This is the original vintage pen and ink interior illustration created by Don Sibley for a story by Clifford Simak that appeared in Galaxy Science Fiction Magazine, March 1951 (see a photo of the published story for reference).  The art for this two-page spread was done on one sheet of paper - and appeared on pp 64-65.  The overal size of the paper is  13.5" x 17" -each of the 3 images  is about 7" x 6" and it's signed bottom left image/page, see photo.