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Longitude of Chicago observing station No. 3, west of the meridian of Greenwich,

Longitude of Erie observing station west of the

meridian of Greenwich,

Equal, in are, to

Latitude, as before,

0 30 09.715

+5 50 31.2

+5 20 21.5

80° 05' 22'.5 W.

42° 07' 54'.8 N.

My duties required me to return to Chicago immediately after completing the above observations. I arrived there on the morning of the 11th August. The night of that date was unfavourable for observations, which had to be deferred until the night of the 12th. This makes the elapsed time between the Chicago observations, which enter into the above determination of the longitudes of Ashtabula and Erie, from the 4th to the 12th of August; or 8 solar days, during which period we depend on the run of mean solar chronometer No. 141, in deducing those longitudes.

IX. TOLEDO, OHIO.

Station. By a true azimuth derived from observations on Polaris (a Ursa Minoris) with the theodolite, and a horizontal measurement with the chain, from this observing station to the point of intersection of the middle of Jefferson street, with the middle of Superior street, is S. 60° 14' 57" W., and the distance 141 feet.

1st.

Observations for the Latitude. 1858, August 13th.

By 5 circum-meridian altitudes of Pegasi, and 7 circum-meridian altitudes of a Pegasi, both south, combined with 14 observed altitudes of Polaris (a Urs. Minoris) north,

1859, January 24th. By 18 circum-meridian altitudes of Orionis, south, combined with 20 observed altitudes of Polaris, north,

By giving the 2d set twice the weight of the first, we

get

Result-Latitude of station,

о

41 39 02.85

41 39 01.97

41 39 02.26 N.

When the observations were made for the latitude on the night of August 13th, 1858, the sky to the south was so much clouded that no more observations could be made in that direction, for that object, than are above reported. The result then obtained agrees, however, well with that derived from the satisfactory set of observations made on the night of January 24th, 1859, on the occasion of a second visit to the same station. It is believed that the result reported is a pretty close determination.

2d.

Observations for the Time. 1858, August 13th.

Sidereal chronometer No. 2557, fast:

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By 12 pairs of equal altitudes of a Cygni, observed east and west (at 20h. 36m. 38.43s.)

Result adopted-Chronometer No. 2557, fast of sidereal time for this station, Aug. 13th, 1858, (at 20h. 10m.)

+48 14.85

+48 15.15

3d. The Longitude.

The above determination of the Toledo time, and the Chicago time derived from the observations made there on the nights of August 4th and 12th, combined with the following telegraphic signals, give us the longitude of Toledo, Ohio, as follows, viz :

Determination of the Difference of Longitude between Chicago and Toledo, Ohio, by electric signals for comparisons of time, August 13th, 1858.

Sidereal Chronometer No. 2557, fast, of Toledo, sidereal time, (at 20h. 49m. sidereal time,) 48m. 15s.30.

Rate per sidereal day, + 58.62; or per sidereal hour, + 08.234. Mean solar Chronometer No. 141, slow, of Chicago, mean solar time, (at 11h. 03m. mean time,) 4m. 28s.5.

Rate per mean solar day,

08.0078.

08.187; or per mean solar hour,

1st.-Chicago signals recorded at both stations.

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1st Mean. Electric signals sent from Chicago to Toledo, Ohio, 0 16 21.642

2d.-Toledo signals recorded at both stations.

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2d Mean. Electric signals sent from Toledo, Ohio, to Chicago, 1st Mean. Electric signals sent from Chicago to Toledo, Ohio, as above,

Result:-Toledo Observing Station is east, in longitude of Chicago observing Station No. 3, by a mean of the two sets of signals,

Difference of Longitude by each signal.Toledo east of the meridian of

Chicago observing station No. 3.

h. m. 8.

0 16 21.63

0 16 21.62

0 16 21.62 0 16 21.60

0 16 21.618

0 16 21.642

-- 0 16 21.63

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Longitude of Chicago observing station No. 3, west

of the meridian of Greenwich,

Longitude of the Toledo observing station, west of

the meridian of Greenwich,

Equal, in are, to

Latitude, as before,

0 16 21.63

+5 50 31.20

+5 34 09.57 83° 32′ 23.55 W. 41° 39' 02".26 N.

From true azimuths from observations on Polaris, with the theodolite, and measured distances from the observing station, we are enabled to give the following table of the latitudes and longitudes of positions in the city of Toledo, viz.—

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On the map accompanying the report of Captain Andrew Talcott, of his operations and observations in determining the boundary line between the States of Michigan and Ohio, in the year 1833 (see Doc. No. 497 of the House of Representatives, of the 23d Congress, 1st Session), he places Toledo in latitude 41° 38' 43'', and in longi. tude 83° 22′ 28′′=5h. 33m. 29.87s. west of Greenwich, as near as we can measure by the map scale. Our latitudes agree well, considering the difference of stations occupied ; but in longitude, my determination places Toledo 9′ 50′′ in arc = 39.33s. of time west of the position given to it on Captain Talcott's map, as printed on a scale of 5 miles to 1 inch, to accompany his report. This difference in longitude is equal to 8.48 statute miles.

Determination of the Difference of Longitude between Chicago and Toledo, Ohio, by electric signals for comparisons of time, August 13th, 1858.

Sidereal Chronometer No. 2557, fast, of Toledo, sidereal time, (at 20h. 49m. sidereal time,) 48m. 15s.30.

Rate per sidereal day, + 58.62; or per sidereal hour, + 0s.234. Mean solar Chronometer No. 141, slow, of Chicago, mean solar time, (at 11h. 03m. mean time,) 4m. 28s.5. Rate per mean solar day,

08.0078.

08.187; or per mean solar hour,

1st.-Chicago signals recorded at both stations.

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1st Mean. Electric signals sent from Chicago to Toledo, Ohio, 0 16 21.642

2d.-Toledo signals recorded at both stations.

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2d Mean.-Electric signals sent from Toledo, Ohio, to Chicago, 1st Mean.-Electric signals sent from Chicago to Toledo, Ohio, as above,

Result:-Toledo Observing Station is east, in longitude of Chicago observing Station No. 3, by a mean of the two sets of signals,

Difference of Longitude by each signal.Toledo east of the meridian of

Chicago observing

station No. 3.

h. m. s.

0 16 21.63

0 16 21.62 0 16 21.62 0 16 21.60

0 16 21.618

0 16 21.642

- 0 16 21.63

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