. The joint stones (which was the name we gave those rhombs) thus prepared, would readily go down the cavities ; but, to fix them solid, a quantity of well-tempered mortar was prepared, made more soft than ordinary. by the addition of a little water ; a competent quantity being put down to the bottom of the hole, the joint-stone was put down upon it, and, by the simple pressure of the hand, was forced down to the bottom, causing the semifluid mortar to rise up to the top, and completely fill the cavity ; and, when forced down in the way described, having in this state a small quantity of superlluous moisture about it, a few very gentle blows, or raps, were given upon the top of it by the handle of a mason's trowel, which producing a small degree of agitation, while the dry stones were absorbing the moisture, contributed (like the beating of mortar) to bring all the parts into their most friendly state of contact, and, in consequence, to their firmest state of union ; and this happened in the course of a few minutes, so that no litrther agitation could be of any service.
" As the cramps, that were to bind the contiguous pieces together, must cross the joints upon their upper surface, they were of course to be applied after the were settled in their places. Precaution was therefige neeessaty not to apply too much exertion in forcing down the joint stones : for, however gentle the operation may appear, according as it has been described, yet it was found advisable not to put in the joint stones till an additional piece had been got dow it upon its joggles, and plain-juinted at each side of the tw o pieces, whose johit-stone was to be put in ; for, by this means, they were the united effoits of all the joggles, and adhesion of the beds of two stones on each side of that where the etlint was applied. Without any atten tion to this, the lateral force arising front merely pressing down a joint-stone was capable of breaking the adhesion of the joint where it was applied.
"The cramping was applied the last thing. The top or
flat liars of the cramps were about thirteen inches long, two inches hroad, -and five-eighths of an inch thick, and were turned down at each end about three inches in length; forming a cylinder of one and one-eighth of an inch in diameter. Jumper-holes were previously bored when upon the platform, and the cramps fitted to their places ; the sur face of the stone under each cramp being sunk three-fourths of an inch, so that the two stones together would completely receive, or rather bury, the cramps: the joint-stones, as said above, being made so much shorter than the height of the course, as not to interrupt the bedding of the cramp. The places for the cramps being properly fitted and cleared, (as we now were not liable to be driven off the work in a moment, as had formerly been the case,) we took the olq.or tunity, whenever time allowed it, of fixing the cramps of a whole course together. There was no danger of the cramps not fitting; as, besides that all the cramps were forged to tit a having a couple of holes at the assigned distance, they were also fitted and marked to their particular places at Mill Bay, while upon the platflam. Every cramp being now ultimately tried to its place, it was then put into a kettle of lead, made red hot ; and the cramp continued there till it was also reddish. About a spoonful of oil was poured into the two eramp-holes. and the cramp being put into its place, the ebullition of the oil caused by the (teat of the iron quickly gave a complete oily surface, not only to the whole cramp, but to the whole unoccupied cavity in the stone ; then the hot lead being poured upon it, the unctuous matter caused the metal to run into and occupy the most minute cavity unfilled, and completely to cover each cramp ; and they became by this means defended from the salts of the sea, even had they remained uncovered, upon Mr. Rudyerd's principle. Mr. Rudyerd had used coarse pewter. The lead we used was slag lead, which is harder and stiffer than fine lead : and, as we used no cramps, as an essential part of the building, till above the store-room floor, I judged pewter, merely for the sake of there to be unnecessary. By cramping, in general, a whole course toge w the contraction of the iron in cooling would greatly add to the tightness wherewith every stone was bound to its fellow. Thus according to this mode of fixing, (besides the union of time parts by the mortar itself,) to resist all violence and derangement whilst it was doing, and before the indura tion of the mortar, every course was retained in its place by sixteen joggles, and each single stone by two halfljoggles at its lower bed ; they were farther steadied to each other by the joint-stones, and lastly by the cramps, which completely prevented a separation ; and this method proved so eflec tual, that we were not only free from all derangement of the stones when in their places, but I did not find ti leaky joint, except one, in the whole building. By a (Inc consider ation of Plate IV., with the particular references to it, the whole of this process will become perfectly intelligible.