Obviously a very important feature of any mine must be its location, and the determination of this must always constitute the principal hazard in practical mining. Prospecting, or exploring for suitable mining sites, has been an important occupation for many years, and has in fact become a scientific one recently. Formerly mines were frequently stumbled upon by accident, but such accidental discoveries are becoming less and less frequent. The prospector now draws largely upon the knowledge of the scientist to aid him in his search. Geology, for example, assists him in determining the region in which his mines may be found, if it cannot actually point out the location for sinking his shaft; and at least a rough knowledge of botany and chemistry is an invaluable aid to him. It is obvious that it would be useless to prospect for coal in a region where no strata of rocks formed during the Carboniferous or coal-forming age are to be found within a workable distance below the surface of the earth. The prospector must, therefore, direct his efforts within "geological confines" if he would hope to be successful, and in this he is now greatly aided by the geological surveys which have been made of almost every region in the United States and Europe. An example of what science has done in this direction was shown a few years ago in a western American town during one of the "oil booms" that excited so many communities at that time. In the neighborhood of this town evidences of oil had been found from time to time--some of them under peculiar and suspicious circumstances, to be sure--and the members of the community were in an intense state of excitement over the possibility of oil being found on their lands. Prices of land jumped to fabulous figures, and the few land-owners that could be induced to part with their farms became opulent by the transactions. An "oil expert" appeared upon the scene about this time--just "happening to drop in"--who declared, after an examination, that the entire region abounded in oil. He backed up his assertion by offering to stake his experience against the capital of a company which was formed at his suggestion. Before any wells were actually started, however, a prudent member of the company consulted the State geologist on the subject, receiving the assurance that no oil would be found in the neighborhood. Strangely enough the word of the man of science triumphed over that of the "oil expert," and although some tentative borings were made on a minor scale, no great amount of money was sunk. It developed afterwards that the evidences of oil found from time to time had been the secret work of the "expert."