PHYSICAL AND LITERARY. 99 



Thefe two parts for the tabular latitude are 

 found thus. To the given Ion. add 6 figns ; 

 and take out the merid. parallax anfwering 

 to each longitude. Half the fum of thefe 

 gives the ift part, and half their difference 

 the 2d part, to be added to the firfl when the 

 merid. par. for the given Ion. is greater thaa 

 the other, and to be fubtrafted when, lefs. In 

 like manner, the equation for the femid. 

 confifts of two parts; the. ifl of which is pro- 

 portional to the fine, the 2d to the cofuie of 

 lat. The ift part is the equation for the given 

 Ion. 0, and 6 hours from noon ; and this 

 fubtraded from the equation for the given 

 Ion. © and hour from noon, gives the 

 2d part. 



15. The fame rules will ferve for finding 

 the moon's parallaxes from a fixt ftar or pla- 

 net. If the femid. of the planet have no 

 fenfible magnitude, there will be no place 

 for the corredion mentioned in art. 6. But, 

 as the requifites could not be found from the 

 common tables, if the ftar has latitude, it 

 will be convenient, firft, to fuppofe it has 

 none, and afterwards to apply a proper cor- 

 rection. Befides, the proceeding in this way 

 ^ill make the tables already defcribed to be 



of 



