i93

GEODÆSIA Improved.

End, that is, between 3 and 4; the 3 represents 30 Links, andthe 4, 40 Links; so that you must compute, as near as you can, the8 odd Links between the said third and 4th Division ; and from8 to that Place, is the Extent 81.38 required.

There are other Scales equally divided to measure and plot by,as the diagonal Scales, Gunter' s Scale, &c which are partly thesame with the common plain Scale, in regard to a Scale of equalParts.

The common plain Scale is made 6, 9 or 12 Inches long, butGunter't Scale is two Feet: The plain Scale has the Diagonal,the Line of Chords, Rumbs, Sines, Tangents, and Semi-tangents,Sic. on one Side (which are all Scales unequally divided ) Gun-tcr' s Scale hath all the above-mentioned Lines or Scales on oneSide, that the plain Scale has upon both ; and on the other Sideof it, there are Lines of Proportion, namely, Lines of Numbers,Sines, Tangents, Sic.

First of the Line of Chords.

The l ine of Chords (marked Cho.) is a Line os unequal Parts,numbered 10, 20, 3®, &c. to 90, the Divisions thereof erowless as the Numbers increase Thcie is commonly a Brass Pointat the Beginning, and also one at 60; the Chord of 60 beingequal to the Radius, or Semi diameter of a Circle, that Extentcalled the Chord of 60, is always taken to make or measure An-gles with, and is applied to no other Purpose.— How this Line ismade use of shall be (hewed in a proper Place,

Of the Line of Numbers ►

The Line of Numbers is also one of those Lines upon Gun-trr’s Scale, commonly called Gunter s Line \ and upon the Scaleis distinguished by the Name of Line of Numbers , marked Num.or Numb: It is numbered from the Left hand, with 1, 2, 3,Sic., to 10 to the middle ef the Scale; and fiom thence to theRight-hand, with 2, 3, 4, Sic. to 10 again ; the Divisions areunequal, decreasing from the Left to the Right, as the Numbers

B b 2 increase ;