380 Proceedings of Societies . [May, 
from M. Allard, DireCtor-General of the French Lighthouses, 
relative to the eleCtric lighthouses at Cape La Heve and Cape 
Grisnez, where Alliance magneto-eleCtric machines and Serrin 
lamps had been adopted. It was intended to exhibit the eleCtric 
light in the present year in a new lighthouse on the Isle of 
Planier, opposite Marseilles, and it had been decided to substi- 
tute the eleCtric light for the oil light in the Palmyre Lighthouse 
at the mouth of the Gironde. Some information was also given 
relative to the eleCtric lighthouses at Odessa and Port Said, 
these making ten in which the eleCtric light had already been 
established. The comparative cost and efficiency were shown 
of lighthouse luminaries produced by all the agents at present 
employed, viz., oil, coal gas, and electricity. Coal gas, on 
Wigham’s system, was applied to the Howth Bailey Lighthouse, 
Dublin Bay, by the Commissioners of Irish Lights, in June, 
1865, and it had since been extended to seven lighthouses on the 
coast of Ireland. In 1872 the Trinity House adopted it at the 
Haisborough High Lighthouse. The additional cost of the 
works necessary for the introduction of gas at this station was 
£1,996, and the annual maintenance of the gas establishment, 
including interest on first cost, &c., amounted to £832 4s. 3d. 
This light had a mean intensity of 1,173 candles, and a maximum 
intensity for thick weather of about 2,923 candles. In 1877 the 
necessary additions were made for lighting the Low Lighthouse 
(distant 776 yards), by gas from the same works, at a cost of 
£1,296. The system of Mr. Wigham had been further developed 
by introducing the flames of two, three, and four large burners 
o/er each other in the axis of the dioptric apparatus. In January 
of last year the Commissioners of Irish Lights adopted one of 
the latter lights in a new lighthouse at Galley Head, near Kin- 
salt*. The maximum intensity of the four burners combined for 
thick weather was about 5,012 candles. The author next gave 
statements showing the comparative focussing compactness of 
the lighthouse luminaries which had been referred to for utilising 
in optical apparatus, viz., the lights produced by oil, coal gas, 
and electricity. The focussing superiority of the eleCtric 
luminary, compared with the best of these, was as 616 to 1. 
Statements were given of the comparative average cost and 
annual maintenance of a single lighthouse (shore station) in this 
country, with colza oil } mineral oil, coal gas, and electricity, as 
the illuminating agents, both with and without a first-class 
20 horse-power siren fog signal. For a maximum degree of 
light equal to the single or combined intensity of the luminaries 
of the Lizard, the cost of the more perfect eleCtric luminary per 
unit of light provided was about 13-22 and 6-22 respectively of 
that of coal gas, and about 13-65 and 6-65 respectively of that 
of mineral oil, at their maximum intensities. With higher 
intensities of the eleCtric luminary the cost per unit would be 
more in its favour, no further addition to the working staff being 
