( 846 ) 
The manner of Obfervation I conceive, may be thus : 
Having firft pitched upon the Star we mean to obferve , 
and having then confidered (which is not hard to do) 
where fuch Star is to be feen in its greateft Eaft or Weft 
Azimuth ; it may be then convenient to fix (very firm 
and fteadily on feme Tower, Steeple, or other high 
Edifice (in a convenient fituation) a good Telefcopick 
Objed>glafs in fuch pofition, as may be proper for view- 
ing that Star. And at a due diftance from it near the 
Ground, build on purpofe (if already there be not any) 
(ome little Stone Wall, or like place, on which to fix the 
Eye-glaft, fba§ toanfwer that Objeit-glaft : And having 
fb adjufted it, as through both to fee that Star in its defi- 
red Station, (which may beft be done while the Star is 
to be feen by Night in fuch fituation, near the time of 
one of the Solftices), let it be there fixed fo firmly, as 
not to bedifturbed, (and the place lb fecured,as that none 
come to diforder it), and care be taken Co to defend both 
the Glafles, as not to be' endangered by Wind and Wea- 
ther. In which contrivance I am beholden to Mr. /John- 
Cafwel M. A. of Hart-hall in Oxford^ for his Advice and 
Affiftance ; with whom I have many Years fince, com* 
municated the whole matter. 
This Glafs being once fixed (and a Micrometer fitted 
to it , fb as to have its Threds perpendicular to the Ho- 
rizon, to avoid any inconvenience which might ariie 
from diverfity of Refradtion if any be) the Star may 
then be viewed from time to time (for the following 
Year or longer) to fee if any change, of Azimuth can h 
be obferved. 
This I thought fit to recommend to your Confedera- 
tion, whodo ib well underftand Telefcopes, and the ma- 
nagery of them; not knowing any who is more likely to 
reduce it to Practice. If you fcall think fit to give your 
felf the trouble of attempting the Experiment, and that 
it liieceed well, it will be a noble -Obfervation, and worth 
the:..- 
