Publications of the Washburn Observatory of the University of Wisconsin Volume 2 (Paperback)

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. 1884 edition. Excerpt: ...is therefore 1.310 inches, and the center of the micrometer screw is therefore 0.010 from the centre of the circle through the legs. OBSERVATIONS. The observations consisted in measurement of the heights of two brass cylinders with plane ends, the property of Prof. Harkness, U. S. Navy, and kindly lent by him. The large cylinder is denoted by A; the small cylinder by B. The logarithms of the heights of the two cylinders in inches are respectively 9.41486 and 9.09787. The corrections to the heights of A. and B. for temperature have been neglected, as being almost inappreciable. The whole range of temperture was less than 7." The zero of the spherometer was determined by taking readings upon a true plane of metal. The observations were made by taking a set of ten readings upon one of the cylinders, then a set of ten upon the plane surface, and then a set of ten upon the other cylinder, so that there are thirty measures in a complete set. Table I contains a summary of these measures. The columns headed A and B contain the heights of the two cylinders in terms of a revolution of the spherometer screw. Each value as there given is the mean of ten measures. See Washington Astronomical Observations for 1877, Appendix I. page 6. Table II contains the probable error of the measures from which the results in Table I are derived. TABLE II. From the data in Table I and the height of the cylinder in inches, the individual determinations of one revolution of the spherometer screw in inches are deduced. These follow, in Table III. In the course of the measures on cylinder B it was discovered that the two plane surfaces were not parallel to each other at all points. The results derived from the measures on B are assumed to be entitled to half...