CONCLUDING REMARKS. 751 



COXCLUDIXG EEMAEKS. 



In the preparation of this report, I have been actuated by many considerations which 

 have to a great extent determined its character and contents. In the first place, the 

 space which can justly be devoted to the Lead region in a report on the entire state is 

 necessarily small, and involves a judicious selection of the material collected and pre- 

 pared. 



In the course of my examinations in the Lead region, I have found in all places, and 

 among all persons connected with the mining interests, a general expression of a desire 

 for information in regard to the condition of the mining industry in those portions of 

 the Lead region more or less remote from the ones in which they reside. To furnish 

 such information is undoubtedly a legitimate object of a work of this kind, and to it, 

 therefore, I have devoted about two-thirds of this report, reserving the remainder for 

 the geological and topographical examinations contemplated by the law. 



Among other subjects which I have been obliged to omit is the much-argued ques- 

 tion of mining in the Lower Magnesian limestone. No discussion of thia question can do 

 it justice which does not take into consideration the origin of the crevices, and the man- 

 ner of deposition of the ores and associate minerals contained in the mines now operated, 

 since these questions are the only premises from which we can derive any reliable con- 

 clusions. 



The discussion of this question would have occupied more space in the report than I 

 felt justified in devoting to theoretical questions, at the expense of what appeared to me 

 to be important practical facts. 



The subject of drainage in our mines is one of great importance; at present it is ef- 

 fected by pumping, and by levels or adits. Pumping is at best but a temporary expe 

 dient, and when steam is employed it is a costly one ; it effects the drainage of only a 

 comparatively small area, and when the pump ceases to work, water immediately returns 

 Expensive pumping operations are only warranted where large bodies of ore are known 

 to exist, within a small area of ground. 



On the other hand, the drainage effected by a level is permanent and extensive, al- 

 though the original outlay of capital is large. Our mines have now been worked so long 

 that it is known in each mining locality how many ranges have been worked to the nat- 

 ural water level, and the comparative value of the veins of ore left in them when aban- 

 doned. With this foreknowledge it is not difficult to arrange a level that will not only 

 drain the previously known ranges, but will also make it possible to work any others 

 which may afterwards be discovered in its vicinity; a system which is further favored by 

 the well known parallelism of the ranges. 



The stratum in which levels can be most rapidly excavated, and with the least ex- 

 pense, is the upper or thin-bedded portion of the Blue limestone (Trenton). There are 

 no interstratified beds of clay above it, and usually nothing to prevent the drainage of 

 all the Galena limestone; but as the strata sometimes contain slight flexures, it is not 

 always possible to drive a level in the same formation. Levels driven in this, the upper 

 pipe-clay opening have the additional advantage of proving one of the most produc- 

 tive openings known in the Lead region. 



Judging from the number of levels which have been excavated, and the success which 

 has usually attended them when completed, the system of mining by levels seems to 

 offer the safest field for the employment of capital. 



The recent inventions and improvement in pneumatic, or compressed air drills, and 

 in mining explosives, such as dynamite and rendrock, are daily rendering the excava- 

 tion of levels a much less laborious task. 



