( 1179) 
Sir C^. ^Fre^^'s contrivance I am informed is thus, At 
one end of a Ruler,- ereft a Sight, to fee the Pole-Star, 
d^c. through. At the other* end fet up two Circles of 
fmall Wire, on& within the other 5 the - Diameter of the 
innermoft, equal to the doubled Tangent of thediftance 
of the Pole-ftar from the Pole, the diftance of the Sight 
being Radius 5 and the Diameter ®f the outermoft Circle^ ' 
equal to the double Tangent of the diftance of the next 
Star to the Pdle-Star, from the Pole. Tom Inftrumeot 
thus prepared, if you look thro the Sight, and bring. the 
twoCircles to the two Stafs,whofe diftancesfrom the Pole 
they reprefent, a Linepaffing through a Sight and CeO'- 
ter of the Circles, is the Elevation of the Pole : and 
two Plumb^ines hung up, one over the Sight, the other 
over the Center of the 2« Circles^ will exaftly lye in the 
Meridian of the Place* 
Mr Gra/s Ingenious Contrivances being in the Philof, 
Tranf. Nrs 268 and 270, I (hall not need to give any 
defcriptionof them, but refer to his own much better 
account. . 
The laft loftrument is v/hat I have made ufe of for 
feveral years faod was it not a yiolation of the Rules of 
Modefty to fpeak well of my own) I would reco|iimend 
it, upon my own experience, for a very nice way to lied 
the Meridian of any place, and to fee the Tranf ts of the 
Celeftial Bodies over it,either Northward or South v/ard. 
The Inftrument is thus made of Wood,~'or ra ther ffcn> 
or Brafs, to indure the '¥/eather, without fwellicg or 
contrafting, viz. Prepare a fQ,iaiiflat iron Bar, as in F/(?:. 
^••i. C. C. At each end of which Rivet on two upright 
Sights^ to turn ftiffly, at the Joynts i "L Let one of 
the Sights c, d. have a perforation bni t f crr -h to' f e the 
Vok'Star through it ^ the other Sip--- a very fmdl 
perforation, to fee the 5"^» through.. bthind the 
Joynts fix two upright ArmsC D. Sc C but to bend 
ofFj fo as to be -out of the way of the Sights^- when to-u 
O 00000000 2 look 
