Encyclopaedia Britannica, 11th Edition, "Echinoderma" to "Edward, prince of Wales": Volume 8, Slice 10Various
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Encyclopaedia Britannica, 11th Edition, "Echinoderma" to "Edward, prince of Wales": Volume 8, Slice 10
Various
Encyclopedias and dictionaries
The eclipse of April 16, 1874, was observed in South Africa by E.J.
Stone, H.M. astronomer at the Cape, who traced the coronal line about
30' (430,000 m.) from the sun's limb. The visual corona was seen to
extend in places some 90' from the limb.
The eclipse of April 6, 1875, was observed in Siam by Sir J. Norman
Lockyer and Professor Arthur Schuster. Their photographs showed the
calcium and hydrogen lines in the prominence spectrum.
The eclipse of July 29, 1878, was observed by many astronomers in the
United States along a line extending from Wyoming to Texas. A number of
the stations were at high altitudes (up to 14,000 ft.), and the sky was
generally very clear. The visible corona extended on both sides of the
sun along the ecliptic for immense distances--at least twelve lunar
diameters, about eleven million miles. Photographs taken by the parties
of Professors A. Hall and W. Harkness gave the details of the inner
corona and of the polar rays, showing the filamentous character of the
corona, especially at its base in the polar regions. A photograph taken
by the party of Professor E.S. Holden showed the outer corona to a
distance of 50' from the moon's limb. The bright-line spectrum of the
corona was excessively faint and, as the solar activity (measured by
sun-spot frequency) was near a minimum, it was concluded that the
brilliancy of the coronium line varied in the sun-spot period, a
conclusion which subsequent eclipse observations seem to have verified.
It is not yet certain that the other coronal spectrum lines vary in the
same way.
The eclipse of May 17, 1882, was observed in Egypt. On the photographs
of the corona the image of a bright comet was found, the first instance
of the sort. (A faint comet was found on the plates of the Lick
Observatory eclipse expedition to Chile in 1893.) The slitless
spectroscope showed the green line (coronium) and D3 (helium) in the
coronal spectrum.
The eclipse of May 6, 1883, was observed from a small coral atoll in the
South Pacific Ocean by parties from America, England, France, Austria
and Italy. A thorough search was made by Holden (with a 6 in. telescope)
for an intra-Mercurial planet, without success, during an unusually long
totality (5 m. 23 s.). J. Palisa also searched for such a planet.
Janssen again reported the presence of dark lines in the coronal
spectrum. "White" prominences were seen by P. Tacchini.
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