Page:The story of the comets.djvu/194

148 "The head of the comet presented the great peculiarity of having two eccentric envelopes in addition to the ordinary bright envelope immediately surrounding the nucleus. The first envelope was a bright and sharply defined semi-circle surrounding the nucleus: the two eccentric envelopes were nearly as bright, and also very sharply defined, also semi-circular, having their centres placed (about) on the edge of the first envelope, and

COGGIA'S COMET OF 1874.

intersecting each other. The second centrical envelope just embraced both these eccentric envelopes, and was about half the width of the nebulous head of the comet. Between this second envelope and the ill-defined outline of the head (that is, between c and g) there were faintly marked outlines of other concentric envelopes. The nucleus, which, according to Hind, was 4000 miles in diameter, appeared to be somewhat flattened on