George Sorocold, Derby Water Engineer
Record Souff and Elm Water Pipes in Derby page 103
1. St. Alkmunds Churchyard
2. Amen Alley
3. Bridgegate the upper end ... continued

This index records the position of underground water pipes made by boring our Elm trees.
Pipes (P) is assumed to be internal bore in inches.
Suffs (su) is Sough which is probably an open channel in the street for conveying waste water.
The measurements in feet and inches are the distances from various buildings to the pipe and the direction of measurement from the building.

from an article about George Sorocold a Pioneer of Water Supply in Derby - By F Williamson, F.R.Hist.S.