78 



extended than it is in the latter editions of the requisite^ 

 tables. But from the vahie of N, which has been here given, 

 this table may be reduced to tables of the same conciseness 

 and convenience as those that are above given for N — 1. 

 Tiius the common logarithm of the value of N above given 



sill 1" (p' sin H'+p sin H 1 sin* l'" C (//' cos H'— r'j^ 1 



~ m i— IlVe+i'tan H'+Jtan Hi 2 m { H-r^— ;/» sinMl' i 



where ?w = 2,03025 



This quantity admits of being put into tables of the same 

 form as those above-mentioned. 



Mr. Mendoza's 10th table also may be put into tables of 

 a similar convenient form, supposing his 9th table, instead 

 of containing the correction of the moon's altitude, to con* 

 tain only the parallax in altitude, and to be arranged in the 

 manner above-mentioned. 



For let M be the angle taken out in that table 

 then cos (60°+M) = J N 



Whence is deduced 



•ji*- 1 (p' sill U'-j-p sin H ") sin 1" f I fp' cos H'— ))» l 



sin 600 i_114.", (i-fJ'tan H'+Jtan H3 + sin 00° { +i r*— | {p"- sin» H') j 



7- The practical rule from the formula given in the last 

 article but one, may be briefly stated as follows : 



Practical Rule. 

 1. Find, by help of a table, the parallax answerino- to the 

 moon's altitude, and to the complement of the altitude. 

 The latter will be the argument of tab. 1. Or 



Compute them by adding the proportional log. of the hori- 

 zontal parallax to the arithmetical comp. of the log. cos. and 



log. 



