The Deſcription, Lines. J

A Line of Inches num bred with 1, 2, 3, unto 26; each Inch

e ſubdivided into ten parts, anſwerable to the Inch Line upon

the Staff..

4. A Line of ſeveral Chords, one anſwerable to a Circle of twelyeInches Semidiameter, numbred with 10, 20, 30, unto 60, another aSemidiameter of a Circle of ſix Inches; and the third to a Semidia-

meter of à Circle of three Inches, both numbred with 10, 20, 30, un-

ö 50 A continustion of the Meridian Line from 57 gr. of Latitudeunto 76 gr. and from 76 to& 4 gr. 5

For the Iaſcription of theſe Lines. The firſt for meaſure is equally

divided into Inches, and tenth parts of Inches. f

The Tangent on the Staſt for obſervation of Angles, with the Tan-gent of 20 and the Tangent of 30 on the Croſs, may all three be in-ſcribed out of the ordinary Table of Tangents.

The Staff being 36 Inches in length; the Radius for the Tangent onthe Staff will be 13 Inches and 103 parts of oO: ſo the whole Linewill be a Tangent of 70 gr. and muſt be numbred by their Comple-ments, and the double of their Complements, the Tangent of ro gr.being numbred with 80 and 160 e

The Radius for the Tangent of 20 on the Croſs, will be 3 6 Inches,and the whole Line between the Sights a Tangent of 3 6 gr. 3 m. accord-ing as it is numbred, The Radius for the Tangent of 3 0gr. on theCroſs, will be 22 inches and 695 parts of 1000: ſo the whoſe Line be ·tween the lights will contain a Tangent of 49 gr. 6 m. in ſuch ſort asthey are numbred. g 2

The Meridian Line may be inſcribed out of the Table which J ſetdown for this pur poſe in the uſe of the Sector. f

The Line of Numbers may be inſcribed out of the firſt Chiliad ofMr. Briggs Logarithms? and the reſt of the Lines of proportion outof my Canon of Artificial Sines and Tangents, and in recompencethereof this Book will ſerve as a Comment to explain the uſe of my

Canon.