Page:MillerKelvin.djvu/2

754 selected in which the motion of the earth was in the plane of the apparatus. In the first part of July, the direction of motion at these two times apparently differed by 115°; the morning and evening sets of observations were combined by taking into account this difference. In all, more than 250 turns were observed.

The velocity of the earth in July may be assumed to be 33·5 kilometres a second. The length of path in our apparatus was 32·2 metres, and the effect to be expected (on the original theory) is 1·4 wave-lengths.

We have established that, if there is any effect, it is not more than 0·015 wave-length.