Key points are not available for this paper at this time.
A proper motion survey of the northern hemisphere, utilizing first epoch plates made some thirty years ago with the 13 – inch Pluto search telescope of the Lowell Observatory, was begun in 1957. The relative proper motions of stars fainter than the eighth magnitude and with motions greater than 0.″26 per year are measured directly on the calibrated grid of the projection blink comparator.
H. L. Giclas (Wed,) studied this question.