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wards a red dust which fell knee-deep. The dust continued to fall for several 
days, and some distance out at sea. At night the mountain Jabel Dubbeh, 
a day’s journey inland, was seen giving out smoke and fire. 
In the succeeding August a steamer crossing the Caspian found in its 
middle a newly-elevated island some 200 feet long and six feet high. The 
ground, which smelt strongly of petroleum, was still quite soft and difficult to 
walk on, from the feet sinking in. 
In the December following came the eruption of Vesuvius, pouring out 
one more of the many lava coats which have made up its mass. Preceded 
by more than twenty distinct earthquake shocks, at mid-day on the 8th, 
the sky became completely dark over the Torre del Greco, and clouds 
of ashes were projected out from several jets on the sides of Vesuvius ; in the 
night ashes were succeeded by lava, which in the next morning had so 
hardened as to bear walking on, though the interior was so hot that a stick 
put into the cracks took fire. On M. P. de Tchihatcheff approaching the 
smoking hills, he saw the glowing scoriae, black ashes, and white steam, thrown 
out with intermittent shocks resembling the puffs of a steam-engine. The 
explosions of the new craters, as well as the flow of lava, almost ceased about 
the third day ; but in the mean time the central cone of Vesuvius, previously 
tranquil, began ejecting ashes and steam in dense clouds, which on the 23rd 
fell abundantly in the streets of Naples, — an event which has not occurred 
since 1822. There were in all about twelve new craters formed. 
At the same time the shore beneath Torre del Greco was permanently 
elevated about four feet, — a long line of shells and zoophytes being now raised 
that height above the sea-level. 
FFORTS have been made at various times since the introduction of 
railways to reduce the friction of the wheels of the carriages, and so 
to diminish the tractive resistance which the engine has to overcome. The 
failure of tyres, leading to frequent and fatal accidents, has of late drawn 
increasing attention to the subject, and various attempts have been made to 
remedy the defects of our present system of construction. Friction-wheels 
for bearings have been tried on the Eastern Counties Railway. Steel wheels 
and wheels with steel tyres have been adopted to some extent, and Mr. Bridges 
Adams has invented an elastic wheel, having a spring between the run 
and tyre, which exhibits great durability. Meanwhile M. Gerard proposes 
to abandon wheels altogether, and his plans have been experimented upon at 
the expense of the French emperor. Fie places the carriages upon sledges, 
which are hollow, to receive water forced in under pressure : this water passes 
in a minute film between the sledge and rail, so that the carriage rather floats 
than slides, and the tractive resistance is said to be very small. Further 
experiments under the direction of a commission are contemplated. 
Machinery worked by compressed air, like that on one side of the Mont 
Cenis tunnel, alluded to in our last number, has been employed in hewing 
coal in a pit near Ardsley, under a patent of Messrs. Donisthorpe, Firth, and 
Rothery. The air is compressed by a powerful steam-engine at the pit’s 
mouth to 50 lb. per square inch, and thus conducted in bitumenized pipes a 
MECHANICAL SCIENCE. 
