Mohave County miner., 1906-02-24
Successful Mining.

local conditions. Many costly eXperl- ments might have been avoided by at tention to the experiences of others who had tackled the same problem.
 Engineers, as well as investors, will do well to learn all that the history of the district where they are operating has to teach them. Such knowledge is the only sure foundation for pro- gress and success. The Engineering and Mining Journal says:
 Many large losses that have been experienced in mining and metallurgi- cal enterprises are directly traceable to imperfect study and disregard of local experience, i. e., the practice that has been evolved in the particular district as the result of gradual, and usually timid and tentative experiment tation. The practice may appear de- fective and backward to the new-com- CT, experienced in other districts, and he is prone to jump at the conclusion that it can be improved. This is ire quently the case; but also it is ire quently the case that the apparently defective and backward practice has a reason for its status, and the attempt to improve it fails because of unknown or misunderstood conditions net taken into account.
 Thus, in the Joplin district, Missouri, the mining and milling methods six years ago were apparently very crude. Their crudity impressed itself strongly on engineers visiting the district in behalf of outside capitalists who be- came interested there at about that time. Improvements based on exper- fence in other mining districts were promptly determined upon, and were carried out, with unsuccessful results, because of failure to recognize the pe- culiar conditions and the fact that the local practice had been developed in conformity with them. Since that time many improvements have been consummated in the district, and en- gineers with experience gained else where have been considerably instru- mental in effecting them. Their use fitness has been, however, in applying outside experience to that gained by practically working in the district it. self, affording a thorough knowledge of its peculiar conditions.
 Errors of this kind are ascribable to two causes: l. Imperfect study of the local conditions; and, ,, willful dis regard of them. The local conditions may, indeed frequently do, involve some subtle factors, such as character istics of the miners and millmen, which can be understood only by thorough acquaintance with them; or features of climate which may not be properly ap- preciated in brief experience; or misconception of the character of the ores, the nature of the deposits, and the markets in too brief a study. Will ful disregard of the local conditions, on the other hand, implies no study of them at all. Examples of such mis- takes are to be found in almost every mining district. Plants are erected on the designs and specifications of engineers who have never been in the district, or have gone there only to ex- anime the topography of the ground. Plants are erected to try some new scheme, as, for example, a concentrat- ing mill with fine crushing and tables in district where the experience of thirty years had demonstrated the efficiency of coarse crushing and jig ging: of the erection of Joplin mills in districts where experience had shown the necessity for closer treat ment of the ore. All of these experi- ments were, of course, failures.
 Every district in which mining and milling is practiced for considerable period of time developes local exper- fence in the extraction and treatment of its ores, which is strictly in con formity with the conditions, because the conditions themselves, to large extent, establish the experience. I'm proveInents are made as experience is gained, usually as the result of exper- iments tried cautiously and tentatively always with patch for retreat. The local practice may be defective and capable of immediate improvements; but the engineer who undertakes it must be sure of his ground. He should not disregard the local practice be- cause of its apparent inefficiency, but should examine and study the causes which have determined it. There will