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suggested by me, which is based on the use of a second practically vanishing trian-
gle (cf. figure)
(Since the anticipated effect is proportional to the area , for small ,
the small triangle virtually vanishes, and so f[orth]. This should serve as an aid to-
ward determining the origin, besides Michelson’s brilliant idea with the covering
and uncovering of one half of the plate P.) Now Michelson writes me enthusiasti-
cally that this arrangement has proven its worth; where were both small
enough, the two fringe systems overlapped by much less than fringe-width.
So Michelson decided to use this convenient arrangement in the coming summer
for measurements.[6] I shall not neglect to inform you of each step forward. You
have surely received the offprint of my paper on Propag[ati]on of Light in
Rot[ating] System[s] (Journ. Opt. Soc. of America)?[7] After completion of Mich-
elson’s experiments, I am thinking of elaborating on some details.
There only remains for me to wish you and your family all the best, in every
respect, for the approaching New Year 1922, among which will be another brilliant
confirmation of your theory in September (Christmas Islands).[8] I discover in Sci-
ence that you are probably participating personally in the Germano-Danish
expedition.[9]
With cordial regards from your very devoted servant,
Ludwig Silberstein.
P
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