"Then I felt like some watcher of the skies
When a new planet swims into his ken."
-Keats
//
Chapter 9
The Ninth Planet Discovered
On the morning of February 18, I placed the January 23 and January 29 Gem plates on the Blink-Comparator, starting on the east
half. This was a most fortunate decision. Had it been otherwise, Pluto might not have been discovered in 1930.
By four o'clock that afternoon, Mountain Standard Time, I
had covered one-fourth of the pair. After completing a horizontal strip on the left half, I would roll the horizontal carriage
back to the center north-south line (which I always drew as a
thin ink line on the back of the later plate of the pair.) I had
established this habit of progressing to the left, so I would not
forget which way I was going, in case of interruptions.
I could vary the speed of the shutter as it switched views
from one plate to the other, by means of a rheostat. I found from
experience that about three alternating views per second was the
I raised the eyepiece assembly to the next horizontal strip.
At the center line, I had the guide star Delta Gem in the small
rectangular field of the eyepiece. After scanning a few fields
to the left, I turned the next field into view. Suddenly I spied
Tombaugh, Clyde William, 1906-1997. Out of the darkness: The planet Pluto; Manuscripts
Digital Publisher
New Mexico State University Library
Collection
NMSU Department of Astronomy: Clyde W. Tombaugh Papers
Digital Identifier
Ms0407pp054001_0010001.tif
Source
Scan produced from physical item held by the NMSU Library Archives & Special Collections Department
Type
Text
Format
image/tiff
Language
eng
OCR
"Then I felt like some watcher of the skies
When a new planet swims into his ken."
-Keats
//
Chapter 9
The Ninth Planet Discovered
On the morning of February 18, I placed the January 23 and January 29 Gem plates on the Blink-Comparator, starting on the east
half. This was a most fortunate decision. Had it been otherwise, Pluto might not have been discovered in 1930.
By four o'clock that afternoon, Mountain Standard Time, I
had covered one-fourth of the pair. After completing a horizontal strip on the left half, I would roll the horizontal carriage
back to the center north-south line (which I always drew as a
thin ink line on the back of the later plate of the pair.) I had
established this habit of progressing to the left, so I would not
forget which way I was going, in case of interruptions.
I could vary the speed of the shutter as it switched views
from one plate to the other, by means of a rheostat. I found from
experience that about three alternating views per second was the
I raised the eyepiece assembly to the next horizontal strip.
At the center line, I had the guide star Delta Gem in the small
rectangular field of the eyepiece. After scanning a few fields
to the left, I turned the next field into view. Suddenly I spied
