V. A It tier frotu Mr Stephen Grayy concerning 
drawing :the Mericfian Line by the Ppk Star^ 
and finding the hour by the fame. 
Canterbury y Maj 1701. 
5/V, 
I Have fent fome farther thoughts upon the Inftrument , 
J for Drawing a Meridian line, which you had an ac- 
count of in my laft, and have improved it fo far, as that 
at flie firft mentioning it may perhaps feem a Paradox 
evgjj^to Aftronomers, when they fhall hear tha t no other 
Star will be made ufe of than the Polar one to obtain 
the hour and minute of the day or night 5 but it w^ill 
foon ceafe to be fo when L ha^ defcribed tiie Inftrtt- 
Let there be taken a Telefcope of about 16 foot, or 
longer if you plea fe, in the Plane of its focus place a 
Ring of Brafs at right angles to the iaxis of the Glafs, 
the Diameter of the inward Circle equal to the double 
Tangent of the Pole- Star from the PisJe, the focal length 
of the Obje£t Glafs being made Radius, as was faid in 
the Defcription of the Meridian Inftrument 5 let the 
'Ring be divided into 24 hours, vvith their minutes num- 
ber'd frbnrHtli'e right hand towards the left, as in our 
<!6mmoh - No^urri^^ Glafs muft be equal 
'in its' diameter to the Horary Ring : but this perhaps 
will be thought too chargeable, efpecially for fuch large 
Telefcopes as I am fpeaking of, which has made me 
think of this contrivance ^ the Eye Glafs muft lye in a 
broad Index towards one end, this is to turn on a Cen- 
ter Pin, that lies in the Center of the Glafs, and confe- 
quentiy over the Center ot the Horary Ring,from which 
N n n n n it 
