2d.-Dunleith signals recorded at both stations. 2d Mean. Electric signals sent from Dunleith to Chicago, Result:-Dunleith Station No. 1, is west, in longitude of Chicago observing Station No. 3, by a mean of the two sets of signals, Longitude of Chicago observing station No. 3, west of the meridian of Greenwich, +5 50 31.20 Determination 1st. Longitude of Dunleith observing station, west of the meridian of Greenwich, 6 02 35.88 had to the time For the second determination, reference must be observations at Dunleith, of the 22d of February; and to those at Chicago, as before stated, of the 20th and 23d of February, and to the following telegraphic signals, viz.— Determination of the difference of Longitude between Chicago and Dunleith, Illinois, by electric signals for comparisons of time, Sidereal Chronometer No. 2557, fast, of Dunleith sidereal time, (at 10h. 00m. sidereal time), 1h. 38m. 20s.51. Rate per sidereal day, + 5s.308; or per sidereal hour, + 0s.221. Mean solar Chronometer No. 141, slow, of Chicago, mean solar time, (at 12h. 01m. 42s. mean time), 4m. 42s.92. Rate per mean solar day, 08.03109. Os.746; or per mean solar hour, h. m. s. 11 57 00 h. m. 8. 12 00 00 1st Mean. Times of Chicago signals, as noted at Dunleith by sidereal Chronometer No. 2557. h. m. s. Chicago Dunleith correct sidereal time sidereal time of of Chicago Difference of Longitude by each signal.Dunleith west of the meridian of Chicago observing station No. 3. Chicago 12 01 42.92 11 38 22 10 00 01.50 10 12 05.91 2d.-Dunleith signals recorded at both stations. h. m. s. 0 12 04.41 0 12 04.41 0 12 04.41 h. m. S. h. m. S. Result: Dunleith station No. 2, is west in longitude of Chicago Longitude of Chicago Station No. 3, Difference of Longitude by each signal.Dunleith west of the meridian of Chicago observing station No. 3. h. m. s. 0 12 04.42 0 12 04.43 0 12 04.43 0 12 04.44 Longitude of Dunleith observing station, west of the meridian of Greenwich, by this 2d determination of Feb. 22d, 1859, Determination 1st. 6 02 35.62 By the observations and signals of February 21st, as above given, Result adopted-Longitude of the Dunleith observing station, west of the meridian of Greenwich, by a mean of the two determinations, Equal, in arc, to Latitude of this station, as before given, Result-By the measured offset and azimuth, from this station, given at the beginning of this article XI. the most northern cupola on the top of the ticket-office of the rail road depot, is in— Latitude Longitude, west of Greenwich, Equal, in arc, to 42° 29′ 42'.5 N. 6h. 02m. 35.8s. 90° 38' 57" W. Dunleith is at the north-western terminus of the Illinois Central Rail Road, on the east bank of the Mississippi river, and occupies the site of the old Indian village of Sinipi. Extensive earth works, consisting of mounds thrown up in oval forms by the tribe which formerly resided here, still exist at Dunleith, in a state of perfect preservation. We had no time to devote to them that minute exploration which would no doubt show their contents to be similar to those of the numerous Indian mounds examined by Professor J. A. Lapham, of Milwaukee, and described in his valuable memoir, published in the year 1855, by the Smithsonian Institution, under the title of "THE ANTIQUITIES OF WISCONSIN." = The position of Sinipi (now Dunleith), is laid down on the map of Nicollet, in latitude 42° 36′ north, and in longitude, west of the meridian of Greenwich, 6h. 02m. 38.6s. 90° 39′ 39". Nicollet did not, however, make any astronomical observations at this or any other point on the Mississippi, between the " Head of the Upper Rapids, below Port Biron and Parkhurst," and "Prairie du Chien. We infer from his report, that the extensive reach of the Mississippi, from latitude 41° 36′ 08′′ to latitude 43° 03′ 06'', was laid down on his map, from the surveys made under the direction of the General Land Office of the United States, checked by his observations made at the two extreme points above mentioned. (See his table of Geographical positions, page 123 of Senate Doc. No. 237, of the 26th Congress, 2d Session.) Nicollet's longitude, thus derived, agrees very closely with