[Footnote 17: The assertion of Tacitus, that Germany was
destitute of the precious metals, must be taken, even in his
own time, with some limitation, (Germania, c. 5. Annal. xi.
20.) According to Spener, (Hist. Germaniae Pragmatica, tom.
i. p. 351,) Argentifodinae in Hercyniis montibus, imperante
Othone magno (A.D. 968) primum apertae, largam etiam opes
augendi dederunt copiam: but Rimius (p. 258, 259) defers
till the year 1016 the discovery of the silver mines of
Grubenhagen, or the Upper Hartz, which were productive in
the beginning of the xivth century, and which still yield a
considerable revenue to the house of Brunswick.]