LONGITUDE. 



Example IV. — By Mendoza's Method, 

 ©'s altitude 32" 3j'. d 's altitude 39 3'. Apparent diftance 86^ 10' 19'". 



Horizoutal parallax j8' 28". 



This method is not only extremely fliort and eafy, but is exempt from any poffible confufion of figns, all the cor- 

 reftions being additive. It is really fo perfeA, that it fhould fuperfede every other now in ufe. 



Mr. Mendoza's formula is 



Sin vpr n -1. ., - y ^'"- '*'^''- (-^ + H) + fi"- 'er. (J+ M) -(- fin. ver. (</ ^ M) = P 

 oin. ver. -IJ + 4 - | ^ fin, ver. (a + A + M) + fin. ver. ( (a + A) wT M) = Q 



of. A cof. H 



2 cof. M being taken = 



The operation performed by his tables is as follows ; 



Obferved altitude O - - 



Ditto ) . . 



Sum .... 

 With h in Table VI. take 

 d - take M and 



The fum 



With (a + h) and M in Table XI. 



(A + H) - - XI. 



J and M - - XI. 



cof. a cof. h 



h 

 a 



a + i 

 60' — r + p 



A + H 



= refraiS. p = parallas. 



take Number 



II = fin. ver. (180' - (A + H) - 59*) 

 III = fin. ver. {d + M) + Cm. ver. {d <t M) 



The fum or number IV = fin. ver. D + 4 = I + II + III = IV 



By the method propofed in the Appendix of 

 his death. A very good table of verfeJ fines 

 The apparent diftance of the moon's centre 

 centre 32° 34' 47'; the apparent altitude of 

 required the diftance of their centres. 



D *s horizontal parallax o^ 58' 



0's apparent altitude 32 34 



J 's apparent altitude 39 3 



Example V. 



the requifite Tables publifhed by Dr. Malkelyne a very (hort time before 

 accompanies it. 



from the fun's centre being 86" 10' 19'' ; the apparent altitude of the fun'« 

 the moon's centre 39 3' 4"; and the moon's horizontal parallax 58' 28"; 



Difference of app. altitude 

 Apparent diftance 



6 28 

 86 lo 



28" 



47 — I 22 / , , j'( ^ijoie correftion. 



4 + 44 '4 J 

 — Table IX. 



17 N. verf. 006373 Table X. 



19 N. verf. 933237 



Difference of true altitudes 7 14 



True diftance - 85 43 



926864 



Nat. No. to log. 919344 

 53 N. verf. 007989 



Logarithm 



N. verf. 925333 



9.995526 

 10 



Referved logarithm 9-9955 1 6 

 Logarithm - 5.967016 



5.962532 



Yy» 



Exai^ple 



