But thirdly, If fi's Surveyor do not allow for the Va- 
riar ion of the Needle, he will never exadly determine 
even the Points G, F, H, &c. or any other Points in 
the Plat; but inftead thereof will fall on the Points 
From what has been laid down, we may fee the ab- 
folute ni^ceflity of allowing for the Variation of the 
Magnet, in comparing old Surveys with new ones,- 
for want of which great Difputes may arife between 
neighbouring Proprietors of Lands : and it were to be 
wilh'd that our Honourable and Learned Judges would 
take this Matter into their Confideration whenever any 
Bufinefi of this kind comes before them. Hitherto an 
abfolute Acquiefcence in the Down Survey, without any 
of the fore- mention'd Allowance, has been agreed upon 
as a (landing Rule in our Courts of Judicature in Ire- 
land ; but that many Men may be injured thereby, I 
fuppofe is manifeft from what foregoes* 
I have only this to add , That leaft I be thought 
herein to ftrike at the Truth or Exadnefs of the Down 
Survey, 'tis not at all the intention of this Paper , but 
rather to confirm it, by (hewing which way Men ought 
to Examine it truly , and not by the common ways uTed : 
by them, which rathe:r confound it , and all that claim i 
under it. 
Seethe Talk Fig. 6. 
Although this Paper was chiefly defigned for the end-^ 
ing of Contefts in the Kingdom oi Ireland about the in- 
terefts of feme of thofe whofe Lands are Neighbouring, 
and have been Surveyed by Magnetick Inftruments, yet 
confidering its univerfal Ufe, it was thought it would 
bs very grateful to the Curious to publifli it here. 
Y:EMraSj 
