GEOGEAPHICAL POSITIONS. 73 



1. Boston. — Dr. Bowditali, from six astronomic observations, viz., two transits and 

 four solar eclipses, made the longitude of Boston as 4'' 44™ 16-6' ; and it was the opinion 

 of Dr. Bowditch that this longitude was more accurately ascertained than that of any 

 other place in the United States. The State of Massachusetts was surveyed trigono- 

 metrically, by Simeon Borden and Robert Treat Payne, Esqrs., and the survey was 

 based on the position of Boston State House. " From observations in 1829 and 1830," 

 says Mr. Borden, " I made the longitude of the State House as 4*" 44™ 146% and by the 

 great solar eclipse, May 15th, 1836, 4*^ 44™ 19-6'; mean of the whole, 71" 4' 13-5''." The 

 latitude deduced as 42° 21' 22-7", was from 636 observations. 



2. CAMBRIDGE OBSERVATORY.— The longitude of the Observatory of Cambridge 

 near Boston, is the primary meridian of the greater portion of N.W. America, inasmuch 

 as the longitudes of most other places have been referred to it by triangulation, or by 

 electric signal. Its relation to Greenwich has also employed years of assiduous labour 

 and consummate skill, and may now be considered as entirely established, within probably 

 an insignificant amount of error. 



Prior to the year 1849, the astronomic observations systematically carried on there had 

 resulted in a longitude assumed as 71° 8' 0" West of Greenwich. "When the positions 

 of the United States Coast Survey Stations were published in 1851, it was assumed as 

 71° 7' 22-5", from the following data: — Moon culminations at various Observatories 

 referred to Cambridge, 4'^ 44" 28-4' ; by eclipses and occultations in the same manner, 

 .411 44m 29-6«; and by chronometric differences to that date 4'' 44™ 30•l^ This latter 

 determination was afterwards assumed by Professor Bond to be very nearly the true 

 longitude. 



But in 1855 the chronometric operations were again resumed early in January, and 

 the first meridional distance was carried by the steamer America, June 5th, and the last 

 by the return of the Africa to Boston, October 26th, 1855. There were six voyages 

 across the Atlantic, between Boston and Liverpool, and the total number of chronometers 

 used was fifty-two, and the final longitude determined was as follows : — 



h m a 



Voyages from Liverpool to Cambridge 4 32 31-92 



Voyages from Cambridge to Liverpool 4 32 31-75 



Mean 4 32 31-84 



Liverpool West of Greenwich 12 0-05 



Resulting longitude 4 44 31-89 or 



Cambridge 71° 7' 58-55" West of Greenwich. This longitude, which is 1-79' in excess of 

 the longitude of 1851, is a very close approximation to that established by Dr. Bowditch 

 and Mr. Borden for Boston as in the previous Note, and is also nearly identical with 

 that of New York, as obtained by Mr. Dent's chronometers in 1839. Later observations 

 make the longitude to be 71° 7' 39" W., as given in the Table. 



3. New York. — In the Ladies' and Gentleman's Diary, or United States Almanac, for 

 1820, Mr. Nash, the Editor, having the reputation of an excellent observer, gave parti- 

 culars of a great many meridian and circum-meridional observations taken at his school. 

 Broadway, New York, from which he inferred the latitude of No. 331, Broadway, as 

 40° 42' 58". The difference of latitude, trigonometrically found, between Mr. Nash's and 

 the City Hall, was somewhat less than 1,300 feet, which, assumed as 13", gives the 

 latitude of the City Hall 40° 42' 45", i.e., allowing 40° 42' 58" as the latitude of No. 331, 

 Broadway. By observations of a solar eclipse, which Dr. Bowden observed at New York, 

 he found the difference of longitude between Greenwich and Colombia College, equal to 

 740 0' 45" W. On the 29th of May, 1818, at a few minutes past noon, the longitude of 



N. A. 0. 11 



