366 
POPULAR SCIENCE REVIEW. 
that petroleum, so exactly like coal oil in its properties, has been formed 
from marine vegetation. The vegetable origin of both, he contended, was 
indubitable. — Vide Mining Journal, April. 
Models of Pre-historic Pile-dwellings. — It is stated in the Athenaeum that 
Professor Keller, the distinguished investigator of the ancient lake settle- 
ments, has been requested by the French Government to send a model of a 
pile-structure to the Paris Exhibition. Professor Keller, who only lately has 
received the cross of the Legion of Honour from the Emperor, in acknow- 
ledgment of his indefatigable researches, will do his utmost to furnish a 
faithful copy of the curious pile buildings, for which a Robenhauser structure 
will serve as a pattern. The building will be erected on a large water-basin 
outside the circle of the Exhibition, which is to supply the steam-engines and 
to be ready in case of fire. It is to be completely furnished, in the style and 
fashion of the lake settlers. 
The Geology of the Bas-Boulonnais.— M. E. R-igaux’s exhaustive memoir, 
published in the Bulletin of the Academic Society of Boulogne, gives nu- 
merous sections of the rocks in this district. The Palaeozoic formations are 
(1) the Devonian, which extends from Blacourt stream, near the road between 
Calais and Boulogne, and disappears near Fiennes (at Caffiers it is overlain 
by Gault) ; and (2) the Carboniferous, consisting of, first, a Dolomitic bed, 
then a mass of Limestone, then Coal, and above that another bed of Lime- 
stone, similar to the one below. This succession M. Rigaux believes to have 
been due to a disturbance which has caused an inversion of the strata, so as 
to make the same bed of limestone appear above, as well as below the 
coal. 
The Geological History of Malta is very interestingly sketched in an 
article by Captain F. W. Hutton in the Geological Magazine for April. The 
author, after giving a detailed account of the deposits in the island, proceeds 
to offer some theoretical remarks as to their period of formation. The 
Maltese beds, lie thinks, were deposited at a time when probably the Alps, 
Apennines, and the mountains of Turkey, Greece, and North Africa, formed 
groups of islands in a shallow Miocene sea, which extended over the valley 
of the Danube, the greater part of Switzerland, and the valley of the Rhine, 
as far as Mayence. Central France, he supposes, in conformity with current 
views, to have been at that time land, with a large series of fresh-water lakes 
and several active volcanoes. After a long blank Etna was raised, and 
during its upheaval most of the faults were formed which appear in Maltese 
rock. Malta now was part of a continent which included most of Europe, 
the Mediterranean area, and the North of Africa. Then followed the Glacial 
period, during which the basin of what is now the Mediterranean sank — that 
part which now constitutes Malta to rise once more, barren and denuded of 
all its surface soil. 
The Exhaustion of our Coal-beds. — This subject, which has attracted so 
much general attention since Mr. J. Stuart Mill’s remarks in his speech on 
the malt-duty, will be found fully treated in an able article in our present 
number. We may mention also that in a volume recently published, an 
attempt is made to prove that our coal-deposits as yet unworked extend over 
a greater area than those now known. The author, Mr. Holdsworth, brings 
forward a great deal of sound evidence to show that the coal-beds dip 
