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pense. From correct measurements, I estimate the expense as follows:

1.-Cutting away to low water two pro-, L. S. d. jecting points of Rock, which are situated

on the Carnarvonshire shore

2.-Cutting away to low water the reef

of rocks called the Cribinnian

3.-Cutting off part of the Britannia Rock

4.-Cutting off to low water the Donkin Rock, the skirts of the Benlas Rock, and lowering the Platters

5.-Perches, &c. &c.

4,814 1 6

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£8,983 15 6

London,

16th February 1819. (Signed)

THOM. TELFORD.

Description of a Mooring Block.

By Mr. J. PARK, of Portsmouth.

With an Engraving.

The Gold Medal was presented to Mr. PARK for this Communication.

From the TRANSACTIONS of the SOCIETY, for the Encouragement of ARTS, MANUFACTURES, and COMMERCE.

IN October, 1795, I was appointed junior master-at

tendant of Portsmouth yard, and as the security of his Majesty's ships, and all works on float, relative thereto, are in the master-attendant's department exclusively, I applied myself as much as possible to gain a thorough knowledge of the harbour, as well as of the nature of the security and disposition of the moorings; and the more F became acquainted therewith, the less satisfied I was with

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the method by which the ground chain was secured, as a national evil attended it, and various other inconveni ences to the public service.

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The evil alluded to, was that of throwing some thousand tons of shingle-ballast annually on what is called the claws of the moorings to render them secure, which ballast was, by the wash of the tide, carried into the bed of the harbour and lakes where the ships ride...

Having arrived at the head of my department in April, 1812, I ventured humbly to recommend to the honourable Navy Board, considerable alterations in the arrangeinent of the moorings, which would not only tend to improve the harbour, by giving more space in the lower part, where the same was required for ships to pass and repass, but also afford accommodation to a greater number of them than hitherto could be laid up; the recommendation being favourably received, I was directed to proceed accordingly.

These alterations were effected, but the great and growing evil of filling up with ballast a harbour already too shallow, still continued, and produced an anxious wish for some substitute for the claw, by which the application of shingle ballast might be discontinued. I was accordingly induced to make several experiments, and after various trials, I submitted to the Navy Board a model of a cast-iron mooring-block which appeared to promise fair to do away every objection arising from the method of securing the ground chain, being at once a substitute both for claws and mooring anchors.

The Board directed two to be cast of such form and weight as I wished, and when received in the yard, trials to be made to ascertain what degree of resistance they possessed..

When received, trials were made under the inspection

of

of several experienced and distinguished naval officers, and the principal officers of the dock yard; which proving satisfactory, induced me to address the Navy Board on the 2nd November, 1814, detailing my sentiments, &c. relative to Portsmouth harbour, and the moorings, áccompanied by accurate statements of the trials made with the blocks, copies of which I have annexed hereto, having first obtained the Board's permission to do so.

A trial being ordered on a lighter block, and proving equally satisfactory, directions were shortly after given for their general adoption, to the exclusion of every thing hitherto used for securing moorings, and a contract immediately entered into for the supply of them,

The superiority of the block in question over both claws and anchors, is manifest, it will last for ages without repair, will resist much greater power than either, and completely obviate the use of shingle ballast, to render the mooring secure (which must hitherto have been extremely injurious to the harbour), as on applying a strain it has a tendency, arising from its form, to bury itself more and more under the surface until it becomes fixed; it is likewise free from liability to be hooked by ships' anchors, and the moorings thereby rendered insecure, which has been the case hitherto, as represented in my letter to the Board above quoted.

I now beg leave to notice the mooring-blocks in an economical point of view.

The largest blocks, adapted for first-rates' moorings, are now supplied for less than half the sum required to provide and fix what is termed a claw, and about a quarter of the cost of a mooring anchor.

It must also be considered that both the anchor and claw would require to be replaced in the course of 40 or 50 years (supposing them to remain undisturbed), besides

which the claw would require frequent repair from the effect of the worm during that period.

On the blocks already laid down at this port (although principally as substitutes for claws) there arises a saving to the public of upwards of £.3,000; and where it may be necessary to lay them down instead of anchors, the saving will be infinitely greater.

It may not be amiss to mention that an opinion prevailed that the block invented by me was only an improvement on one invented by Mr. Hemmans of Chatham Dock-yard some years ago, but on an examination of the two by a committee of the Navy Board, the same was clearly proved to be erroneous: the report to the Admiralty on that subject, and recommending the general adoption of my block, was as follows, viz.:

"The Committee has further to remark, that Mr. Park's block cannot be considered as an improvement on the plan of Mr. Hemmans, being totally dissimilar; but altogether as a new invention, and having the same object in view."

As a model and drawing of the block are forwarded, I decline giving any written description of it here, but should the Society require further particulars, I shall have 'much pleasure in furnishing them.

I have only now to observe, that having been influenced by a strong sense of public duty, and an ardent desire to be useful to my country, by overcoming the serious evils set forth in my narrative, I trust it will not be considered too presuming to request as a mark of your approbation that you will be pleased to give my invention publicity.

Copy

Copy of a Letter addressed to the Hon. the Navy Board.

Honourable Sirs,

Portsmouth-yard,
Nov. 2, 1814.

Having from my first appointment to Portsmouthyard as junior master attendant, dedicated as much time and attention as in my power towards acquiring a thorough knowledge of the harbour, both as to the depth of water and quality of the ground, and also to the method of preparing and laying down moorings, together with any improvements that might be made, either for their security, or for increasing their numbers by à more advantageous arrangement, or by laying down additional ones where found practicable.

I have in the course of my practice (which has been now upwards of 19 years), experienced many inconveniences, which I have long conceived might be removed by making some alteration in the manner of securing the ground chain.

I have likewise been of opinion, from an early period after my appointinent, that many advantageous alterations might be made among the moorings in various parts of the harbour, as well as that new moorings might be laid down both for ships of the line and frigates in the different Jakes, and having submitted the same to your Honourable Board by letters of the 30th April, 1812, and 26th July, 1814, was directed by your warrants of the 8th May, 1812, and 28th July, 1814, to carry the propositions into effect: in consequence of which several alterations have been made, and many new moorings laid down, and much may yet be done when the other duties of the port will admit; but as I am preparing a plan of the harbour, which will show the alterations, &c. much plainer than any

written

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