Plate X.
VARIOUS IMPLEMENTS AND APPARATUS CONNECTED WITH THE WORKS.
CERTAIN IMPLEMENTS connected with the BELL ROCK WORKS
Drawn by G. C. Scott
Engd. by E. Mitchell
PLATE X.
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.