234 



REPORT 1866. 



IT = the moon's equatoreal horizontal parallax, 

 E= the moon's true semidiameter in seconds. 



The following elements, already comijuted, will be found in the ' Nautical 

 Almanac,' page 491, year 1867; 489, year 1868 ; 490, year 1869 ; 493, year 



1870. 



i = inclination of the moon's equator to the earth's equator. 



A = arc of the moon's equator from its ascending node on the earth's 



equator to its ascending node on the ecliptic. 

 S '= M. of the ascending node of the moon's equator on the earth's equator. 

 1 =: moon's mean longitude. 

 Por the formulae see ante, sect. 7, p. 224. 

 In addition, — 



p = log of earth's radius at the place of observation. 

 (j)' = latitude of the place of observation corrected for the spheroid. 

 .& = sidereal time of observation converted into arc. 



E.vample. 



Taking Lohrmann's example, we have, 1823, October 22, 0" 35"" 15% time 

 time Dresden, 



Thoophilus from the N. limb 48-32 



)) ), E- J) 5561 N 



Moon's semidiameter 38-79=E', 



aU in micrometer revolutions corrected for refraction. 



Fig. 11. 



In fig. 11 let F be the measured point, then x= the coordinate in the 

 parallel, and 3/= the coordinate in the declination circle. Accordingly, 



ar=+16'-82, y = —9'-5S. 



The values of the above-named elements at the time of observation were 

 as under: — 



