Proceedings of the Annual Meeting
Author | : Lake Superior Mining Institute |
Publisher | : Rarebooksclub.com |
Total Pages | : 80 |
Release | : 2013-09 |
ISBN-10 | : 123004700X |
ISBN-13 | : 9781230047003 |
Rating | : 4/5 (0X Downloads) |
Book excerpt: This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...tube, by testing tubes at known angles according to the method described by Mr. Jopling. Figure 4 shows a curve for i Y%" tubes. It will be noted that for these larger tubes the correction is only 3% at 45, which is the maximum. The angle can be read to y2 and I feel certain that the results of tests for inclination can be relied upon to within 1. To determine the course of the hole, the tube is placed in the goniometer with the graduated circle set at 0 so that the tube is vertical. If the inclination of the hole is steep the tube is twisted until the etching shows the dip to be either directly toward or away from the eye; that is, until the crossthread bisects the ellipse etched on the glass. If the inclination is shallow it is more accurate to twist the tube so that the dip is to the right or left of the observer and in the plane of the graduated circle. The goniometer is next placed on a protractor so that the tube comes vertically over the center, and by sighting down over a straight edge placed in line with the North and South points marked on the tube the point of the compass towards which the hole dips may be determined. Figures 3 and 5 show tubes with acid, gelatine, compass, and North and South points marked, just as they are taken from the drill hole. I intend to have another goniometer made with-horizontal circle to measure the course as well as vertical circle for the inclination, but have not bad an opportunity to do so as yet. We have found the method described above very successful, and two tests at the same point almost always agree. When this is not the case more tests are made and so far we have always been able to ascertain which are wrong. We have made tests at a depth of 2000', but it would probably be difficult...