Great Drain 21-31/Η-ΙΕ. General View during cleaning, looking northeast and showing strosis over slabs at 25/Ι ... AMS Horizontal (normal)
Great Drain close-up after cleaning ... AMS Horizontal (normal)
Great Drain at 25/Ι, showing strosis which had joined over cover slabs ... AMS 1155 Horizontal (normal) ... 8 Jul 1933
