Base map is GSGS 2291(a), with manuscript additions showing sheet lines of GSGS series 1764 and 2571. Also shows areas covered by material held in Original Surveys, with references to page numbers in the Original Surveys ledger
Vertical aerial photographs showing the locations, corrections and additions to points identified on GSGS 3918 sheets 13, 15, 16 and 18. Housed in 6 card folders bearing the numbers 'Allegato N1' to 'Allegato N6'. Each folder also contains a folio referring users to memoranda that were not pres...