1878.] The British Association. 517 
8J- inches high, was used, of course the illuminating power 
would be enormously increased. He trusted that before long 
lighthouse authorities would sanction the construction of 
such lenses, and so gain the full benefit of the large flames 
which gas only could produce. Being fully convinced of the 
importance of using large lights in illuminating fogs, he deter- 
mined to use lenses to the utmost limit which was now per- 
mitted, and he designed a means by which he was able to 
quadruple the power of the largest gas-light. This plan 
consisted in placing two and three and four burners verti- 
cally over one another, and making an arrangement by 
which the produces of the combustion of the lower burners 
were turned outwards, so as not to interfere with the upper 
burners, while the supply of fresh air was given through 
cylindrical openings, having no contact with the flues. The 
illuminating power was thus materially increased. The 
quadriform apparatus eredted at Galley Head contains 
32 lenses. As the lenses touch each other the rays of light 
blend at a short distance, and throw out one bright light. 
It is calculated that its illuminating power coupled with 
this large gas-burner was about equal to one million sperm 
candles. The light at Galley Head is not only quadriform, 
but is also a group-flashing light — that is, the flashes from the 
lenses, instead of being simple flashes, were each of them, 
by the continual extinction and re-ignition of the gas, broken 
up into four or five beams, which constituted a group of 
flashes, recurring at regular intervals. This is accomplished 
by the same clockwork machinery as that by which the 
lenses were caused to revolve. The interval between the 
groups and flashes is one minute, and the interval between 
the flashes two seconds, during which the gas is shut off, 
and thus there is a great economy of gas. 
The second portion of the paper described the combined 
gas and eleCtric light for lighthouses. For use during fogs 
Mr. Wigham added an intense light to his large gas-burner, 
which consists of what he terms a core for his burners. He 
preferred the eleCtric light because of its greater intensity 
and the facility with which it could be applied. 
The third portion of the paper dealt with a mode of 
lighting sea beacons from a position on shore. When it is 
desired to maintain lights on beacons to which access by 
boats is difficult or expensive, Mr. Wigham advises the ap° 
plication of gas properly dried by chloride of calcium as the 
means of illumination. The gas station on shore may com- 
mand any number of beacons, which may be simultaneously 
lighted. During the daytime the gas was supplied at a 
