VOL. LIX.] PHILOSOPHICAL TRANSACTIONS. 663 



Letters addressed from M. De la Lande,* to the Astronomer Royal; and 



from a Letter from M. Messier to Mr. Magalhaens. p. 374. 



M. Messier, with the best achromatic telescope at Paris, of 12 feet focus, 

 made by M. Antheaulme, observed the first internal contact at 7" 38" 48' 

 apparent time reduced to the Royal Observatory, and, he thinks, without an 

 uncertainty of 2 seconds: and this is the observation in which M. D. most 

 confided. M. Du Sejour, and M. Cassini, the son, at the Royal Observatory, 

 with much less telescopes, observed it also at 7^ 38™ 43'. M. De Fouchy, 

 M. Bailly, M. De Bory, and two opticians, who were at the Meute, observed the 

 contact at 7^ 38™ 45% reduced to Paris. M. Cassini de Thury, at the Royal 

 Observatory, noted it at 7^ 38™ 53'; M. the Duke de Chaulnes at 7*' 38™ 57'; 

 both with new achromatic telescopes of Dollond of 3-i- feet. M. Maraldi, at 

 the Royal Observatory, observed at 7'' 38™ SC, with a good achromatic telescope 

 of 3 feet, made at Paris, but he thinks the observation liable to an error of 10 

 seconds. M. Le Monnier, at St. Hubert, observed at 7'>38™ 5J% reduced to 

 Paris, by adding 1" 58'. M. Fouguere, at Bourdeaux, at 7^ 38™ 50'i, reduced 

 to Paris, taking in the difference of parallax, which is 2 seconds greater at Paris 

 than Bourdeaux. ,n..) m lij 



They received several observations of the eclipse of the sun. M. de Thui'tf 

 saw the beginning at 6'' 46™ 49' apparent time. M. Jeaurat, at 6'' 46™ 40% at 

 the Military School, which is 7'i to the west of the observatory. M. Maraldj 

 saw the end at 8'' 37™ 1 !'• M. Jeaurat at 8*^ 27"" 4', or 8'' 27™ 1 1% reduced 

 to the observatory. M. Messier at 8*' 27"" 24'. 



The observers at Rochefort, Lyons, and Avignon, did not see the transit of 

 Venus; it was observed at Brest at 7*" 12™ 5', or 40 seconds later than at Paris, 

 if we suppose the difference of the meridians to be well known. This point 

 shall be examined hereafter. M. D. could not observe the internal contact of 

 Venus; he was precisely in the place where the clouds came on 25 seconds too 

 soon ; neither was it observed at the Military School, which is close to Paris. 

 There was also another observer at Brest, M. Verdun, an officer of the marine, 

 who observed the internal contact of Venus at 7'' i 1™ 37' apparent time, which 

 makes 7^ 38™ 58', reduced to Paris. The end of the solar eclipse was observed 

 at Brest at 7^ 56™ 33', and 7^ 56™ 44', by the different observers. 



M. Pingre, at Cape Francois, observed the two contacts of Venus in the 

 latitude of ]Q° 47 at 2'' 26™ 12*, and 2*" 44™ 44', apparent time, with a 5 feet 

 achromatic telescope, but we do not yet know the longitude of the place 



• This celebrated astronomer, Hieronimus De Lalande, died at Paris the 7 th of April, 1807, at 

 75 years of age. By his will he ordered his body to be dissected, and his skeleton to be placed in 

 the Museum of Natural History. But his friends, regardless of the injunction, caused the body to 

 be interred; and his funeral was attended by most of the members of the National Institute. 



