A constant difficulty in studying works on metrology is the need of distinguishing the absolute facts of the case from the web of theory into which each writer has woven them -- often the names used, and sometimes the very existence of the units in question, being entirely an assumption of the writer.
And coins have long been recognized as one of the great sources of metrology -- valuable for their wide and detailed range of information, though most unsatisfactory on account of the constant temptation to diminish their weight, a weakness which seldom allows us to reckon them as of the full standard.
Petrie, Inductive Metrology (1877) (principles and tentative results);
In spite of his scientific training in philology Lepsius left behind few translations of inscriptions or discussions of the meanings of words: by preference he attacked historical and archaeological problems connected with the ancient texts, the alphabet, the metrology, the names of metals and minerals, the chronology, the royal names.
4000; 400,000 Another unit, which has scarcely been recognized in metrology hitherto, is prominent in the weights from Egypt -- some 50 weights from Naucratis and 15 from 400 Defenneh plainly agreeing on this and on no other basis.
Buildings will generally yield up their builder's foot or cubit when examined (Inductive Metrology, p. 9).
Of water; also the cubic inch is very nearly 250 grains, while the gallon has actually been fixed at 10 lb of water; the first two are certainly mere coincidences, as may very probably be the last also, and yet they offer quite as tempting a base for theorizing as any connexions in ancient metrology.
Though no line can be drawn between ancient and modern metrology, yet, owing to neglect, and partly to the scarcity of materials, there is a gap of more than a thousand years over which the connexion of units of measure is mostly guess-work.