495 
of Edinburgh, Session 1885-86. 
revolving lights, and to confine the experiments to its use for fixed 
lights, in which, owing to the light being distributed equally over 
the horizon by the cylindric refractor, some advantage is gained by 
the employment of the larger flame of the gas.” And the Keport 
concludes as follows : — “ We have to point out that the experi- 
ments made, have been highly valuable in showing the limit to 
which the size of a radiant may with advantage be increased when 
used in the focus of the apparatus now employed in light- 
houses. ” 
Mr Wigham, with great perseverance, nevertheless continued his 
labours in improving his large burners, and in producing new 
burners of still larger sizes. He also introduced several of these 
large-sized burners into the same lantern, in connection with 
Fresnel’s 1st order lenses, so that from the same lantern he exhibited, 
under the name of biform, triform, and quadriform, two, three, and 
four burners, with a like number of Fresnel lenses, arranged one 
above another. 
The employment of this multiple system of lights in the same 
lantern was, on the recommendation of Mr Wigham, adopted by 
the Irish Lighthouse Board, at Galley Head, in the county of Cork, 
in 1878. One important advantage of this multiple system was 
the power of lighting or extinguishing one 6r more of these burners, 
according to the greater or less amount of haze or fog in the 
atmosphere. 
The Trinity House erected three experimental towers placed along 
side each other at the South Foreland Lighthouse, near Dover, and 
the photometric experiments were carried out by Mr Harold Dixon, 
M.A., of Balliol College, Oxford, while the officials of the Northern 
Lighthouse and Irish Lighthouse Boards were kindly invited to 
attend the experiments from time to time, as well as Mr A. G. 
Vernon Harcourt for the Board of Trade. 
The conclusions which the Trinity House have arrived at are the 
following, and I may state, that in so far as my opportunities of 
observation have enabled me to form an opinion, I fully concur in 
their judgment 
1. “ That the electric light as exhibited at South Foreland has 
proved to be the most powerful light under all conditions of weather, 
and to have the greatest penetrative power in fog.” 
