552 Description of the Anglometer. [Dec. 



Place the index A at the apparent distance on the arc of the instru- 

 ment ; then place the plain bar BC on the divided edge BE, 

 or solar line.) at the sun's altitude ; and the chamfered bar DF, 

 on the lunar line GH : mark at what division the plain bar intersects 

 it, which note down, and call it the line of correction ; and when this 

 falls to the right of the lunar line, it is subtractive ; but when to the 

 left, it is additive. 



Multiply* this line of correction by the given horizontal parallax ; 

 and divide the product by 62, when the correction is subtractive ; but 

 by 53, when additive, to find the " true correction." 



To this description I will add a comparative example by the two 

 methods. 



By the usual Formula. 



p's Apparent Altitude, 32° 30' 00"" 



,,. *'s Ditto ditto,.. 43 43 00 



Glven > i Apparent distance, 45 19 37 To find the true d 1S tance. 



|_ ]) 's Horizontal Parallax, 60 09 

 3) 's Apparent Altitude,32 6 30' 

 *'s Ditto ditto, 43 43 



Sum 76 13 Half, 38 6 Co. Tang. 10,1056 



Difference, 11 13 Half, 5 36 Tangent, 8,9915 



Apparent distance, 45 19 37 Half, 22 40 Co. Tang. 10,3792 



First Correction, .. + 6 Arc, A. .. 16 40 Tangent, 9,4763 



45 19 43 Difference, s 6 00 Co. Tang. 10,9784 

 Second Correction, — 25 43 *'s Altitude, 43 43 Co. Tang. 10,0195 



44 54 00 *'s Correction, 59 P. Log. 2,2626 



Third Correction, + 15 First Cor. 6 P. Log. 3,2605 



True Distance, .. 44 54 15 Sum, 39 20 Co. Tang. 10,0865 



}) 's Altitude, 32 30 Co. Tang. 10,1958 



J'sCor 49 15 P. Log. 0,5629 



2nd Cor 25 43 P. Log. 0,8452 



Given as above. By the Anglometer. 



Line of Correction, 25' 45" P. Log. 8445 



J 's Horizontal Parallax, 60 9 P. Log. 4760 



1,3205 

 Constant Log. 4629 



8576 



Correction, 24 59 



Apparent Distance, 45 19 37 



True Distance, 44 54 38 



* The use of proportional logarithms will simplify this operation. 



