it rnuft be equal to the diftance of the focus of the Eye 
Glafi), then Jet the Tube be elevated to the height of the 
Pole, and direfted to the Pole Star, till by turning the 
Index through the . Eye Glafs, ypu perceive the Star to 
touch the iHprary Ring on tha^ fid.e. the Star in the Great 
Bears Pvump 1 yes, or' oq ' the b^po^ite to that in the Hip 
of CaJ/iopeia 5 but the contrary, "had not the Gfefe inverted 
the Object, then bring one of the 12s to be in a perpen- 
dicular to the other by a Plum line, fo will the Star 
ftand at its Horary diftance trom the Meiidian 5 or if the 
Latitude of the Place be unknown by the- Right Afcenti* 
on of the Sun and Star, the line of itscoming to the Me* 
ridian will be eafily obtained, and then the Hour of the 
night found, will as eafily give the Stars horary diftance 
from the Meridian 5 then elevate the Tube towards the 
Star, bringing the Meridian, or 12 and 12 into thepain 
of the perpendicular, turn the Glafs about till you fee the 
Pole Star ftand at itSt Horary diftance from the Meridian 5 
fo will the Inftrument when fixed, (hew the Horary di- 
ftance throughout the whole day, or as long as it remains 
in this pofition,by the apparent motion of the Star in the 
Ring. The beft time to fix the Inftrument, will be when 
this, orany of the other two Stars above-mentioned, are 
about 6 hours from the Meridian. You raay be pleafedj 
Sir, to take notice, that the Latitude of the place is now 
given with theutmoft Precifenefs^for the axis of the Glafs 
lies now in the axis of the World, and if one of the fides 
of the Tube be parallel thereto, as it ought to be at the 
upperend, hang aLine and Plumet from the point of the 
fufpenfion 5 find another point equal in diftance to the 
length of the Line, or a knot tov/ards the lower end, the 
diftance from this knot to the former point will be but the 
Chord of the latitude, and if from the fame edge of the 
Index, another Line and Plumet be hung towards the 
lower end of the Tube, thefe two linea, when at reft, 
will be in the plain of the Meridian • 
This. 
