Year: 1873

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Professor Balfour Stewart, in re-
cent popular lecture, compares the sun
and the earth to great heat engines !;
and said that in the same way as the air
of an engine was caused to pass from
warm place to a cold one, currents of
air passed from the hottest parts of the
earth towards the poles, and Ujce Versa.
The sailor who raised his sail, and the
miller who ground his corn, took advan-
tage of the work done by the earth in
this way. There was no direct evidence
that currents of air passed from the
suns poles to its equator and back
again, but there was evidence of ascend
ing and descending currents in the at
mosphere of the sun. The currents
moved at the rate of thirty to forty
miles an hour. In the course of their
progress they carried with them metal
lie vapors in the shape of clouds, which
caused the mottled appearance on the
suns surface The clouds afterwards
descended again in the manner of the
rain-clouds of the earth. If they i'm
agined themselves on the solar surface
they might, as they travelled, come to the
brink of some enormous chasm, some
three or four thousand miles in depth,
and wide enough to contain thirty or
forty worlds like ours. The bottom of
the chasm would be found to be very
dark the sides not quite so dark, but
darker than the surface of the sun.
This chasm was in fact what was called
a sun spot. They knew it was a chasm,
because when the spot was at the edge
of the SUN, the side of the chasm near
est the earth was invisible whilst the
other side was in view, and the same
thing occurred at the opposite side of
the sun. There we're also bright spots
to be seen in the suns atmosphere,
which had been proved to be projec-
tions from the surface. These prOjee-
tiOns were seen during an eclipse in
the shape of columns of red light shoot
ing out from the edge of the sun.
These showed that terrible disturbances
must be taking place in the suns at
mosphere, for the columns he had men
toned in reality consisted of currents
of hydrogen, carrying with them sodium
and magnesium. No doubt the sun
spot was caused by some cloud matter
that was falling in the atmosphere of
the sun. 1t was not at present known
as a certainty that the spots on the sun
had any influence on the earth +; but it
was remarkable coincidence that dur
ing the past few years, which had been
good wine years in Germany, the spots
on the sun had been few in number,
which led to the suspicion that some
connection existed between the sun
spots and the vegetation of this earth.
He also stated that during those years
when there were most of these spots
there were most magnetic disturbances
in our atmosphere. There also appear
ed to be some connection between the
epidemics which took place on this
earth and the appearances on the suns
surface; for during the years 1916,
1860, 1870, and the present year, in
which the potato disease was very pre-
valent, the spots on the sun were at the
maximum. As near as could be ascer-
tanned, also, the sweating sickness,
which broke out at different periods
about the end of the fifteenth and the
sixteenth century was more virulent
near the times of the maximum than at
the times of the minimum sun spots.
He thought he had succeeded in con-
vincing his audience that the problem
of the connection between the earth
and the sun was most important one,
and very expensive one to work out.
It was a problem that should be taken
up by all the civilized countries of the
world