fin- the purposes of Illumination in Lighthouses. 71 



2. By the use of Gas, we may greatly improve the present sys- 

 tem of Illumination by means of Reflectors. In all our light- 

 houses, an Argand burner with one wick is used, because an en- 

 largement of its size would cause a great divergency of the re- 

 flected light, and consequently a greater diminution of its inten- 

 sity, than there would be an increase from the augmentation of 

 the flame. By the use of gas, however, we can introduce a 

 burner with two or even three concentric flames, which will not 

 occupy more space than a single Argand burner, and which 

 will, therefore, greatly improve the present system of illumina- 

 tion. 



3. The use of Gas is peculiarly adapted to the new system of Il- 

 lumination by means of Lenses. As the lenses employed in light- 

 houses will in general vary from two to three feet in diameter, 

 the distance of the lamp will also vary from two to three feet, 

 which allows us to use a flame from two to four inches in dia- 

 meter. In oil lamps with concentric wicks, it is necessary to 

 supply the flame with superabundant oil, by means of a piece of 

 clock-work ; and the lamp and machinery for this purpose cost 

 ^45. A gas burner, producing the same intensity of light, 

 may be executed for g 3 or 4, and has, besides, the great ad- 

 vantage of never going out of repair ; whereas the French lamp 

 would require to be under the superintendence of a person well 

 acquainted with mechanism. Independent, therefore, of the 

 great saving of expence, the substitution of a gas burner is pe- 

 culiarly applicable in lighthouses, where the machinery is not 

 only liable to go wrong, but where it cannot easily be repaired. 



1 have thus endeavoured to explain, as briefly as possible, 

 the new system of illumination for lighthouses. Discouraging 





