Determination of the difference of Longitude between Toledo and Columbus, Ohio, by electric signals for comparisons of time, January 25th, 1859. Sidereal Chronometer No. 2557, fast, of Columbus sidereal time (at 7h. 09m. 52s. sidereal time), 1h. 04m. 32s.25. Rate per sidereal day, + 4s.473; or per sidereal hour, + Os.1864. Mean Solar Chronometer No. 141, slow, of Toledo mean solar time (at 10h. 47m. 58s. mean time), 20m. 58s.61. Rate Os.0208. per mean solar day, - Os.500; or per mean solar hour, 1st.-Toledo signals recorded at both stations. 1st Mean. Electric signals sent from Toledo to Columbus, Ohio, 2d.-Columbus signals recorded at both stations. h. m. S. Toledo correct at Toledo mean solar time of Chronometer No. 141. Toledo reduced sidereal time of Columbus signals. h. m. S. h. m. s. h. m. S. Result:-Columbus Observing Station, east in longitude, of Toledo observing Station, by a mean of the two sets of signals, Difference of Longitude by each signal.Columbus east of the meridian of Toledo. h. m. s. 0 02 09.02 0 02 09.01 0 02 09.00 0 02 09.01 0 02 09.01 0 02 09.01 0 02 09.01 0 02 09.02 - 0 02 09.015 Brought forward, h. m. S. ·0 02 09.01 Reduction to the dome of the State Capital, Dome of the State Capital is east, in longitude, of Longitude of Toledo observing station, Result-Longitude of the dome of the State Capital at Columbus, Ohio, west of the meridian of Greenwich, Equal, in arc, to Latitude of this dome, as before given, 5 32 00.52 83° 00' 07''.8 39° 57' 43".2 N. VERIFICATION OF THE POSITIONS OF MICHIGAN CITY, INDIANA, AND MADISON, WISCONSIN. The approximate positions of these stations were given in our previous paper, printed in Vol. VI. of the Society's Proceedings; the first numbered as Station II., and the other as Station VI. See pp. 363 to 365, and 385 to 388 of that volume. We have since had opportunities for testing the results, then reported, by more reliable observations, which we will now give. II. MICHIGAN CITY, INDIANA. Station. The centre of the public square, bounded on the north by Michigan street, on the south by Fourth, on the east by Franklin, and on the west by Washington street. By a survey made with the theodolite and chain,-the true azimuths of the courses being determined from four azimuths of Polaris, 2 by direct observation, and 2 others by reflection from the horizon of quicksilver, on the 17th May, 1859, with the times by the sidereal chronometer,—we find that this new station is S. 11° 15′ 49′′ E., (true) and distant 1717 feet from our station of June 21st, 1858. Hence the reduction from the station of 1858 to that of 1859, at the centre of the aforesaid public square is, in latitude, 16".64, and in longitude 4".41 in arc, = 0s.294 in time. From the centre of the public square, to the station where Captain Andrew Talcott observed in 1833, as pointed out to us by Herman Lawson, Esq., attorney at law, who was here at that time and still resides here, is N. 12° 05′ 25′′ W., (true) and the measured distance is 227 feet. Hence the reduction from our new station at the centre of the public square to Talcott's station is, in latitude, +2".19, and in longitude +0′′.63 in arc, Os.04 in time. The positions of other points in relation to our observing stations, were also fixed by our survey, and will be given hererfter. It will be remembered that the position of our station of June 21st, 1858, was stated, in our former paper, to be approximately, as follows, viz. (See Vol. VI. page 363.) Latitude, Longitude, west of Greenwich, 41° 43' 25" N. 5h. 47m. 37s.41 of This was the result of a few observations made within the space one hour and forty minutes, on that night, and a series of telegraphic signals for comparing the longitude with the meridian of Chicago. A reduction of the above determination, to our station of 1859, gives the position of the centre of the public square, as follows, viz.Determination 1st, of June 21st, 1858. Latitude, Longitude, west from Greenwich, 41° 43' 08".36 5h. 47m. 37s.12 We will now give the observations made in 1859, and the results, as follows, viz. At the centre of the Public Square in Michigan City, Indiana. 1st. The Latitude. 1859, May 17th. By 14 circum-meridian altitudes of a Virginis, south, combined with 17 altitudes of Polaris, north: latitude of station, 1858, June 21st. By 10 circum-meridian altitudes of Libræ, south, combined with 5 altitudes of Polaris, north, reduced from the old, to this station, as already shown, Result adopted-Latitude of the centre of the Michigan City Public Square, 2d. Observations for the Time. 1859, April 28th. Sidereal chronometer No. 2557, fast: By 10 observations on Bootis, east (at 12h. 11m.) By 10 observations on a Coronæ Borealis, also east (at 11h. 44m.) m. S. 1 31 05.20 1 31 05.33 By 10 observations on 3 Geminorum, west (at 11h. 30m.) Result-Chronometer No. 2557, fast of sidereal time for this station (at 11h. 29m.) +1 31 05.26 +1 31 05.29 +1 31 05.27 The above result for the Michigan City time, combined with the observations made on the 27th and 29th of April, for the time at Chicago, and the following telegraphic signals, give us a second determination of the longitude of Michican City, viz.- Determination of the Difference of Longitude between Chicago and Michigan City, Indiana, by electric signals for comparisons of time, April 28th, 1859. Sidereal Chronometer No. 2557, fast, of Michigan City sidereal time (at 12h. 47m. 47s. sidereal time), 1h. 31m. 05s.63. Rate per sidereal day, + 6s.669; or per sidereal hour, + 0s.2775. Mean solar Chronometer No. 141, slow, of Chicago, mean solar time (at 10h. 18m. 32s. mean time), 4m. 41s.32. Rate per mean solar day,· Os.007. Os.17; or per mean solar hour, 1st.-Chicago signals recorded at both stations. 1st Mean. Electric signals sent from Chicago to Michigan City, 0 02 53.49 2d.-Michigan City signals recorded at both stations. Difference of Times of signals given at Michigan City by sidereal Chronometer No. 2557. Times of Michigan City signals as noted at Chicago by mean solar Chronometer No. 141. S. h. m. s. h. m. S. h. m. s. h. m. s. 10 27 21.32 12 53 44.82 12 56 38.32 Result:-Centre of public square in Michigan City, east in Longitude of Chicago Station No. 3, Determination 2d. Longitude of the centre of Public Square at Michigan h. m. s. 0 02 53.50 0 02 53.50 02 53.49 02 53.48 0 02 53.49 0 02 53.49 - 0 02 53.49 +5 50 31.20 5 47 37.71 I was obliged, on the 17th of May, 1859, to go again to Michigan City, on public duty, and this visit enabled me to obtain a third result for the longitude of this place, as follows, viz. 1859, May, 27th. At the same Station. Sidereal chronometer No. 2557, fast: By 13 observations on ẞ Geminorum, h. m. S. By 13 observations on a Coronæ Borealis, east (at 12h. 02m.) Result-Chronometer No. 2557, fast of sidereal time for this station (at 12h. 12m.) +1 33 29.28 |