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LVII. Reduction of the Observation of the Transit of Mer^ 

 airy over th^ Sun, observed at the Royal Observatory, 

 Greenwich^ on the 8th of November, 1802. Commu- 

 nicated by T. FiRMINGER, Esq, 



JL HE particulars respecting this observation are detailed in 

 the annual sheets published by the Royal Society; but as 

 these sheets contain nothing more than a mere register of 

 the astronomical observations made in the Royal Observatory 

 at Greenwich, they are in general so little interesting, as to 

 be found in the hands of-but few astronomical or mathema- 

 tical persons. It was therefore thought advisable, previous 

 to giving a reduction of this transit, to transcribe the obser- 

 vation, as given in the account of the Greenwich observa- 

 tions of that year. 



Transit of Mercury over the Sun on the 8th of November, 



1802. 



^^ I fitted the divided achromatic object-glass micrometer 

 to the 46-inch achromatic telescope, and adapted the tele- 

 tscope to distinct vision, by trying it upon a large spot near 

 the western limb of the Sun ; which 1 had no occasion to 

 alter duriog the whole period of the observation, as I con- 

 tinued to see Mercury perfectly distinct and well defined to 

 the end of the transit. After having made this arrangement, 

 I began measuring the distance of Mercury from the Sun's 

 nearest limb, by bringing the exterior limb of Mercury to 

 touch the interior limb of the Sun, and obtained the follow- 

 ing set of distances. 



Vol. 30. No. 1^20. May 1808. T Time 



