Edwin A. Link, Jr. presented this bubble sextant, in a beautiful alligator
case, to P. V. H. Weems. It is a standard A-12 with an attachment that enables
the user to view the real horizon. Link applied for a patent on this feature in
1943.
Ref: Link Bubble Sextant (Octant) Model A-12 Handbook: Description,
Operation, Use, Adjustment (Binghamton, N.Y.: Link Aviation Devices, Inc., 1943).
Edwin A. Link, Jr., "Navigation Instrument Including a Horizon
Attachment," U.S. patent #2,395,559
