VIII. LIGHTHOUSES, &C. 449 



2191. Facet Reflector. Specimen of a reflector and lamp 

 used first at Liverpool about the year 1763, and afterwards at 

 Lowestoft and other lighthouses. Trinity House, London. 



It is made of wood with facets of silvered glass, is nearly paraboloidal in 

 form, and is the earliest kind of reflector known to have been used in aid of 

 an oil lamp in lighthouse service. 



2192. Lamp and Reflector, as used in English floating lights 

 about the year 1809. The curve of the reflector is spherical. 



Trinity House, London. 



2193. Parabolic Reflector of Plated Copper, used in some 

 of the Northern Lighthouses. When the apparatus is to be 

 cleaned, the lamp is lowered out of the reflector on a sliding car- 

 riage, as arranged by the late Mr. Robert Stevenson in 1814. 

 The object of the sliding carriage is to insure the return of the 

 burner to the proper focus. 



W. and T. Stevenson, Northern Lighthouse Office. 



2194. Parabolic Reflector, formed by small facets of mirror- 

 glass, imbedded in plaster of Paris, used in the earliest of the 

 northern lighthouses till superseded by more perfect apparatus 

 in the beginning of the present century. 



W. and T. Stevenson, Northern Lighthouse Office. 



2195. Model of a First-class fixed Dioptric Light; 



scale, one-fifth of full size. 



W. and T. Stevenson, Northern Lighthouse Office. 



This apparatus consists of a central lenticular band, and an upper -and 

 lower set of reflecting prisms. The cylindrical belt with diagonal joints and 

 the upper and lower reflecting prisms were substituted by Mr. Alan Steven- 

 son, in 1836, for the segmental belt, and upper and lower silvered mirrors of 

 FresneFs first-class apparatus. 



2196. Model of a First-class Fresnel Revolving Ap- 

 paratus, as made for Skerry vore Lighthouse in 1843 ; scale, 

 one-fifth of full size. 



W. and T. Stevenson, Northern Lighthouse Office. 



The light is received and collected into eight horizontal beams by the 

 principal lenses the light which would escape above is collected into eight 

 inclined beams by small lenses, and reflected to the horizon by inclined mirrors. 

 The lower part of the light is sent equally to all parts of the horizon by 

 prismatic rings of glass, which act as mirrors. The rings at Skerry vore are 

 the first that were made of the largest or first order size, and were undertaken 

 by M. Soleil, on the proposal of Mr. Alan Stevenson. 



2197. Model of a First-class Holophotal Revolving 

 Apparatus ; scale, one-fifth of full size. 



W. and T. Stevenson, Northern Lighthouse Office. 

 39508. F f 



