View looking through the Great Drain ... Nomlas photo (31-E-74). Horizontal (normal) ... 5 August 1931
Cover slabs over the Great Drain ... Nomlas (31-E-42) Horizontal (normal) ... 20 July 1931
Investigating the Great Drain ... 31-E-48 (Nomlas.) Horizontal (normal) ... 22 July 1931
Working plans of section Ζ in 1954. Earlier periods ... John Travlos Dorothy Burr Thompson ... Original missing. Old grid. Not an accurate plan! Faint Diazotype Drafting Ink Pencil Pen ... 1954
Working plans of section Ζ in 1954. Earlier periods ... John Travlos Dorothy Burr Thompson ... 1954
Plan and section of east branch of Great Drain; unfinished ... John Travlos ... Possibly section Λ? Dirty Cartridge Paper Drafting Ink
Plan of the Great Drain at fork in Section Ζ ... Charles S. Spector ... Dirty Cartridge Paper Drafting Ink ... 1933
Plan and elevation of the Great Drain in Section E ... Charles S. Spector ... Dirty Cartridge Paper Drafting Ink ... 1933
