Carbon copy.
Handwritten postscript.
Holograph, signed.
Handwritten. May possibly be unfinished.
Bell Telephone Laboratories letterhead. Letter from W. L. Richards detailing his suggested corrections to a book (or manuscript?) Berliner had written and sent to him for his approval.
Carbon copy. Doodles on recto.
Allen's sketch of microphonic air-gap at the bottom of page 3. Continues with a handwritten postscript on p. 4. Contains Allen's thoughts on the proposed article for which he and Berliner have been trying to ca More
Date taken from context and sequence of letters.
Appears to relate directly to rest of 1926 correspondence between Berliner and Allen. Holograph, signed--may be copy. Contains suggestion to help Allen capture image of microphonic air-gap.
Picryl description: Public domain image of a picnic in the park, outdoor activity, leisure time, free to use, no copyright restrictions.