The first discovery of the Principia is due to Miss Greenall, who about 1905 was building a house close to the school and took care that certain remains found by her builders should be duly noted: excavations in 1906-7, however, left the size and extent of these remains somewhat uncertain and resulted in what we now know to be an incorrect plan. The work done last spring makes it plain (fig. 3) that the Principia fronted in normal fashion the main street of the fort (gravel laid on cobbles) runn ...