_Stone Roofs._


The Romans employed _pumice_ in building their arched incombustible
roofs. This porous material possessed the additional advantage, when
combined with good cement, of rendering the arched surface one united
petrifaction, opposing (in consequence of its firm union) little lateral
pressure, comparatively, against the sustaining walls.

Bonomi, the architect, suggests that the principal cause of the
destructiveness of fires in large buildings, is the want of arched
surfaces of incombustible materials. This has been disastrously
exemplified in the destruction of the choir of York Minster, where the
roof of the aisles, which are solidly arched with stone, suffered no
injury; while the choir-roof, although much more raised above the action
of the fire, has been entirely destroyed by it.

* * * * *


_Fossil Saurians._


Several beautiful specimens of fossil saurians, or animals of the lizard
tribe, have, as our scientific readers are aware, been found at Lyme, in
Dorsetshire; but the world would to this day have remained ignorant of
the treasures England possessed, but for the patient labours of three
female pioneers in this service, viz. _Mary Anning_, a dealer; _Miss
Congrieve_, and _Miss Philpots_, residents, who for years had been
collecting and preserving these bodies from the wreck of the coast; the