From a known optical illusion derived from interference or fits of perception, as illustrated in quick moving shadows, this great speed was not realized to the eye, as the observed motion of these shadows was apparently far less rapid than their reality.

The ultra or diffraction bands outside of the shadow were distinctly seen and described by Mr. J.E.  Keeler at Central City, both before and after totality.  He estimates the shadow bands at 8 inches wide and 4 feet apart.

Professor E.S.  Holden, also at Central City, estimated the dark bands as about 3 feet apart, and variable.

From estimates which he obtained from other observers of his party, the distances between the bands varied from 6 to l1/2 feet, but so quickly did they pass that they baffled all attempts to count even the number that passed in one second.

He observed the time of continuance of their passage from west to east as forty-eight seconds, which indicates a width of 33 miles of diffraction bands stretching outward from the edge of the shadow to the number of many thousands.

Mr. G.W.  Hill, at Denver, a little to the north of the central track of the shadow, observed the infra or bands within 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.