Plate X — Various Implements and Apparatus Connected With the Works
Pl. X.
Fig. 1.—is an elevation of one of the three large copper Lanterns carried by the Pharos Floating-Light, which was moored off the Bell Rock while the Light-house was erecting. In order to relieve this vessel of the cumbrous yards with which Floating-lights were in use to be fitted, these lanterns were so constructed as to clasp round the masts, and traverse upon them. This was effected by constructing them with a tube of copper in the centre, capable of receiving the mast, and through which it passed. The lanterns were first completely formed, and fitted with brass flanges; they were then cut longitudinally asunder, which conveniently admitted of their being screwed together on the masts, after the vessel was fully equipped and moored in her station. Letters a a a a shew part of one of the masts, b one of the tackle-hooks for raising and lowering the lanterns at pleasure, c c c c c c c c c c the brass flanges, with their screw-bolts, by which the body or case of the lantern was ultimately put together; d d d shew the position of certain holes in the bottom for the admission of air, f f f f the holes at the top, connected with the ventilation, to which the collar-pieces e e and g g form guards against the immediate effects of the weather. The detached diagram, upon an enlarged scale, shows the air-hole, which is marked m. The letters h h h h shew the part of the lantern which was glazed with plate-glass; i is one of the glass shutters, by which the lamps were trimmed; the lower half being raised, slides into a groove made for its reception; k k shew the range of ten agitable burners or lamps, out of which the oil cannot be spilt by the rolling motion of the ship. Each lamp having a silvered-copper speculum or reflector l l placed behind the flame, was found greatly to increase the brilliancy of the light.
Fig. 2.—is a cross section of the bottom of the lantern, shewing the mast a cut across, b b is the sole or bottom of the lantern, c c the flanges at the junction of the body, in reference to the same letter in Fig. 1.; d d d d the small holes for the admission of air, e e e the brass zone or chandelier, with its ten arms and sockets marked f f, &c. in which the stalks of the burners are inserted. The chandelier is made to traverse horizontally into a corresponding groove fixed upon the interior cylinder or case, through which the mast passes, and upon which the whole moves up and down. When, therefore, the lamps require to be trimmed or taken out of the lantern, the chandelier is turned until they are respectively brought opposite to the shutter marked i.
Fig. 3. is an enlarged view of one of the agitable burners a, with its reflector b, which last measures four inches over the lips, and is raised to the parabolic curve of three inches focus; c the socket, d the section of the moveable chandelier in its groove, answerable to letters k and l, Fig. 1., and f and e Fig. 2. In reference to Fig. 3., e e is a section of part of the central cylinder of the lantern and mast of the ship.
Fig. 4. represents one of the Mushroom-Anchors, constructed wholly of cast-iron, used for mooring the Floating-Light and other craft off the Bell Rock, to which part of the mooring-chain is attached. This diagram seems so obvious as to require no particular description. Towards the head a a the shank is strengthened by means of four feathers or brackets raised upon it, somewhat resembling the connecting gills of the vegetable mushroom. These anchors weighed from 14 to 21 cwt.
Figs. 5. to 9.—Quarry Tools.—Fig. 5. is a common stone-pick, weighing from 8 to 10 lb., shown with and without the handle, which measured about 2 feet in length, but is here shortened. Fig. 6. is the Aberdeen or granite pick, weighing from 6 to 16 lb. Fig. 7. is a quarry hammer, weighing from 6 to 8 lb. used for jumping or boring batt-holes in the Rock, and the trenail-holes in the courses of the building. Fig. 8. represents the boring-irons for the trenail-holes, measuring 1¾ inches in breadth at the cutting end, and varying in length according to the depth of the respective holes. Fig. 9. is the scraper used for cleaning the holes; the perforated end being applied with a piece of rag for drying up the moisture.
Fig. 10. represents one of the oaken trenails used for keeping the stones in their places while the building was within the ordinary range of the sea. The positions of these trenails may be traced in the small circular holes of the courses, in Plate XIII. Their lower ends were cut with a saw-draught as at letter a, into which a small wedge marked b was inserted, and the trenail having been driven home, the small wedge had the effect of tightening or fixing it. The upper end c was then cut off flush with the upper bed of the stone, when it was split, and another small wedge, marked d, driven into the chisel-mark, which completed the operation of fixing the trenails into their places.
