"My much esteemed master and friend, Mr. Weston, who came from London to be witness of our proceedings, arrived at Plymouth during this interval. I went of]' with him early on Wednesday morning, the 17th, attended by Mr. Jessop and his company, and landed upon the rock at ten : Richardson and company were then about to begin to set the fifth tier, or circle of stone, which was to contain the eight cubes before described. These cubes were so disposed upon the surface of Course VI. that the cavities cut on the under side of Course VII. to take the upper half of each cube, should constant' y fill in the broad part of the stones of the fifth circle ; which will appear plain by considering the dotted lines relative to Course VII. upon the surfice of Course VI. (see Plate III. Figure 6.) There could consequently be no application of wedges in the upper course, to the fastening of the circle of stones, (No. 5,) upon their respective cubes : when therefore the stone respectively came upon them, we put as much mortar upon the top of the cube as would in part make good the joint between it and its cavity, but not enough quite to fill it ; because, if too full, there was no ready way for the superfluous mortar to escape ; but a hole, of the size of those for the trenails, being previously bored each cube : when the stone was set, wedged and trenailed, then it was very practicable, by dressing a trenail so as to Become a ram-rod, to drive as ninth mortar down the hole as would completely fill every vacancy between the stone and its cube: insomuch that we soon perceived, that if this was attempted before the stone was completely trenailed down, it would very easily raise the stone from its bed, as might indeed be expected from the principle of' hydrostatics: hut, being done after such completion, it brought the whole to the most solid bearing that could be wished ; and, when the cement was hardened, answered the end quite as effectually as if they had been wedged.
" It may here be very properly said, that since those cubes could be of little use in keeping the work firmly together, bufore the mortar was hardened ; and after that had taken place. they could be of no use; because the number of one hundred and eight trenails, of which one of these courses consisted when complete, being supposed sufficient to keep it from lifting and moving out of ifs place ; as the mortar hardened, and every additional course was an addition of its own weight upon the former, it' those cubes could have been dispensed with in the first instance, they might have been so ever after. This reasoning I can very well admit to lie true ; vet, when we have to 'do with, and to endeavour to control, those powers of nature that are subject to no calcu lation, 1 trust it will he deemed prudent not to omit, in such a case, anything that can without difficulty be applied, and that would he likely to add to the security. It may farther be remarked, that as this was intended to be a mass of stone, held together by the natural and artificial union of its parts, it would have been out of character, that, when completed, it should be beholden to certain parts of wood for its consolidation.
" I have mentioned, that I originally conceived more than one way of preventing the courses from shifting place upon one another. My first conceptions were to form a rise (or a depression) of three inches, bounded by a circle somewhat about the diameter of that in which the joggles are placed ; which step, or depression, would have formed a socket, whereby the courses would have been mutually engrafted, not much different from what nature has pointed out in the basaltine columns of the Giant's Causeway ; but, considering how much unnecessary trouble and intricacy would be hereby introduced, by one part of the bed of the same stone being liable to be three inches higher than the other, I judged that the end would he very sufficiently answered by the much more plain, easy, and simple method of joggles; especially as, for this purpose, the firmest and toughest kind of stone might be chosen, and the number multiplied at pleasure. One plug in the middle, of a foot square, and eight joggles of it foot cube each, of the hardest marble. disposed in the manner described, scented to me, along with the additional strength and security arising front the trenails, as also from the infinite number of little indentures upon the surfitce of the courses. as well as the le•is holes, each being filled with an exuberance of mortar, which, when hard, would in effect become a steady pin ; from the cohesion I if the mortar as a promising to be no less than that of the stone, together with the incumbent weight of every part of the building above ; every joint, thus separately considered, seemed, in point of firmness, so satisfactory to my mind, that if the whole of this proved too little, it was out of my power to conceive what would be enough.
" In the morning and evening's tide of the 17th, we set the whole of the fifth tier, and consequently the whole of the eight cubes were then inlaid. The morning of the 18th we again landed, and in this morning and evening's tide, though rough, we had got set five pieces of Circle VI. and had landed the remaining three ; as also one of the largest pieces of moor-stone fla the east side (see Plate IV. re 1.) This evening's tide we worked with links, and it began to blow so fresh that we had much ado to keep them in, being obliged to make a fire of them upon the surface of the work. We were under the necessity, at last, to quit the rock with some precipitation, and were very glad to get into our yawls; things being left in the following posture : Two of the pieces, Tier 6, were simply dropped into their places, on the north west side, while the third piece, being about a toll, and the piece of moonstone near upon two tons, were chained toge ther, and to the work of Course VII. that was already set ; these two loose pieces being upon the top of that course, near the east side ; the triangles we lashed down upon the floor of the work, as we had practised several times before. The sea became so rough in the night, that the Weston, at the transport buoy, was obliged to slip and make fi)r a harbour. The bad weather continued to increase till the 28th, when there was a violent storm at south-west.