436 Astronomical and Nautical Collections. 



plement and of the angle C (observing the algebraical rule of 

 the signs as in addition) is the complement of the parallactic 

 orbital angle, or the complementary angle with its proper 

 sign. When this angle exceeds 180°, its supplement to 

 360°, with the sign reversed, is to be taken. 



Example. — At Port Bowen, on 3rd January, 1825, the 

 immersion of n Geminorum was observed at 5^' 9"' 27' appa- 

 rent time. 



Complement^ angle =+ 23 42 20 



2, Add together the log. cosecant of the horary angle, 

 the log. cosecant of the north polar distance of the zenith, 

 the log. sine of the angle C, the log. secant of the comple- 

 mentary angle, and the proportional logarithm of the moon's 

 horizontal parallax, corrected for the spheroidal figure of 

 the earth ; the sum is the proportional log. of the perpendi- 

 cular parallax, which has the sign + or — , accordingly as the 

 complementary angle is greater or less than 90°. To the prop, 

 log. of the perpendicular parallax add the log. cotangent of 

 the complementary angle, the arithmetical complement of the 

 prop. log. of the moon's horary motion, and the constant log. 

 0*4771, the sum is the prop. log. of a portion of time, which, 

 added to or subtracted from the time of observation, accord- 

 ingly as the parallactic angle (or its supplement, in the 

 case mentioned above) has the sign + or — , gives the time 

 corrected. 



