320 Royal Institution :— 
Vegetation, he concluded that, while parts of the Secondary conti- 
nent yet remain in that hemisphere incorporated more or less into 
the Post-cretaceous continent, other parts of it, such as Australia 
and New Zealand, have remained isolated up to the present time to 
an extent sufficient to preclude the migration of Mammalia and 
wingless Birds. He inferred that the wingless Birds, excepting the 
swift Struthionidz, have been preserved solely by isolation from the 
Carnivora, which do not appear as an important family until the 
Pliocene age; and he instanced the Gastrornis of the Eocene (which 
had affinities with the Solitaire and Notornis) as evidence that the 
apterous birds had survived until that period. 
An inference was then drawn that the remains of the Secondary 
continent, accumulated to the southward, caused cold currents to 
flow to the southern shores of the Post-cretaceous continent, causing 
the extinction of the bottom-feeding and shore-following Tetra- 
branchiata, to which Mr. Wood attributes the destruction of the 
Cestracionts which fed on them, and that of the marine Saurians 
that fed on the Cestracionts. The preservation of the Dibranchiata, 
on the contrary, was attributed to their being ocean-rangers. ‘The 
extinction of the Megalosauria he attributed to the effect produced 
on vegetation by the alternation of dry seasons during the year, 
brought about by a great equatorial extent of land,—the extinction 
of the herbivorous Megalosauria, by this cause, involving that of the 
carnivorous. 
The author also alluded to the contiguity of volcanos to the seas 
or great waters, which he considered to admit of explanation by 
every volcanic elevation causing a corresponding and contiguous 
depression, which either brings the sea or collects the land-drainage 
into contiguity with the volcanic region; and in conclusion he 
alluded to the law of natural selection and correlation of growth 
lately advanced by Mr. Darwin, in the soundness of which he 
asserted his belief. 
ROYAL INSTITUTION OF GREAT BRITAIN. 
March 9, 1860.—“ On Lighthouse Ilumination—the Electric 
Light.” By Professor Faraday, D.C.L., F.R.S. 
The use of light to guide the mariner as he approaches land, or 
passes through intricate channels, has, with the advance of society 
and its ever increasing interests, caused such a necessity for means 
more and more perfect, as to tax to the utmost the powers both of 
the philosopher and the practical man, in the development of the 
principles concerned, and their efficient application. Formerly the 
means were simple enough; and if the light of a lantern or torch 
was not sufficient to point out a position, a fire had to be made in 
their place. As the system became developed, it soon appeared 
that power could be obtained, not merely by increasing the light, 
but by directing the issuing rays: and this was in many cases a 
more powerfuland useful meansthan enlarging the combustion; leading 
to the diminution of the volume of the former with, at the same time, 
an increase in its inteusity. Direction was obtained, either by the 
use of lenses dependent altogether upon refraction, or of reflectors 
dependent upon metallic reflexion, [And some ancient specimens 
