[ 42 ] 
It were to be wifh’d therefore, that fuch Perfons 
as are provided with proper Inftruments, would at- 
tempt to determine, with great Care, the prefene 
relative Pofitions of feveral of the Principal Stars, in 
various Parts of the Heavens j efpecially of thofe, that 
are lead affected by Refraction: that Caufe having 
many times fo uncertain an Influence on the Places 
of Objects, that are very remote from the Zenith? 
that wherever It is concerned, the Conclufions, de- 
duced from Obfervations that are much affected by 
it, will always remain doubtful, and too precarious, 
in many Cafes, to be relied upon. 
The Advantages, arifing from different Perfons 
attempting to fettle the fame Points of Aflronomy 
near the fame time, are fo much the greater? as a Con- 
currence in the Refult, would remove all Sufpicion 
of Incorrectnefs in the Inftruments made ufe of. For 
which Reafon, I efteem the curious Apparatus at 
Shir burn Caftle , and the Obfervations there taken, 
as a moft valuable Criterion , whereby I may judge 
of the Accuracy of thofe, that are made at the Royal 
ObfervatGry : and as a Lover of Science I cannot but 
wifh, that our Nation abounded with more frequent 
Examples, of Perfons of like Rank and Ability with 
your Lordfhip, equally deftrous of promoting This , 
as well as every other Branch of Natural Know- 
ledge, that tends to the Honour and Benefit of our 
Country. 
But were the Patrons of Arts and Sciences ever fo 
numerous, the Subject of my prefent Letter is of 
fuch a Nature, as muft direct me, to beg Leave to 
addrefs it to the Earl of Macclesfield > not only as 
a moft competent judge of it j but as the foie Per- 
i 
