LONGITUDE. 



Example I. Mackay's Method, which is the fame as the preceding. 



the apparent diftance between the centres of the fun and moon be 86" lo' 19" ; the apparent altitude of the fua 

 ' 47" ; the apparent altitude of the moon 39" 3' 4" ; and the moon's horizontal parallax 58' 28". 



Let 



32' 34' 47 



Apparent diftance 



Difference of apparent altitude 



86° 10' 19" N.V.S. 933237 

 6 28 17 N.V.S. 006373 



Log. diff. Tab. XLII. 9.995517 



Correfted D 's altitude 

 Correfted G 's altitude 



Difference of true altitude 

 True dillance 



+ 44 14 Diff. 926864 



+ I 22 N. No. 917333 



Log. 



5.967010 

 .962527 



7 14 53 N.V.S. 007989 

 85 43 2 N.V.S. 925322 



This is a (hort and very excellent method, in cafe the mariner (hould not poflefs Mendoza's tables. 



Example by Mr. Turner's Method. 



Table XV. of Nautical Almanac. 



Horizontal parallax 



Moon's altitude 



Sun'6 altitude 



Apparent diftance 



Firft correftion from the Tables 



Firft correfted diftance 

 Second correftion 



Second correfted diftance 



This method was publilhed in a very fmall volume by the author at Portfmouth. 



Apparent diftance 86^ xo' .," Hor. par. 58' 28'' } ^.X^P-^nt^aSde 



By Garrard's Tablets. 



tt' c 1 ''Ti\ -^°'- P^^- °'58' 28" D 's app. altitude 39^ 3' 4"+ 44' 14"! ' '' _ p , 



H. Suppl. 9.9546J *^ ©'s app. altitude 32 34 47 - 1 21 | ^^ ^5 iTo. log. 0.59&4 



No. I. 



32" 34' 47"- 

 39 3 4 



No. II. 



No, 



1 39 22 



9.2076 



This method, by a fmall fet of tablets, has lately been publiftied by Mr. W. Garrard, of the Naval Afylum, Greenwich. 



There is a formula in Keith's Trigonometry, which might be fimplified and reduced to the following method. 

 Apparent diftance 86- 10' 19'' - Nat. cof. 066762 



Difference of apparent altitudes - Nat. cof. 993629 



Difference 926867 



Log. 5.9670174 



Log. diff., or referved logarithm. Table IX. reg. tab. orl 

 Table XLII. of Mackay - . - - J 



Nat. num. 917349 

 Difference of true altitudes - - Nat. cof. 992043 



Log. 

 Sum 



9.9955169 

 5.9625343 



True diftance 815° 43' 59" 

 10 



Nat. cof. 074694 



In 



I 



