BOOK II.

3i

are exposed before his eyes. There are just as great differences in hills asthere are in mountains, yet the miner does not dig except in those situatedin mountainous districts, and even very rarely in those. It is however verylittle to be wondered at that the hill in the Island of Lemnos was excavated,for the whole is of a reddish-yellow colour, which furnishes for the inhabit-ants that valuable clay so especially beneficial to mankind 10 . In likemanner, other hills are excavated if chalk or other varieties of earth areexposed, but these are not prospected for.

There are likewise many varieties of valleys and plains. One kind isenclosed on the sides with its outlet and entrance open ; another has eitherits entrance or its outlet open and the rest of it is closed in; both of these areproperly called valleys. There is a third variety which is surrounded on allsides by mountains, and these are called convalles. Some valleys again,have recesses, and others have none ; one is wide, another narrow ; oneis long, another short; yet another kind is not higher than the neighbouringplain, and others are lower than the surrounding flat country. But theminer does not dig in those surrounded on all sides by mountains, nor in thosethat are open, unless there be a low plain close at hand, or unless a veinof metal descending from the mountains should extend into the valley.Plains differ from one another, one being situated at low elevation,and others higher, one being level and another with a slight incline. Theminer should never excavate the low-lying plain, nor one which is perfectlylevel, unless it be in some mountain, and rarely should he mine in the otherkinds of plains.

With regard to the conditions of the locality the miner shouldnot contemplate mining without considering whether the place becovered with trees or is bare. If it be a wooded place, he who digs therehas this advantage, besides others, that there will be an abundant supply ofwood for his underground timbering, his machinery, buildings, smelting,and other necessities. If there is no forest he should not mine there unlessthere is a river near, by which he can carry down the timber. Yet whereverthere is a hope that pure gold or gems may be found, the ground canbe turned up, even though there is no forest, because the gems need onlyto be polished and the gold to be purified. Therefore the inhabitants ofhot regions obtain these substances from rough and sandy places, wheresometimes there are not even shrubs, much less woods.

The miner should next consider the locality, as to whether it has aperpetual supply of running water, or whether it is always devoid of waterexcept when a torrent supplied by rains flows down from the summits of themountains. The place that Nature has provided with a river or stream can

i°Thi s island in the northern ^Egean Sea has produced this “ earth ” from before■Theophrastus’ time (372-287 b.c.) down to the present day. According to Dana (System ofMineralogy 689), it is cimolite, a hydrous silicate of aluminium. The Ancients distinguishedtwo kinds,-—one sort used as a pigment, and the other for medicinal purposes. This latterwa ® w ith great ceremony at a certain time of the year, moulded into cubes, and stampedWl1 . 1 a fat,—the symbol of Diana. It thus became known as terra sigillata, and was anarticle of apothecary commerce down to the last century. It is described by Galen (xii., 12 ),Dioscondes (v., 63), and Pliny (xxxv., 14), as a remedy for ulcers and snake bites.