The only way of examining these is by drawing curves (28, 29), representing the frequency of occurrence of all the variations of a unit; for instance, in the Egyptian unit -- the kat -- counting in a large number how many occur between 140 and 141 grains, 141 and 142, and so on; such numbers represented by curves show at once where any particular varieties of the unit lie (see Naukratis, i.
(28) Id., Naukratis, i.
Petrie, &c., Naukratis I., third Memoir of the Egypt Exploration Fund (1886); E.
Gardner, &c., Naukratis II., sixth Memoir of same (1889); D.
Naukratis in the Egyptian Delta was famous under the Ptolemies for its brilliant venal women.