On the relative motion of the earth and the luminiferous æther

by Albert A. Michelson; Edward Williams Morley

would be

With fifty such couples the displacement would be

''. But astronomical observations in circumstances far less favorable than those in which these may be taken have been made to hundredths of a second; so that this new method bids fair to be at least as sensitive as the former.

The arrangement of apparatus might be as in fig. 2 ([Figure 07]);

, in the focus of the lens

, is a slit.