i 



BOOK V. 119 



out because of the hardness or other difficulty, and the drift or tunnel is 

 low, a heap of dried logs is placed against the rock and fired ; if the drift or 

 tunnel is high, two heaps are necessary, of which one is placed above the 

 other, and both burn until the fire has consumed them. Tliis force does not 

 generally soften a large portion of the vein, but only some of the surface. 

 When the rock in the hanging or footwall can be worked by the iron tools 

 and the vein is so hard that it is not tractable to the same tools, then the 

 walls are hollowed out ; if this be in the end of the drift or tunnel or above 

 or below, the vein is then broken by fire, but not by the same method ; for 

 if the hollow is wide, as many logs are piled into it as possible, but if narrow, 

 only a few. By the one method the greater fire separates the vein more 

 completely from the footwall or sometimes from the hangingwall, and by the 

 other, the smaller fire breaks away less of the vein from the rock, because in 

 that case the fire is confined and kept in check by portions of the rock which 

 surround the wood held in such a narrow excavation. Further, if the 

 excavation is low, only one pile of logs is placed in it, if high, there are 

 two, one placed above the other, by which plan the lower bundle being 

 kindled sets alight the upper one ; and the fire being driven by the draught 

 into the vein, separates it from the rock which, however hard it may be, often 

 becomes so softened as to be the most easily breakable of all. Applying this 

 principle, Hannibal, the Carthaginian General, imitating the Spanish miners, 



" they frequently use bruising machines, carrying 150 librae of iron." This combination 

 of fire and vinegar he again refers to (xxiil, 27), where he dilates in the same sentence on the 

 usefulness of vinegar for breaking rock and for salad dressing. This myth about breaking 

 rocks with fire and vinegar is of more than usual interest, and its origin seems to be in the 

 legend that Hannibal thus broke through the Alps. Livy (59 B.C., 17 a.d.) seems to be the first 

 to produce this myth in writing ; and, in any event, by Pliny's time (23-79 a.d.) it had become 

 an established method — in literature. Livy (xxi, 37) says, in connection with Hannibal's 

 crossing of the Alps : " They set fire to it (the timber) when a wind had arisen suitable to 

 " excite the fire, then when the rock was hot it was crumbled by pouring on vinegar (infuso 

 " aceto). In this manner the cliff heated by the fire was broken by iron tools, and the 

 " declivities eased by turnings, so that not only the beasts of burden but also the elephants 

 " could be led down." Hannibal crossed the Alps in 218 B.C. and Livy's account was 

 written 200 years later, by which time Hannibal's memory among the Romans was generally 

 surrounded by Herculean fables. Be this as it may, by Pliny's time the vinegar was 

 generally accepted, and has been ceaselessly debated ever since. Nor has the myth ceased 

 to grow, despite the remarks of Gibbon, Lavalette, and others. A recent historian (Hen- 

 nebert, Histoire d' Annibal 11, p. 253) of that famous engineer and soldier, soberly sets out to 

 prove that inasmuch as literal acceptance of ordinary vinegar is impossible, the Phoenecians 

 must have possessed some mysterious high explosive. A still more recent biographer swallows 

 this argument in toto. (Morris, "Hannibal," London. 1903, p. 103). A study of the com- 

 mentators of this passage, although it would fill a volume with sterile words, would disclose 

 one generalization : That the real scholars have passed over the passage with the comment 

 that it is either a corruption or an old woman's tale, but that hosts of soldiers who set about 

 the biography of famous generals amd campaigns, almost to a man take the passage seriously, 

 and seriously explain it by way of the rock being limestone, or snow, or by the use of explosives, 

 or other foolishness. It has been proposed, although there are grammatical objections, that the 

 textisslightly corrupt and read »«/osso acuta, instead of infuso aceto, in which case all becomes 

 easy from a mining point of view. If so, however, it must be assumed that the corruption 

 occurred during the 20 years between Livy and Phny. 



By the use of lire-setting in recent times at Konigsberg (Arthur L. Collins, 

 " Fire-setting," Federated Inst, of Mining Engineers, Vol. V, p. 82) an advance of from 5 to 

 20 feet per month in headings was accomplished, and on the score of economy survived the 

 use of gunpowder, but has now been abandoned in favour of dynamite. We may mention 

 that the use of gunpowder for blasting was first introduced at Schemnitz by Caspar Weindle, 

 in 1627, but apparently was not introduced into English mines for nearly 75 years afterward, 

 as the late 17th century English writers continue to describe fire-setting. 



