H, K. CARLETON. CV. 



on rolled iron girders. The walls are of cast iron to a height of 

 7 ', lined on the inside with sheet iron, the space between inner 

 and outer surfaces being utilised for the admission of fresh air to 

 the lantern, gratings being placed at intervals on the outside, 

 and brass hit and miss grating on the inside for regulating the 

 quantity and direction as required. Above the cast iron base is 

 an open framework 10' 3" high, having astragal bars paved with 

 polished plate glass §" thick in lozenge-shaped squares, so that 

 no vertical bars can obstruct the beam of light. A cast iron 

 gallery supported on cast iron ornamental brackets is carried 

 round the lantern both inside and out at the base of the glazed 

 framing to facilitate cleaning operations, the gallery has 

 perforated cast iron floors and light wrought iron handrail for 

 protection, and is accessible by means of short flights of step 

 ladder of wrought iron. The lantern room is roofed by a dome 

 having sixteen cast iron ribs covered inside and out with strong 

 copper sheeting, and surmounted by a strong copper ventilator, 

 6' diameter, with a weather vane in the centre which, acting 

 upon a dial visible in the room beneath, indicates to the keeper 

 on duty the direction of the wind, and so enables him to regulate 

 the admission of fresh air. 



The apparatus itself is of prismatic glass in gun-metal framing, 

 nine sided with concave sides. It is about 6' diameter and 

 9' high, partially domed or contracted at top to a diameter 

 of 2' 3* It is a first order dioptric revolving white light, triple 

 flashing every 20 seconds, and making one complete revolution 

 each minute and a half. The apparatus is attached to a cast iron 

 base or carriage fitted with a gun-metal toothed driving wheel, 

 and revolving on conical steel rollers, the driving wheel being 

 operated on by a gun-metal driving pinion worked by a clock- 

 work arrangement of steel and gun-metal, the motive power for 

 which is obtained by weights suspended on chains working in a 

 wrought iron tube 16" diameter passing through the whole 

 height of the tower, and having doors for access on each floor. 

 Should any accident occur to this machinery provision is made 

 for continuing the revolution of the lantern by hand gear. 



