The circumstances of gold-mining on the Rand have, therefore, features quite distinct from those of quartz-reef, alluvial, or other kinds of mining, and approximate to those of coal winning, especially in the matter of the depth and regularity of the conglomerate formation. Its peculiarities have created a method of mining, the outcome of costly experiment, experience, and skill, which will remain a lasting asset to future ages.
The future gold production of the Rand mining industry is a subject which enchains the attention alike of the investor and the curious. In approaching the subject of the unexploited gold contents of the banket formation, figures are handled which simulate the fabulous, and almost excuse the disbelief with which all such estimates are received in some quarters. Confirmation of the approximate correctness of the computations may, however, be obtained in two ways: firstly, from the past yield of the gold-fields in the seventeen years since their start; and secondly, from the verification of former prognostications which subsequent outputs have furnished. So far as regards the former, the fact of the production of £81,000,000 of gold since the start of the industry up to now, under well-known circumstances is, in the first place, proof positive that the gold exists; and, in the second, affords inferential grounds for assuming that, given at all similar circumstances, mining operations will yield like results. This is, of course, taking the lowest ground, for it is indubitable that the circumstances will not be alike, but vastly improved, in which case the value of the results will be proportionately enhanced. As to the confirmation which results from the verification which later outputs have furnished, both of the trustworthiness of the bases on which former forecasts were made and of the prognostications themselves, there may be instanced the forecasts of such early computators as Mr. Hamilton Smith, Mr. C. D. Rudd, and others. The former, in 1892, in a report on the future production of the Rand fields, made by request of Messrs. Rothschild, adventured an opinion which is worth quoting textually. He said: "With the active and energetic men who have this industry in hand, and always supposing that the foregoing theories be correct, in _three or four years from now_ the producing power of the mines and their reducing works will, I think, be increased to an output of _five or six million tons of ore per annum_, worth a gross yield of over £10,000,000. At this rate the available supply of ore, as conjectured above, will last for more than thirty years."