Downstream

‘At the east end [of the
basement floor near the
Embankment] is a large iron
grating, guarding a
mysterious and winding
cavern. On the occasion of
our visit the gate was open,
and I walked through, and
was surprised to find myself
suddenly on the bank of the
Thames. I fancy this subway
was used to bring building
materials by water, but there
were interesting rumours that