ours; but in latitude he is 6' 18" 74 miles north of us. Dubuque is placed equally out of position, in latitude, on his map; but it appears to be very correct in longitude. = In the last map issued from the War Department of the "Territory of the United States, from the Mississippi to the Pacific Ocean," these cities are laid down correctly in longitude, but they are placed four minutes, 4 miles too far north in latitude. = The boundary line between the State of Illinois on the north, and the State of Wisconsin on the south, is defined to be along the parallel of 42° 30' of latitude. We regret that we had not time to make a connection, by survey, from our astronomical station at Dunleith, to the stone monument on the east bank of the Mississippi river, erected to mark the western terminus of this boundary line. From a close reconnoissance, however, we infer that the latitude of this monument is about 42° 30′ 20′′, and hence, that the monument is placed about one-third of a mile too far to the north. XII. DUBUQUE, IOWA. This city is situated on the west bank of the Mississippi river, opposite to Dunleith, Illinois. From a reconnoissance and bearings observed from several points in Dunleith, based on the latitude and longitude of our Dunleith station, as already given, we are enabled to give the approximate position of Dubuque as follows. The distance between the two points being, in a direct line, not more than one and one-fourth mile, viz. Latitude, CENTRE OF THE CITY OF DUBUQUE. Longitude, west of the meridian of Greenwich, 42° 29' 55" N. 6h. 02m. 40s. 90° 40' 00" XIII. FULTON, ILLINOIS. This city is situated on the east shore of the Mississippi river, 136 miles west of Chicago, by the track of the Chicago, Dixon, and Iowa Air Line Rail Road, of which it is, at present, the western terminus. Immediately opposite is the city of Lyons, situated on the west shore of the Mississippi. Observations were made at both places, and the observing stations were connected by a triangulation and azimuths, derived from an observation on Polaris (« Ursa Minoris). From the astronomidal station at Fulton, to that at Lyons, is 3595.5 feet, on an azimuthal course of N. 68° 43′ W. Hence the Lyons station is 12.89 north of the parallel and + 44".29 in arc, + 28.95 in time, west of the meridian of the Fulton Station. We shall have occasion to use this difference of latitude in applying a common correction (-1.92 in the one case, and +1".92 in the other), to the observed latitudes of these two stations, in order to render the difference of their latitudes consistent with the result of the survey. The survey gave us, also, the longitude of the Lyon's Station, based on that of the VOL. VII.-I Fulton Station, derived from comparison by means of the two chronometers, with the longitude of Chicago. We now proceed to give the observations at Fulton :— Position of the Fulton Station.-From this station to the intersection of the middle of Base Street, with the middle of Cherry Street, is N. 53° 24′ 53′′ W. (true) and the distance is 302 feet. Hence the reduction in latitude is + 1'.71, and in longitude + 3".20 in arc, or +0s.214 in time. 1st. Observations for the Latitude. 1858, March 24th. By 19 circum-meridian altitudes of Polaris (lower transit) north, combined with 26 circum-meridian altitudes of a Virginis, south, Correction due to survey, connecting with the Lyons observing station, Latitude of station adopted, о 41 52 03.25 1.92 41 52 01.33 N. 2d. Observations for the Time. 1st. 1858, March 24th. Mean solar chronometer was fast of mean solar time at apparent noon: By 2 pairs of equal altitudes of the sun's lower limb, + 5m. 10.72s. By comparison-Chronometer No. 2557, was fast of sidereal time for this station at apparent noon (say at Oh. 14m. sidereal time) 2d. 1858, March 28th. Sidereal chronometer No. 2557, fast: By 10 observations on a Tauri, west, and 9 observa- Result-Chronometer No. 2557, fast of sidereal time for this station (at 9h. 35m. sidereal time) By comparison-Chronometer No. 141, was fast of mean solar time for this station (at 9h. 10m. mean time) +1 00 31.93 + 1 00 31.87 +1 00 31.90 + 5 07.94 |