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
View looking through the Great Drain ... Nomlas photo (31-E-74). Horizontal (normal) ... 5 August 1931
