Mr. Bowditch’s observations of the solar eclipse, Sept.1811. 257 
Barraud, carefully regulated for several days before and after the 
eclipse,3by equal altitudes of the sun, by a sextant and a surface of 
molasses. ‘To verify the regulations of the time-keepers used in our 
observations, we compared them together for several days before the 
eclipse, and ascertained their relative rate of going. They were also 
compared a few hours before the eclipse and immediately after it, and 
we found, that at the beginning and end of the eclipse, the regulation 
deduced from his observations agreed exactly with mine. The tel- 
escope used by Mr. Lambert was a Gregorian Reflector, 18 inches 
in length, and his manner of observing and counting time was simi- 
lar to that in my observations. ‘The result of his observation is, 
Beginning of the eclipse Of. 55’ 24-3 apparent time 
End of the eclipse § 69 Ob 
From these observations Mr. Lambert calculated the ecliptic con- 
junction to be at 2h. 13’ 31"6 apparent time, using the elements as 
given in the Nautical Almanac, without correcting for the errors in the 
moon’s longitude and latitude. This differs but one second from the 
result found by using Burg’s and Delambre’s Tables, corrected for 
the errors in longitude and latitude, as will be shown hereafter. 
The observations made at Salem are useful in finding the error of 
the lunar tables in longitude, and the apparent time of the conjunction 
under the meridian of Greenwich. _ To do this, it will be necessary 
to ascertain the longitude of the places of observation from Greenwich, 
to as great a degree of accuracy as possible; and as these longitudes 
ate made to depend on that of Harvard Hall in Cambridge by means 
of the above survey, it will be necessary in the first place to calculate 
the longitude of that University, from the observations made at Cam 
badge, Chelsea, Salem, and Newbury. | ) 
