352 M. Mohs o?i the Discover i' of Useful Minerah. 



but the examination of the question as to whether the im- 

 portance of a repository would warrant further proceedings, 

 requires that I should devote a few remarks to it. 

 ; In order to carry such investigations into effect, we must 

 select a situation where we can reach the repository by 

 experimental trials (versiichbauen). Mere experimental trials 

 can be made at points where we have no intention what- 

 ever of carrying on mining operations, for they only allow us 

 to ascertain sufficiently the mining value of the repository. 

 For if we are convinced of this, it is perhaps of little conse- 

 quence if we can employ the already made trials in actual 

 mining operations or not, and this undoubtedly requires a 

 careful examination, so that we may not, by ill-judged eco- 

 nomy, afterwards cause inconvenience and annoyance, which 

 cannot be got rid of without great and continued labour and 

 outlay. A position which is suited to the examination of the 

 mining value of a repository must admit of the repository 

 being traversed by levels and shafts. What is necessary for 

 such purposes requires no further remark at present, except 

 that, if local circumstances do not otherwise determine the 

 point, we shall generally attain our object better by means of 

 levels in the case of beds, and by shafts in the case of veins, 

 inasmuch as the former are not so variable at different depths 

 as the latter ; and that all these trials must be made upon the 

 repository itself, and not across the rocky mass in which it is 

 contained, if very peculiar circumstances do not call for the 

 contrary ; for, by means of a bore in the repository, we be- 

 come acquainted with it throughout its full extent, while, by 

 cutting across the rock, we only ascertain its nature at one 

 point, and are therefore obliged to inform ourselves respecting 

 the remainder by other operations. 



After we have met with a bed of such a nature that we may 

 hope for productive operations, we must not neglect to search 

 for other similar beds in the same district ; for experience 

 teaches us, that not unfrequently several rich repositories of a 

 like nature occur at short distances from one another, and the 

 investigation causes the least expenditure of time and money, 

 when we are at the same moment engaged with similar objects. 

 Whether the repository which has been discovered, is an irregu- 

 lar mass (ein Uegender Stock) of very considerable or of smaller* 



