of the English and French observers. Professor Holden and Dr. Dickson
searched for intra-mercurial planets; Mr. Preston took the times of
contact; Dr. Hastings and Mr. Rockwell devoted their attention to
spectroscopic observations of the corona. Dr. Hastings' observations
have led to the production of a new theory of the corona. Briefly
stated, the theory is that the light seen around the sun during a total
eclipse is not due to a material substance enveloping the sun, but is a
phenomenon of diffraction.

From his observation during the eclipse of 1878, made at Central City,
Dr. Hastings conceived the first idea of this explanation of the solar
corona. Further study served to convince him of the truth of this
theory, but he had no means of proving it. Before the present eclipse,
however, he devised a crucial test of his theory. This test is based on
the following already known phenomena: When the moon covers the face of
the sun, an envelope of light is seen all round it; the envelope is
not visible when the sun is shining, on account of the sun's greater
brightness; this light is called the corona; it is extremely irregular
in outline. According to the drawing of Mr. J. E. Keeler at the eclipse
of 1878, it enveloped the sun as a hazy glow, extending for a distance
of several minutes of arc from the sun's limb and at two nearly opposite
points is extended out in two long streamers feathering off into space.
The opinion has been that this light was due to an atmosphere extending
millions of miles from the sun. According to Dr. Hastings' view, it must
be light from the sun which has undergone refraction, i.e., which has
been bent from its regular course by the interposition of an opaque body
like the moon.

In order to make this perfectly plain, suppose the front of a surface
of waves of any sort to be striking an object which resists them. If