22 
NATURAL HISTORY NOTES. 
The Extraordinary Sunsets and Sunrises. —These were observed 
at Naples and all over Italy during the week ending Dec. 8th, and 
Father Denza, a meteorologist connected with the Observatory of 
Montcalieri, attempts to show that they are merely intensifications of 
a phenomenon not rare in mountainous or more southern regions. He 
recalls the fact that on the evenings from the 24tli to the 26tli of 
September, 1831, throughout Southern Europe, from Madrid to 
Odessa, the sky at sunset appeared of a deep orange colour and then 
vivid red ; and then says that these phenomena can be explained by 
the (hygrometric and barometric) state of the atmosphere. But he 
was evidently unaware, at the time, of the great extent of the earth’s 
surface over which these appearances have been visible, which puts such 
explanations and the references which have also been made to the 
aurora borealis and the zodiacal light altogether out of the question. 
The same phenomena were observed in Switzerland shortly after their 
appearance in Italy. It would be interesting to know if any previous 
similar sunset displays could be connected with volcanic outbursts. 
Volcanic Dust, in relation to the Kecent Sunsets and Sunrises. 
—A few further hints and suggestions as to the dependence of the 
recent wonderful sunrise and sunset phenomena on the presence of 
volcanic dust in the higher regions of the atmosphere have appeared 
in the Times newspaper lately, from various sources, which it may be 
worth while to collect together. Mr. Preece points out (Dec. 13) that 
the electrical state of the particles of dust ejected by a volcano must 
have an important influence on their distribution in the atmosphere. 
They must necessarily have at the moment of eruption electricity of 
the same sign as that of the earth, and therefore must be repelled by 
it, m opposition to the force of gravity, when the explosive impulse is 
expended, and thus their suspension in the air be immensely facilitated. 
In the second place, being all electrified with the same sign, their 
mutual repulsion must determine the extension in all directions of the 
cloud formed by them. This is supplemented by Mr. Crookes 
(Dec. 18), who recalls the fact that he showed in 1879, by the length of 
time during which two gold leaves repelled each other, that air, at a 
rarefaction of one millionth of an atmosphere (corresponding to a 
height of about 62 miles above the earth’s surface), is an almost perfect 
non-conductor of electricity, so that there is every reason to believe 
that the dust once projected in an electrified state to 50 or 60 miles 
from the surface would retain its charge almost indefinitely. Colonel 
Stuart Wortley calls attention (Dec. 18) to the circumstance that 
there are well-defined belts of the globe where such magnificent aerial 
effects are very common, and suggests that this may be due to the 
almost constant ejections from the great South American volcanoes. 
He mentions also the exceptional sunsets seen at Naples in 1862, 
during the eruption of Vesuvius in that year.—T. H. Waller, B.A., B.Sc. 
