Fig. 1, 2, 3, of Plate XXVII. are drawn by a scale of 4-10ths of an inch to a foot, from an anchor of 80 cwt. Fig. 4. is' a section of the bars, as laid together in the smallest hoop of the shank for an anchor of 80 cwt., and is drawn by a scale of one inch to a foot. Fig. 5. is drawn to a different scale, merely to slim the form of the stock.
The following tables contain the dimensions of an chors of various weights, as now made in his majesty's dock-yards, and the value and number of anchors for ships of each class in the British navy. The bower or sheet anchor is the largest of the anchors, and is used for retaining the ship in any particular situation, when it is apt to be driven about by the violence of the winds. The stream anchor is a small anchor fixed to a stream cable, in order to ride in rivers and gentle streams. The kedge anchor, which is the smallest of the three, is used to stop the ship when kedging a river.
A new kind of anchor has been recently proposed by Mr James Stuard. As the uppermost fluke of the common anchor is sometimes dangerous to ships which happen to ground by it, and often occasions the anchor to be tripped by the cable taking hold of it on the ship's swing, he employs only one fluke. The shank is made very short, and the bars which compose the shank and arms are all of one piece, without any joining. The palm is made of cast iron, or of a cast iron shell, filled with lead, and the stock is composed of a wrought iron bolt, covered with cast iron. See Repertory of Arts, vol. v. p. 380.
In fixing the stock to the anchor, it has been very lately proposed by captain Ball of the royal navy, to in crease the size of the nut, so that it may extend on each side of the shank to 21 times the diameter of the shank, for the purpose of receiving two bolts through each projection ; these bolts keep together the two beams which form the stock, and completely prevent the stock from slipping off the shank, an accident which very fre quently happens in hot climates. In Plate XXVII. Fig.
3, we have represented at in, in dotted lines, only one of the projections. See Transactions of the Society of Arts for 1808.
In drawing up the preceding article, we have been much indebted to several excellent communications from Mr Thomas James, who superintends the construction of anchors in his majesty's dock-yard at Woolwich. The ingenious remarks on the consequences of over heating the bars, and the table of the establishment, and price of anchors, furnished by this gentleman, are par ticularly valuable.
On the construction of anchors, See Athenxus, Diep nosoph. Apollonius Rhodius. Strabo. Pliny. Bouguer, Traite du Wavire, p. 95. Aubin's D ithOnnaire de Ma rine. Fourmont's Hydrographie. Duharnel L'Art de la Fabriyue des Ancres, Mem. Acad. Par. 1761. Hist. p. 152. Arts et Metiers, tom. 1, 6, 7, 8, 31, 37, 40. Per rault Machin. Approuve, torn. i. p. 45. J. Bernouilli Recited des Pieces gui ont Remporte le Prix, tom. iii. m. 4. Tresaguet Recited, &c. torn. iii. m. 5. Dan. Ber nouilli, Recited, &c. tom. iii. m. 5. Dan. Bernouilli, Re cueil, Sr.c. tom. iii. m. 6. Marquis de Poleni, Recueil, &c. tom. iii. m. 7. Smeaton's Reports. Chapman Gil bert's Journal dcr Physik, vol. vi. p. 81. Stuard Reper tory of Arts, vol. v. p. 380. Transactions of the Society of Arts, for 1808, or Phil. Magazine, vol. xxxiii. p. 348. Murray's Treatise on S/0-building, &c. American Phil. 'Trans.. vol. ii. p. 311. Shipbuilder's Assistant. Elements and Practice of Rigging and Seamanship, vol. i. p. 77. Young's Xit. Philosophy, vol. ii. p. 24 _ _1,— 142. (7r)