

ASTRONOMICAL PAPERS 



169 



Then F G will be the parallax of longitude, and G H of 

 'atkude. Make o n~half the parallax of latitude found a- 

 bove. Draw q n K parallel to D L o. Joui SK which 

 fhall be perpendicular to H L. Thenthe triangles FHG, 

 K S n are fimilar; and Kn:nS::HG:GL. Thus 

 GL may be found. Let us, for an example, takeNorriton, 

 HG the parallax of latitude (under the denomination 

 of LN) was already found =4^^8245; whence 



22 



HG 



n 



2 '',4 1 



Coy^^j'SyB—n S. Moreover 



a/: 



975 



o n. And oS — on:::inS; that is 610'' — 2"54i22 



! n Si Kn ; That is 



6o7,5878=^762''536=:Kn. Wherefore finceKn: 

 n S : : HG ; GL; we have 762^536 : 607^,5878 : : 4^8245 : 

 3^8432r.GL. 



Thus the parallax of latitude HG~4''58245 

 accelerates the contad only by GL 



To which add the parallax of longitude EG^ 

 found above for Norriton 



fcconds. 



<» 



3,54^ > 



O 



10,592 



H>4352 



And we havethe whole fpaceFL by which 

 the cohtad is haftened at Norriton, by the 

 parallaxes both of longitude and latitude _^ 



Now as the motion of $ in an hour is 239'^589i; flie 

 will require 2 i6^',624of time, to pafs over the above paral- 

 laftic fpace of I4'',4352. And by fo much will the ex- 

 ternal contact be accelerated at Norriton in time; viz. 

 216^624. 



By the like procefs for Greenwich, (ufing fig. 8, where 

 ' ' "^ 7 before), we fliall find the whole paralladic 



g 



wc had fi 

 fpace, DL 



which gives in time=405 



2 7%044i 





for the acceleration of ext. 

 contad: at Greenwich, 

 But, 2 1 6,624 was the acceleration at Norriton. 



The difference 1 89^,222, is the abfolute time, by which 

 the external conta6l Ihould have been feenfooner at Green- 

 wich than at Norriton, if the Sun's horizontal parallax were 

 truly a{rumedzi:8'\52i2 on the tranfitday. 



But at Norriton thecxt.contad was obfcrved, at 2\i2'»5o'' 



^ Add 



