By comparison-Chronometer No. 141 was slow of mean solar time for this station (at 9h. 15m. mean time) P. S. The following determinations of the Chicago time (Nos. 29 and 30) were made after this paper was presented, with reference to a second determination of the longitude of the City of Rock Island, viz: 29th. 1859, July 28th. At Chicago Station No. 3. h. m. S. Bootis, west (at 17h. 44m.) + 1 45 30.94 +1 45 31.40 Result--Chronometer No. 2557, fast of sidereal time for this station (at 17h. 55m.) By comparison-Chronometer No. 141, was slow of mean solar time for this station (at 9h. 30m. mean time) +1 45 31.17 30th. 1859, July 31st. At the same Station. fast: 5 03.37 h. m. S. Sidereal chronometer No. 2557, Result-Chronometer No. 2557, fast of sidereal time for this station (at 17h. 53m.) By comparison-Chronometer No. 141, was slow of mean solar time for this station (at 9h. 16m. mean time) +1 45 53.99 5 05.63 This ends the series of time-observations made at Chicago during the period included in this paper. Rates of the Chronometers. The rates of the chronometers during the period included in this paper, were as follows, viz: *The rates from June 20, to July 21, 1858, are given at page 362 of Vol. VI. of the Society's Proceedings. 46 The above table shows clearly that the rate of sidereal chronometer, No. 2557, was accelerated when it was allowed to remain at rest, and that it was retarded (the rate of gaining diminished) by the effect of travelling, independent of the effect of change of temperature. 2d. Rates of Mean Solar Chronometer No. 141. We will now give the observations that were made at the station. whose positions were to be determined, following the order in which they are enumerated in the beginning of this paper. VII. ASHTABULA, OHIO. Station The centre of the Public Square. 1st. Observations for the Latitude (Approximate) 1858, Aug. 6th. The sky to the north was cloudy, and that to the south was still more so, which prevented observations, as satisfactory as could be wished, for the latitude. It was, however, obtained near enough for computing the observations on East and West Stars for the time and longitude, as follows, viz: By 14 circum-meridian altitudes on Cephei north, combined with 2 observations (circum-meridian) on Altair ( Aquilæ,) and 4 on Pegasi, both south;-latitude 2d. Observations for the Time. Sidereal chronometer No. 2557, fast: 41° 52' 04" N. 2d Set. After the Signals. By 8 observations on a Cygni, west (at 24h. 29m.) By 11 observations on a Auriga (Capella) east (at 25h. 19m. or 1h. 19m. of Aug. 7th, sidereal) 2d Result. After the Signals-Chronometer No. 2557, fast (at Oh. 54m. of Aug. 7th, sidereal) 36 34.58 36 35.11 36 34.85 + 36 34.85 Result adopted-Chronometer No. 2557, fast of sidereal time for this station (at 22h. 34m. of Aug. 6th, sidereal) 3d. For the Longitude. + 34.56 The above result, for the Ashtabula time, compared with the timeobservations at Chicago, of the 4th and 12th of August, to obtain the rate of mean solar chronometer No. 141, and applied to the following telegraphic signals, gives the difference of longitude between those two places, and the longitude of Ashtabula west of the meridian of Greenwich, as follows, viz: The rate of the sidereal chronometer, from the period of its determination this night, back to the period of each signal, is deduced, in this instance, from the two sets of time-observations made this night. The great elapsed time here, being 4h. 39m., seemed to justify this. Determination of the difference of Longitude between Chicago and Ashtabula, Ohio, by electric signals for comparisons of time, August 6th, 1858. Sidereal Chronometer No. 2557, fast, of Ashtabula, sidereal time, (at 21h. 18m. sidereal time,) 36m. 34.04s. Rate per sidereal day, + 38.00; or per sidereal hour, + 0s.125. Mean Solar Chronometer No. 141, slow, of Chicago, mean solar time, (at 11h. 49m. mean time,) 4m. 31s.02. Rate per mean solar day, + Os.455; or per mean solar hour, + Os.01896. 1st.-Chicago signals recorded at both stations. h. m. 8. 21 18 22.10 20 51 00.72 0 27 21.38 21 20 52.59 20 53 31.13 0 27 21.46 21 45 16.54 21 17 55.12 0 27 21.42 21 48 17.04 21 20 55.61 0 27 21.43 1st Mean.-Electric signals sent from Chicago to Ashtabula 0 27 21.422 |