Mines of Saxo7it/, 387 



them. He considers in the examination of each soil, 1st, ths 

 nature of tlie principal rock, and the interes^tiug geognostic facts 

 which it presents ; 2d, the sidord'amfe loiih which this rock 

 contains ; 3d, the veins (filons) which pass through it. 



M. de Bonnard's arrangement confines him to the indications 

 presented by the external form of the ground; and it has the ad- 

 vantage of presenting groups very clearly limited, and which dif- 

 fer from each other, either by the system' of rock which is predo- 

 minant, by the general inclination of these rocks, or bv the nature 

 of the nucleus around which they are grouped. Speaking of the 

 anomalies which he had observed in the system or group" of the 

 east, M. de Bonnard thus expresses himself: " I ought to men- 

 tmn that the inclinations indicated are not without exception. 

 Some anomaliesare presented, for example, in theenvironsof Dip- 

 poldswalde, Glasshute, fee. ; others take place even in the vicinity 

 of the granitic nucleus. The inclinations which are remarked in 

 these places, different from those presented as general, may be- 

 long to some prolongation or hidden branch of the nucleus, or to 

 other causes which are unknou-n to us : but it appears to me that 

 they cannot shake the results drawn from the general observation 

 of the observed arrangement of the soil." 



M. de Bonnard speaks highly of M. Daubuisson's work on the 

 mines of Freyberg, all now at vvork : they are upwards of 150 in 

 number, and occupy .5000 workmen, pi oducing annually 50,000 

 marcs of silver, a quantity of lead varying from 3000 to 10,000 

 quintals, and rarely more than from I'OOto 200 quintals of cop- 

 per.^ He also mentions, as a new a..d remarkable undertaking, the 

 navigable and subterraneous canal called Fnederick-henno-slQllu. 

 They have been obliged to dig this canal from Dorrenthal to 

 Pfappenrode, a length of 11 00 toises, to find the waters of a river 

 (the Biel-i) in order to unite them with those which give motion 

 to the machinery of Freyberg. It is intended to open another, 

 also subterraneous, of 1600 toises, with the same view. Much 

 more time will be requisite to finish these useful works ; but they 

 will give the possibility of working the existing mines of Frey- 

 berg to more advantage, and of re-opening others which have been 

 abandoned for want of the means of clearing them of water. 



The |)rineipal shaft of the mines of Altenburi; has been made 

 by blasting in the stanniferous rock. The working always took 

 place by blasting, by means of huge excavations, which were en- 

 larged without any precaution, until in 1620 there was a general 

 falling in of all the workings. This disaster produced an excava- 

 tion of nearly 600 feet diameter by 300 feet in depth. They have 

 continued to work by blasting in the parts which remained solid, 

 and they have not given up the plan of chambers of large dimen- 

 •ions. These are dug in the parts most abounding in tin j those 



B b 2 wliich 



