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as given above. For a long time the greatest
observed proper motion was that of a small
star 1830 Groombridge, nearly 7” a year;
but others have since been found reaching
as much as 10”.
Now the spectroscope enables the mo-
tion of stars to be detected at a single ob-
servation, but only that part of the motion
that is in the line of sight. For a complete
585
