( 111 ) 



D and g eonld be derived from Tables I and II at the end of 

 Newcomb's j)aper M ; lliere, liowever, in agreement with the method 

 introdnced by Hansen in ids tables of the moon, the nnit is not a 

 degree, but a mean day, so that the nnmbers derived from those 

 tables mnst be multiplied by 12°, 19 and IS^Ofio respectively in 

 order to be i-ednced to degrees, g' eonld be derived with a sufficient 

 accuracy for our purpose from the tables of Laroeteau in the Conn, 

 des Temps for 1846. 



The corrections found are, however, not to be applied to the true, but 

 to the mean longitude, called by Hansen n <f z, and therefore must be 

 reduced to corrections of the true longitude by multiplication by 

 (1 -\- 2e cos g ....),, and these must again be reduced to corrections 

 of right ascension and declination; for the latter reduction I used 

 the moon's hourly motions in R. A. and declination from the Nautical 

 Almanac, \vhence the direction of the moon's motion with regard 

 to the parallel could be directly derived. 



The corrections of the moon's ephemeris in the Nautical Almanac, 

 gi\-en by Newcomb on p. 41 of his Investigation for each day 

 from 1 Sept. 1874 to 31 January 1875, were corrected for the 

 two first months by means of the values found; and in the calcnla- 

 tion of the longitude from the occultations we have now applied 

 these corrected cori-ections, instead of the corrections furnished by 

 the meridian observations. It then would become evident which 

 corrections were to be preferred, and it soon appeared that it was 

 the former. The lai'ge corrections in declination found for 19 Sept. 

 and 16 Oct. 1874, ( — 4". 3 and — 4".l) for instaiice, in consequence 

 of which the second occultation observed on 19 Sept. was formerly 

 rejected, were apparently due to the inaccuracy of the meridian 

 obserxations. 



I now shall give the details of my calculation, (see table p. 112). 



These corrections were added to those given on p. 609 of my 

 first account as being interpolated from Newcomb, and then the 

 required alterations were made in all the calculations of the occul- 

 tations. 



Before I passed on to this second communication, I have once more 

 thoroughly revised all the computations and thus was able to apply 

 some corrections; some occultations which had been rejected, could 

 now be retained after the error had been corrected. 



1) S. Newcomb. Investigation of corrections to Hansen's Tables of the Moon ; 

 with tables for tlieir application, forming Part III of papers publislied by tlie Com- 

 mission on the Transit of Venus, Washington, Government Printing Office, 1876. 



