ALS, one page, 6.5 x 8.5, no date. Letter to Dale Parry, in part: "To search for planets, one needs a wide angle photographic telescope to cover as much area as possible. I made a pair f 14 x 17 inch plates on 23 Jan and 29 Jan 1930. I scanned these with alternating views, looking for a faint-star-like image that shifted positions 1/8 inch against the star background (1 hour exposure each). There were approximately 160,000 star images on the discovery pair of plates. Scanning with rapid alternating views under a Blink-microscopic comparator. Very tedious." In fine condition.
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