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Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve ...

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve ...

Excerpt from Drilling for Placer GoldThere is yet another angle to the situation. In the event that preliminary work prompts a complete campaign of evaluation, the Keystone is absolutely necessary. And when the dredge is finally completed and at work, the Keystone has not outlived its usefulness. Modern practice suggests t the continued use of the drill in front of the dredge, blasting hard ground, determining the boundaries of barren areas, c...

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Excerpt from Drilling for Placer Gold The Keystone Drill, as universally used, is not an instrument of precision. Gold particles are not distributed with mathematical symmetry. One drill hole to an acre in ground that is 50 feet in depth only yields for examination part of the whole! Ordinary common sense and care on the part of the operator and panner are sufficient to insure acceptable field work. Meticulous precision or elaborate core meas...