be recorded in a sketch. By the aid of photography a number of records
can be taken during the progress of totality. From a study of these
the extent of the corona is demonstrated in one case to extend to at
least six diameters of the moon, though the eye has traced it
farther. This corona is still one of the wonders of astronomy, and
leads to many questions. What is its consistency, if it extends many
million miles from the sun's surface? How is it that it opposed no
resistance to the motion of comets which have almost grazed the sun's
surface? Is this the origin of the zodiacal light? The character of
the corona in photographic records has been shown to depend upon the
phase of the sun-spot period. During the sun-spot maximum the corona
seems most developed over the spot-zones--i.e., neither at the
equator nor the poles. The four great sheaves of light give it a
square appearance, and are made up of rays or plumes, delicate like
the petals of a flower. During a minimum the nebulous ring seems to
be made of tufts of fine hairs with aigrettes or radiations from both
poles, and streamers from the equator.

[Illustration: SOLAR ECLIPSE, 1882. From drawing by W. H. Wesley,
Secretary R.A.S.; showing the prominences, the corona, and an unknown
comet.]


On September 19th, 1868, eclipse spectroscopy began with the Indian
eclipse, in which all observers found that the red prominences showed
a bright line spectrum, indicating the presence of hydrogen and other
gases. So bright was it that Jansen exclaimed: "_Je verrai ces
lignes-la en dehors des eclipses_." And the next day he observed the
lines at the edge of the uneclipsed sun. Huggins had suggested this
observation in February, 1868, his idea being to use prisms of such