A guardbook of letters from the former Greenwich assistant Abraham Sharp (who initiated the correspondence) to Flamsteed, with some of the originally enclosed astronomical and mathematical notes, 162 folios. The letters are chiefly on the rectos, with the direction and note of receipt, contents and numbering by Flamsteed on the versos. The surviving series is substantially complete. Subjects discussed include mathematical and astronomical books, astronomical calculations, the aurora borealis, other observations, instruments, and the printing of Flamsteed's works.