The fame may be done with an ordinary Sea Compafs , fo it 
fiaveaCircle cowards the Limb of the Card divided into De- 
grees , by faftening a final! Thred , Lute-ftring or Wire (not of 
Iron) fo upon it , as to pafs juft over the Center of that Circle; 
and placing a ftrait piece of Wood orBrafs-wire perpendicular on 
the edge of the Box at the end of the Thred, and. turning it to the 
Sun 5 till the Shadow of it fill juft upon the Thred :• then obferve, 
what Degree bf' the Circle on the Card the Thred cuts , by 
looking plum upon it | and that is the Suns Magnetic al Az>i< 
muth , . 
But to have the Variation to Degrees and Minutes (which is 
moft defirable) then the Observation laft mention'd muft be made 
with a Quadrant , Sextant ? or fome fuch other Inftrument, fo 
large as to admit of the diyifion of a Degree into Minutes ; which 
will require the Radius to be about three foot ; the larger the bet- 
ter. If a Quadrant, then, it being laid flat , and the Square Box; 
with the Needle placed upon it 5 move the Quadrant to and again 3 
till that fideof it, on which the Box is placed, lie parallel to the 
Needle, when at quiet : Then the Sight of the Quadrant being 
Aid along the Rimb of it , till the Sun fliine on both its Tides at 
the fame time , the Mid-Line ( that divides equally the Sight 3 , 
when the Sun ftnnesuponit thorow the flit will mark the Degree 
and Minute of the Suns Magnet ical Azimuth. All which is eafie to 
be put in.jgpj^e. 
And if many fuch Obfervations be made by feveral perfons at ; 
the fame place, and by the fame or other perfons diftant from one 
another/ 1; io. 20. or more Years ; Not only will the Compafs 1 
become more ufeful than formerly; even to be conducive poifibly 
to the finding the Longitude at Sea, at leafi in fome places: but 
1 the- variation of the variationof the Needle being known in dif- 
ferent places, all will be reduced to Rules; and fo from hence, Phi- 
1 lofophical or Natural Knowledge, will probably be enlarged by a 
happy difco very of the true caufe-of the Verticity, or Directive - 
1 faculty of the Loadftone ; one of the Noble fl and moft abjlrufe > 
fhanomena> that falls under the cognizance of humane Reafon. 
To find this variation- by theScars, is fo eafie, as every Mafier 
< can do it *, feeing there is no more requifite, than to find out the 
1 true North, that is, the Meridian, and compare the Needles pofiti- 
