Details of one of the larger spurious shifts of the middle band, as observed before the brick pier supports of the optical frame had been properly overhauled.
The dots represent individual settings and readings of the micrometer cross wire set on the middle band during a pair of spins in opposite directions, while the speed was first increasing and then decreasing.
Corresponding concertina action (on same scale), or change in the breadth of the bands during the above spurious shift. Dots represent differences between the readings of a micrometer wire set on the yellow of the 1st order and the readings of the cross wire set on the middle band. The zero of the vertical scale is far below, 7 squares below 0. At that distance this figure may be placed above fig. 5.
