[7] Its place is indicated in my School Atlas, as well as (of course) in
my Library Atlas, from the latter of which the small maps illustrating
the present article have been pricked off. The new star is marked T in
the Crown (Map VIII.), and must not be confounded with the star τ,
as in Roscoe's Treatise on Spectral Analysis, and in some astronomical
works. The star τ is a well known fifth magnitude star, which has
shone with no perceptible increase or diminution of splendour since
Bayer's time certainly, and probably for thousands of years before.
[8] This chapter was first published in February, 1877, when the star
was already invisible to the naked eye.
[9] It will be remembered by those familiar with the history of solar
observation, that when the spectrum of the solar prominence was first
observed, the orange-yellow bright line was supposed to be the
well-known double sodium line. It is so near to this pair of lines, that
while they are called D 1 and D 2, it has been called D 3; and in a
spectroscope of small dispersive power the three would be seen as one.
[Illustration]