the shadow, alluding
to the fact that they must be moving at the same rate as the shadow,
although their apparent motion was much slower, or like the shadows of
flying clouds. He attributes the discrepancy to optical illusion.

At Virginia City the _colors_ of the _ultra_ bands were observed, and
estimated at five seconds' duration from the edge of the shadow, which
is equal to about 4 miles in width. These are known to be the
strongest color bands in the diffraction spectrum, which accounts for
their being generally observed.

Mr. W.H. Bush, observing at Central City, in a communication to Prof.
Holden alludes to the brilliancy of the colors of these bands as seen
through small clouds floating near the sun's place during totality,
and of the rapid change of their rainbow colors as observed dashing
across the clouds with the rapidity of thought.

All of these bands, both ultra and infra, as seen in optical
experiments, are colored in reverse order, being from violet to red
for each band outward and inward from the edge of the shadow.

It is very probable that the velocity of the passage of all the bands
during a total eclipse very much modifies the distinctness of the
colors or possibly obliterates them by optically blending so as to
produce the dull white and black bands which occupied so large a
portion of this grand panorama.

The phenomenon of these faint colored bands, with the observed light
and dark shadows, may be attributed to one or all of the following
causes:

1. A change in the direction of a small portion of the sun's light
passing by the solid body of the moon, it being deflected outward by
repulsion or reflection from its surface, and other portions being
deflected inward after passing the body by mutual repulsion of its own
elements toward a _light vacuum_ or space devoid of the element of
vibration.

2. The colored spectral bands being the direct result of the property
of interference, or the want of correspondence of the wave lengths due
to divergence; the same phenomenon being also observed in convergent
light. This is practically illustrated in the hazy definition of the
reduced aperture of telescopes, and its peculiarities shown in the
spectral rings within and beyond the focus.

3. Chromatic dispersion by our atmosphere, together with selective
absorption, also by our atmosphere and its vapors, have been suggested
as causes in this curious and complicated phenomena.

In none of the rep