Fig. 11. represents a pair of the oaken wedges inserted into corresponding grooves cut into the perpendicular joints of the stones in each course of the solid or lower part of the Light-house, as may be traced in the small oblong holes, marked in the joints of the courses in Plate XIII. These wedges were chiefly intended for bringing the dove-tailed parts of the stones to a general bearing. The thick end of the wedge marked a being dropped into its groove, the smaller end of the corresponding wedge b was then inserted, and driven home till some degree of tension or firmness was obtained. This operation of trenailing and wedging was followed from Mr Smeaton’s practice at the Edystone Light-house.
Fig. 12. is a section of one of the cast-iron mortar-tubs, with its pestle, shod or loaded with a piece of malleable iron.
Figs. 13. to 15.—Cast-Iron Plate-railway.—Fig. 13. is a longitudinal view of one length of the cast-iron railways erected upon the Rock; a a a a represent the stools or upright supports, b b are the tracks of the roadway, c c one of the side stays or braces. Fig. 14. is a cross section on the line A B of Fig. 15, in which a a is the support with its cross-brace f, bolted at g g g g; b b are the railway tracks, c c c c the stays, with their connecting bolts on each side, d d the sleeper or horizontal brace connecting the top of the stools, and forming a chair or seat for the rails and grated roadway; e e e e represent the batts and spear-bolts, with which the whole was connected to the Rock, by the process of wedging with timber and iron. Fig. 15. is a plan of the finished railway; a a a a are the feet of the stools, b b the side rails or waggon-tracks, c c the stays or side braces, d d the sleepers, and h h the grated footpath. The weight of a yard in length of the railways complete, of the height of four feet, as represented in these diagrams, may be estimated about 5 cwt.
Fig. 16. represents a plan of one of the railway waggons; a is the iron handle made to hook upon either end of the waggon, so as to prevent the necessity of turning it; b b is the body of the waggon, consisting of two pieces of oak timber, bolted upon the upper part of the double frame intended for accommodating the wheels to the circular track of the railway round the building. The upper and under frames are connected with the bolt c c, so as to admit of the movement above alluded to. For the same reason, a joint was formed in the perch or middle of the frame at d. The trucks or wheels e e e e were of cast-iron, measuring 15 inches in diameter. These waggons were always left upon the Rock, being simply turned upside down, or off their wheels, in a particular part, and were seldom moved by the sea, as they weighed about 2 cwt. each.
Fig. 17. The ten diagrams, marked a, b, c, d, e, f, g, h, i, and k, are a set of moulds for one course of the solid part of the building, by which the stones were cut and prepared in the work-yard previous to their being shipped for the Rock. The application and connection of these diagrams will be better understood by examining the courses of the building in Plate XIII.
Fig. 18. a Trainer or Rule, framed of timber, applied by the builders, for ascertaining the exact position of the stones of the respective courses. a is the eye or socket on which it was fitted to a steady-pin placed exactly in the centre. This rule was used chiefly for ascertaining the radiating direction of the stones, from the centre towards the circumference, being laid agreeably to corresponding notches and lines marked upon their upper-beds, so as to preserve band throughout the work, and prevent difficulty with the closing or finishing stones.
Fig. 19. is a perpendicular section of the carpenter’s jack, used with much advantage for shifting and turning the stones in the work-yard. The case of this machine was made of elm, and strongly bound at the ends with iron. It measured 4 feet in height, its greatest breadth 12 inches, and its thickness 6 inches. a a is the stock or case, b b the rack, fashioned at the lower end somewhat like the claws of a carpenter’s hammer. The upper end is of a forked form, both ends being conveniently applicable to the varied positions of the stones; c and d are the wheel and pinion work; e the handle by which the machinery is worked, affording a purchase or mechanical advantage in the ratio of about 64 to 1.
Fig. 20. is a plan of the useful machine called The Woolwich Sling-Cart, applicable to transporting large blocks of stone suspended between the wheels by means of a Lewis-batt. When a stone was of considerable length, it became necessary to employ a chain to steady it at the farther end, the application of which will be seen in this and the following figure. a a a a represent the shafts and body of the cart, b b b b the wheels, c c the handles passing between the spokes of the wheels, by which the machinery is worked for lifting the stone. The dotted line d d d d represents a plan of a stone in its state of suspension, e e e the wheel and pinion work, f the barrel or cylinder on which the chain turns as the stone is raised; g g is the tail-beam with its chain h h, and steady-pin i.
Fig. 21. represents the sling-cart in its working state, with letters corresponding to Fig. 20. Here the Bell Rock carter, and his horse, are shown, already noticed in the description of Plate VI., page 498.