Determinations of Gravity at Stations in Pennsylvania 1879-1880: Appendix No. 19--Report for 1883, Issue 19

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U.S. Government Printing Office, 1884 - Gravity - 58 pages
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Page 7 - and York, which are marked 3-4 and 7-8, have, at my request, been micrometrically examined by Assistant Edwin Smith, to determine the distance of the edges from the plane of the bearings. He obtained the following results: Knife 3—4. At end marked 3, 122 . At end marked 4, 125^. Knife 7—8. At end marked 7,
Page 6 - It was intended to conduct the operations as at Allegheny; but various difficulties compelled me to support the pendulum on the Repsold tripod, as at my European stations. The brass footrests were placed directly upon the hard clay floor of the cellar. The old knives which had been used in Europe and in the stations at
Page 5 - OF GRAVITY AT EBENSBURGH. Ebensburgh is the chief (though not the principal) town of Cambria County, Pennsylvania, in the Allegheny Mountains. The observations were made in the house and grounds of Mrs. Frances S. McDonald, on Centre street. The place is shown on the county map by Beers (1867), where the house has marked under it
Page 7 - support when the nuts in question were hand-tightened and when they were wrenched. The values given on page 388 of the Report have been used in the reductions, and the periods have accordingly received the following corrections: Heavy end down. Heavy end up. First four days -.0000832 -.0000362 Last four days -.0000895 -.0000390 The knives used
Page 11 - Applying as for Allegheny the corrections for elevation and latitude, we have Seconds pendulum at Ebensburgh 0.9930244 Elevation +1827 Latitude . —21399 Corrected to equator and sea-level 0.9910672 In the tables appended to the edition of this Appendix which has been published separately are given the details of the work at Ebensburgh. III.-DETERMINATION
Page 4 - The experiments to determine the flexure of the support have already been published in the Coast Survey Report for 1881, pp. 375-377. The mean of the measurements of two observers shows that the flexure at the middle of the knife-edge, under a horizontal force equal to the weight of the pendulum, was
Page 9 - 18 +16.4 19 +16.3 19.... +16.9 20 ... +16.9 20 +21.5 21...' +17.5 Mean... +17.6 But these measures are uncorrected for the difference of temperature between the pendulum and the standard; and in point of fact the former carried no thermometer. We may assume that the result should have a correction of
Page 1 - It will be noticed that the oscillations were continued down to a small amplitude, but there seems to have been no increased error upon this account. Following the synopsis will be found a table of the errors of the partial swingings formed by intermediate transits, as shown on pages 502-503.
Page 5 - of the valley were taken into account. A topographical sketch of this vicinity is the most pressing need of the work at this time. The details of the work at the Allegheny Observatory are given in the tables appended to the edition of this Appendix, which has been published separately.
Page 14 - +25.5 +31.3 +30.0 Mean +28.6 These figures are uncorrected for the difference of thermometers on the pendulum and standard, because such correction would make the accordance of the measures much less good. We must assume the excess of length of the pendulum in the first position to have been

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