Philadelphia rod (original) (raw)

A Philadelphia rod is a level staff used in surveying. The rod is used in levelling procedures to determine elevations and is read using a level. A Philadelphia rod consists of two sliding sections graduated in hundredths of a foot. On the front of the rod the graduation increasing from zero at the bottom. On the back of the rod the graduation decrease from 13.09 ft at the bottom to 7 ft. The division of the device in two sliding sections are devised for ease of transport. Readings of 7 ft (2.1 m) or less, and up to 13 ft (4.0 m), can be measured. It has a rear section that slides on the front section. The rod must be fully extended, when higher measurements are needed to avoid reading errors. Distances of up to 250 ft (76 m) may be read.